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('■
«
I
i •
JOURNAL
OF
BACTERIOLOGY
VOLUIVIE VI
BALTIMORE, MD.
1921
^»
CONTENTS
No. 1, Janxtary, 1921
Chemical Criteria of Anaerobiosis with Special Reference to Methylene
Blue. Ivan C. Hall 1
Powdered Litmus Milk. A Product of Constant Quality and Color which
Can be Made in Any Laboratory. Herbert W. Hamilton 43
Bacteria Concerned in the Ripening of Com Silage. P. G. Heineman and
Charles R. Hixson 46
Some Atypical Colon-Aerogenes Forms Isolated from Natural Waters.
Margaret C. Perry and W. F. Monfort 53
Botulism in Cattle. Robert Graham and Herman R. Schwarze 60
Note on the Indol Test in Tryptophane Solution. Chr. Barthel 86
The Nature of Hemolysins. J. T. Connell and L. E. Holly 80
The Nature of Toxin. The Antigens of Corynebacterium diphtheriae and
Bacillus megatherium and their Relation to Toxin. C. C. Warden,
J. T. Connell and L. E. Holly 103
The Gas Production of Streptococcus Kefir. James M. Sherman 127
The Importance of Preserving the Original Types of Newly Described Spe-
cies of Bacteria. C.-E. A. Winslow 133
No. 2, Mabch, 1021
Progress Report for 1020 Committee on Bacteriological Technic . H.J. Conn,
Chairman, K. N. Atkins, I. J.'Kligler, J. F. Norton, and G. E. Harmon. 135
A Study of the Variations in Hydrogen-Ion Concentration of Broth Media.
Laurence F. Foster and Samuel B. Randall 143 A-
The Relation of Hydrogen-Ion Concentration to the Growth, Viability and
Fermentative Activity of Streptococcus hemolyticus. Laurence F.
Foster 161 ^f
The Biochemistry of Streptococcus hemolyticus. Laurence F. Foster 211 \^
Notes on the Flagellation of the Nodule Bacteria of Leguminosae. Ivan V.
Shunk 230
Method for the Intravenous Injection of Guinea-Pigs . George B. Roth. . . 240
Rose Bengal as a General Bacterial Stain. H. J. Conn 253
No. 3, May, 1021
William Thompson Sedgwick, 1855-1021 255
The Main Lines of the Natural Bacterial System. S. Orla-Jensen 263
Variations in Typhoid Bacilli. Kan-Ichiro Morishima 275
Solid Culture Media with a Wide Range of Hydrogen or Hydroxy 1 Ion Con-
centration. Frederick A. Wolf and I. V. Shunk 325.
Studies on Asotobacter Chroococcum Beij. Augusto Bonazzi 331
111
IV CONTENTS
No. 4, July, 1021
SpiM Bodies in Bacterial Cultures. Laura Floraiee 371
The Cause of Eyes and Characteristic Flavor in Emmental or Swiss Cheese.
James M. Sherman 379
A New Modification and Application of the Gram Stain. G. J. Hucker 396
Color Standards for the Colorimetric Measurement of H-Ion Concentration. ^>
Louis J. Gillespie 399 \^
The Effect of Pepton upon the Production of Tetanus Toxin. Harriet
Leslie Wilcox 407
On the Growth and the Proteolytic Ensymes of Certain Anaerobes. K. G.
Demby and J. Blanc 419
No. 5, Septbmbbr, 1921
The Mannitol-Producing Organisms in Silage. G. P. Plaisanoe and B. W.
Hammer 431
Principles Concerning the Isolation of Anaerobes. Studies in Pathogenic
Anaerobes II. Hilda Hempl Heller 445
Indol Production by Bacteria. John F. Norton and Mary V. Sawyer 471
On Nitrification. IV. The Carbon and Nitrogen Relations of the Nitrite
Ferment. Augusto Bonassi 479
Toxins of Bact. Dysenteriae, Group III. Th. Th]0tta 501
No. 6, NoVElfBBB, 1921
Salt Effects in Bacterial Growth. I. Preliminary Paper. George E. Holm
and James M. Sherman 511
Suggestions concerning a Rational Basis for the Classification of the Anaero-
bic Bacteria Studies in Pathogenic Anaerobes IV. HUda Hempl
HeUer 621
Hydrogen Ions, Titration and the Buffer Index of Bacteriological Media. ^
J. Howard Brown 555 0\
On Decreasing the Exposure Necessary for the Gelatin Determination.
J. E. Rush and G. A. Palmer 571
Chart of the Families and Genera of the Bacteria. Harold Macy 675
CHEMICAL CRITERIA OF ANAEROBIOSIS WITH
SPECIAL REFERENCE TO METHYLENE
BLUE»
IVAN C. HALL
Prom the DeparlTnent of Hygiene and Bacteriology, Unirenity of Chicago
Received for publication June 4, 1920
The literature of anaerobic technology contains frequent
references to various criteria of anaerobiosis aside from growth
of organisms. To be sure, the successful cultivation of a known
anaerobic micro-organism under given conditions, in contrast
with the failure of growth of the same organism on the surface
of solid media of similar composition in free contact with air,
constitutes a satisfactory biological criterion of anaerobiosis for
the particular organism used in the test and under the special
conditions thereof. But there are circmnstances in which it is
desu-able to correlate other means of determining oxygen tension
reduction. An obviously useful phyncal means is the vacuxma
manometer, but most helpful of all are chemical criteria, which
are usually based upon coloration changes.
One of the earliest indicators used, and a notable exception
to the rule of indicators with coloration changes, was phosphorus,
whose failiu'e to ignite was employed by Gratama, a student of
Gunning's (1877).
A mixture of alkali with pyrogallic acid, as used in reducing
oxygen tension for the cultivation of anaerobic organisms, is
also frequently mentioned as affording a criterion of successful
anaerobiosis since in the absence of oxygen the solution remains
nearly or quite colorless. But it is scarcely possible for this
^ This essay is* based upon an investigation completed during the writer's
tenure of the Logan Fellowship at the University 6f Chicago and is one of a
series awarded the Howard Taylor Ricketts Memorial Prize for 1920.
1
JOTTBITAZ. or BAGTSBIOLOaT, TOL. TI, MO. 1
2 IVAN C. HALL
reagent to serve both as a means of removing oxygen and as a
criterion of removal at the same time, so that the latter purpose
can be achieved only when combined with other means of oxygen
tension reduction.
Fermi and Bassu (1904), using alkaline pyrogallol as a criterion,
encountered extreme diflSiculty in demonstrating complete anaero-
biosis. For example, they found that boiling media under
parafiine oil for over one hour does not prevent the darkening
of an alkali-pyrogallol mixture placed therein and a similar
statement was made respecting the passage of hydrogen and
carbon dioxide through media. It appears from my own experi-
ments that the colored compounds formed by the action of
oxygen upon alkaU-pyrogallol mixtures are quite stable and the
reactions irreversible, for neither very weakly alkaUnensolutions
which show only a trace of color with pyrogallic acid nor strongly
alkaline deep colored solutions can be decolorized by prolonged
boiling. Therefore the diflRculty of making the mixture without
obtaining some coloration and the further impossibility of remov-
ing it previous to actual test distinctly limit the practicability
of alkaline pyrogallol as a criterion of anaerobiosis, notwith-
standing its great value as a means of oxygen tension reduction.
More extensive use has been made of substances which in the
absence of free oxygen are reduced to leucobases. Some of these
can be used, not only in media during the active growth of
organisms, but separately as well, for estimating the suitability
of special apparatus. Among such indicators may be mentioned
potassium ferro-ferro cyanid, litmus, indigo (sodium indigo
sulphonate) and methylene blue.
Potassium ferro-ferro cyanid [(KaFe (Fe Cye))] is of slight
historical, but no practical, importance. It was used by Gunning
(1877) (1878) (1879) and is said to become colorless [Fe^Fe Cy«]
when air is eliminated. t
The earliest authentic reference to the bacteriological use of
litmus appears to be that of Wiirtz (1892) who introduced litmus
lactose agar as a differential medium for Bact. eoli and Bad.
typhomm. It was impossible to confirm Novy's (1893) allusion
[copied by Hunziker (1902)] to Buchner (1885) and Cohen (?)
CHEMICAL CRITERIA OF ANAEROBIOSIB 3
as first to use litmus to indicate acid and reduction changes
respectively, the last reference apparently being altogether
erroneous. The decolorization of indigo and methylene blue
in culture media were studied by Spina (1887) whose interest in
these dyes hinged rather upon their reduction by bacterial growth
though he recognized the phenomenon as occiu*ring most vigor-
ously in the depths and noted the return of color on exposure
to the air. Kitasato and Weyl (1890) confirmed this observation
so far as regards sodium indigo sulphate. The decolorization of
all three dyes by sterile culture media under anaerobic conditions,
as well as by living aerobic and anaerobic cultiu-es, was especially
investigated by Smith (1893) (1896) who noted the necessity of
some organic substance such as glucose or peptone and an
alkaline reaction in the case of sterile media decolorized by heat.
I found neutral litmus solutions unaffected in color by heating
for twenty minutes in a boiling water bath, and the same is
true of litmus with 1 per cent glucose. Litmus solutions with
1 per cent glucose and HCl stronger than n/8 were precipitated
by heating and the precipitate was not redissolved on cooling;
weaker acid solutions were unaffected except for reddening.
Strong alkali n/2 to n/32 caramelized the sugar and decolorized
the dye permanently; weaker solutions decolorized on boiling
for a few minutes and regained their original blue color only on
exposure to air.
The recoloration of such decolorized solution of Utmus, indigo
and methylene blue by exposure to air indicates reversible
reactions and constitutes the key to the use of such dyes as
criteria of anaerobiosis.
McLeod (1913) cleverly utilized the blue laboratory pencil
mark as a criterion of anaerobiosis upon the basis of its decolori-
zation in the absence of air. Some pencils fail to respond, how-
ever, according to my experience.
METHYLENE BLUE AS A CRITERION OF ANAEROBIOSIS
The most valuable and most extensively advocated chemical
criterion of anaerobiosis is methylene blue. Introduced as an
ingredient of cultiu-e media by Spina (1887), studied as an indi-
4 IVAN C. HALL
cator of anaerobiosis by Smith (1893) and others, it has been used
to a certain extent by almost every serious investigator of anaero-
bio^ since. Smith (1893) (1896) noted its decolorization in the
closed arm of the fermentation tube. Sanfelice (1893) and
liefmann (1908) defended the use of glass slips on the basis of
the decolorization of methylene blue in the underlying agar.
Trenkmann (1898) and Rivas (1902) used it in their culture tests
with Na2S as a reducing agent. Kabrhel (1899) used it in his
bell jar device for plates and thereby showed the necessity of
removing the covers for efficacious absorption of oxygen by
alkaline pyrogallol; he abo showed its value as an indicator of
the anaerobiosis of deep culture media, liquid and solid. It
was used by Petri (1900) in connection with oxygen tension
reduction by hydrogen and alkaline pjrrogallol, by Sellards (1904)
with phosphorus, by Fremlin (1903) (1904), Staler (1904),
Bemer (1904), Lentz (1910) with various plating devices, by
Wrzosek (1907) (1909), Liefmann (1907), Hata (1908), Guil-
lemot and Szczawinska (1908), Zinsser, Hopkins and Gilbert
(1915) with plant and animal tissues, by Laidlaw (1915), and
Mcintosh and Fildes (1916) in the use of spongy platinimi and
palladiimi black as hydrogen-oxygen catalysers, by Wilson (1917)
in the use of coal gas, by Douglas, Fleming, and Colebrook (1917)
in connection with many porous substances and by a great many
others.
CHEMISTRY OF METHYLENE BLUE
Discovered by Caro in 1876 and used empirically for many
years in the arts, methylene blue, as a chemical compound, was
studied most authoritatively by Bernthsen. He showed (1883)
that NazSsO^ reduces it to its colorless leuco base, methylene
white, which may be crystallized out of ether and whose aqueous
solution becomes dark blue again in acid solution with iron
chloride. Mohlau (1883) expressed the rule that methylene
white is changed to methylene blue by oxidizing agents in acid
solution, Bernthsen (1883) engaged in a brief polemic with
Mohlau (1883) and Erlenmeyer (1883) as to the structural
formulae of these compounds and finally (1884) set down meth-
ylene blue chloride as
CHEMICAL CRITERIA OF ANAEROBIOSIS
<
C,H,-N(CH,),
: >
CeHa— N(CH8)2C1
I
which is reduced (Bemthsen 1885) by the action of zinc or zinc
chloride with HCl or H2SO4 and in alkaline solution with am-
monium sulfate to leuco-methylene blue
C.H3-N(CH,)2
CJIa— N(CH,),
These formulae are generally accepted now, practically the only
disagreement being as to the direct bond between two of the
nitrogen atoms.
Landauer and Weil (1910) also obtained leuco-methylene blue
by treating a solution of the blue salt in alcohol, with phenyl-
hydrazine, warming and cooling under COs. It has a melting
point of 185°C. and is not oxidized even by pure oxygen in an
atmosphere free from acid and in strongly alkaline solutions is
not acted upon by permanganate or hydrogen peroxide. The
following equation represents the reaction
CeHs— N(CH8)2
n/ Ns + NH2NHC6H6=
CeH,— N(CH3)2C1
(blue)
CflHs— N(CH3)2
Hn/ \s . + CeHe + N2 + HCl
CcHs— N(CH8)2
(colorless)
Excepting Landauer and Weil (1910) chemists have studied
methylene blue largely from the standpoint of action of inorganic
compounds upon it. We turn now to a consideration of its
behavior in the presence of those factors which enter into bacteri-
ological culture media, since the custom, not altogether defensible,
6 IVAN C. HALL
as I shall show, has grown up of adding a trace of this dye to
the culture medium — either with or without inoculation — as a
criterion of anaerobiosis.
We have already referred to the fimdamental observations
of Smith (1893) (1896) on the decolorization of methylene blue
in alkaline solutions containing glucose or peptone imder anaerobic
conditions induced by heating. Kabrhel (1899) and Hammerl
(1901) used such a solution along with their cultures as an
indication x)f the successful exclusion of oxygen and the latter
showed that the. sugar might be replaced with sodiimi formate.
Fremlin (1904) foimd an alkalinized methyl alcohol solution of
methylene blue more delicate than an aqueous solution but
recognized the possible inhibitory action of the volatile spirit
upon bacterial growth.
As Bemthsen has shown, commercial methylene blue is likely
to be a mixture with methylene aziure, the latter being formed ]fy
the action of alkalis. Underbill and Closson (1905) have given
methods for the purification of both, which however is not
necessary in using methylene blue as a criterion of anaerobiosis
since both compoimds }deld colorless leuco-bases imder similar
conditions; furthermore methylene azure is formed from meth-
ylene blue under conditions of alkalinity such as obtain in the
test.
EXPERIMENTAL WORK
DecolarizcUion — Preliminary disciission
The writer's interest in methylene blue as a criterion of anaero-
biosis dates from the invention of the constricted tube and marble
device (Hall, 1915). It was possible to show by its use that
certain shipments of tubes contained 4 per cent with defective
bore so that they could not be used. A propferly made tube con-
taining a methylene blue solution of certain composition, with
a good marble seal will not permit the return of color below the
marble for several days after decolorization by heating. One
must not fall into the error of assuming, however, that decolori-
zation of methylene blue necessarily indicates suitability for
anaerobic growth; there are many factors, aside from the reduc-
CHEMICAL CRITERIA OF ANAEROBI08I8 7
tion of oxygen tension, in the cultivation of anaerobes. How-
ever, the failure of a properly balanced solution to remain decolor-
ized indicates a defect in the method of air exclusion proposed.
Decolorization of methylene blue probably occurs at a definite
point during the abstraction of oxygen — a point yet to be deter-
mined. So decolorization may indicate suitability for some
organisms and not for others. Methylene blue tests with
McLeod's (1913) plate were satisfactory yet the bacteriological
use of this plate in our hands was never satisfactory. Therefore,
while we must admit that the decolorization of methylene blue
solution, delicately adjusted, frequently correlates with successful
anaerobic cultures, it is more important to recognize the limits
and conditions of this test and to appreciate that the factors
which enter into the successful decolorization of methylene blue
are not necessarily common to the growth of all obligative
anaerobes. It should be emphasized especially that acidifica-
tion, probably through absorption of carbon dioxide from the
air, may account for a return of color to decolorized methylene
blue solutions and that in this case the dye cannot be bleached
again without re-alkalinization.
Essential factors in decolorization
Preliminary experiments had to do with tests of Griibler's
methylene blau ftir Bacillen in two culture media commonly
used for the cultivation of anaerobes — ^magnesium carbonate
glucose broth (Hall, 1915) and neutral (phenolphthalein) glucose
agar. A trace of methylene blue in either of these media is
easily decolorized by heating in a boiling water bath. In the
open air such decolorized solutions quickly recover their original
blue color but protected from air remain decolorized indefinitely.
Thus in the constricted tube filled with glucose broth the color
retiuns above but not below the marble seal; in deep glucose
agar the color returns to the upper layers first and gradually
descends. But it was noticed in certain cases of methylene blue
glucose broth allowed to stand for several days that heating
failed to decolorize the dye although it had done so originally.
The outcome was a series of experiments to determine the
8 IVAN C. HALL
principal factors of decolorization and return of color in methylene
blue solution.
Considering each of the ingredients of magnesium carbonate
glucose broth as possible single factors in the decolorization of
the dye, it was first shown that only those solutions slightly
alkalinized, as by means of magnesimn carbonate or sodium or
potassium hydroxide, lose color on boiling. The use of magne-
sium carbonate referred to involves addition of an excess and the
removal of the undissolved residue by filtration after boiling:
only a trace of magnesimn goes into solution and the reaction is
made faintly alkaline (pH .== about 8). With such adjustment
it was found possible to dispense with the salt and any two of
the other three factors (meat infusion, peptone, and glucose)
without interfering with decolorization. But the clearest cut
results were obtained with glucose present. Furthermore, rather
prolonged boiling is required for decolorization if the glucose be
added to the filtrate from a heated MgCOs suspension in water,
i.e., is not heated in the presence of an excess of MgCOs; a
slightly alkahne solution of 2 per cent agar was also decolorized
easily. Further experiments were then undertaken to determine
the effect of variation in reaction upon methylene blue solutions
in the presence of these various organic substances.
The following facts stand out as a result of many experiments.
Neutral aqueous solutions of Griibler's Methylene blau ftir
Bacillen containiag 0.0001 gram or more per cubic centimeter
are not decolorized in a water bath boiling hard for twenty
minutes. Neither the inorganic acids, HCl, H2SO4, HNOs, nor
the organic acids, oxalic, acetic, lactic, citric, butyric, succinic,
formic, and propionic, in a concentration of n/10, have any
visible effect when heated in weak solutions of methylene blue.
Yet methylene blue is decolorized slowly in a solution of HCl
acting on zinc in the presence of platinimi. n/10 NH4OH has
no visible effect while the equivalent concentrations of BaOH,
NaOH and KOH produce a violet lavender color only — vindicat-
ing, no doubt, the formation of methylene azure.
Neutral glucose solutions ranging from 1 to 10 per cent and
faintly or deeply colored with methylene blue are not decolorized
CHEMICAL CRITERIA OF ANAEROBI08IS 9
during thirty minutes in a boiling water bath. The same is
true of 2 per cent Witte's peptone solutions and of 2 per cent
agar solutions. Neither does the addition of 0.5 per cent glucose
to any of the acid solutions mentioned above result in decolori-
zation on heating; likewise 2 per cent agar and 2 per cent Witte's
peptone in graded hydrochloric acid solutions up to n/10 for
agar (which fails to solidify), and up to n/2 for peptone, refuse
to decolorize on heating. The neutral sodium salts of the above
acids formed by adding equivalent amoimts of standardized
NaOH do not alter the result; none decolorize on heating.
On the other hand an extremely small excess of alkali causes
the heated glucose, agar or peptone solution of methylene blue
to lose its color completely. Even such traces of alkali as may
be dissolved from the glassware may cause the decolorization of
methylene blue in glucose solutions on heating. Incidentally
we recall that Laird (1913) foimd the reaction time for Fehling's
solution reduced by boiling glucose, laevulose, galactose, maltose
and lactose in various makes of German glassware, owing to the
abstraction of calcium hydroxide from the glass. All experi-
ments reported herein were made with glassware carefully cleaned
with chromic acid cleaning fluid and rinsed in distilled water.
The use of such weak concentrations of alkali, which were approxi-
mated only by dilutions of standardized n/1 solutions, involves
the possibihty of other factors of error, as for example, atmos-
pheric CO2 and non-neutral distilled water, which do not enter
so fully with higher concentrations. Repeated tests of the
distilled water by colorimetric tests with phenolsulphonephthalein
showed the limits of pH value to be 6.8 and 7.0; thus this possible
factor of error was excluded. The COs factor of error was
reduced as far as possible by the use of freshly boiled distilled
water for the preparation of solutions and checked as a disturbing
factor in the interpretation of results. The great difficulty in
adequately and exactly controlling the very slight alkalinity of
the solutions in dififerent experiments without the use of buffer
substances may accoimt for some nonsignificant discrepancies
between the results with high dilutions of alkali in different
tests. It should be made quite clear that decolorization of
10
IVAN C. HALL
alkaline methylene blue solutions in the presence of these certain
organic ingredients of cultxure media is quite independent of the
presence or absence of the acid ions mentioned.
Neutral and n/20 HCl solutions of 1 per cent levulose, glucose,
lactose, maltose, sucrose, raffinose, inulin, dextrin, mannitol and,
dulcitol, (all Merck's highest piuity) , with 0.00005 gram meth-
ylene blue were tested also for decolorization by heating in a boil-
ing water bath for ten minutes, with negative results. Glucose,
TABLE 1
Correlalion of Fehling*8 teat and decoloruation of methylene hlite hy alkalinized
evgar solution
BSDuonoir
N
FBnLINO*8
TBBT*
Levulose.
Glucose..
Lactose..
Maltose. .
Sucrose. .
Raffinose.
Inulin. . .
Dextrin..
Mannitol.
Dulcitol.
ir/SNaOH
N/lOONaOH
N/lOOONaOH
NIUTBAL
N/aoHCi
+
+
—
.«
+
+
—
—
+
+
—
—
+
• +
—
—
+
—
.—
—
,
+
—
—
—
+
—
—
—
—
•, —
—
—
—
+
+
?
?
* Quoted from Hawk-Practical Physiological Chemistry. Blakiston, Phila-
delphia, 1907.
Reduction indicated by +•
No reduction during ten minutes in boiling water bath indicated by — .
levulose, lactose, and maltose solutions decolorized methylene
blue, however, in one or two minutes in n/1000 NaOH, but
raffinose, inulin and dextrin solution required n/100 NaOH
while sucrose, mannitol, and dulcitol, failed to decolorize meth-
ylene blue in even n/3 NaOH.
These results with ten representative carbohydrates of repu-
table purity suggested the following attempt to correlate meth-
ylene blue reduction with that of copper sulphate in Fehling's
test as in table 1.
There is apparently a well defined correspondence between
those carbohydrates whose reducing action is shown in Fehling's
CHEMICAL CRITERIA OF ANAEROBIOSI8
11
test and those which reduce methylene blue in n/1000 NaOH.
These carbohydrates are also most susceptible to alkaline-
hydrolysis. The trisaccharid raffinose and the poly-saccharids
inulin and dextrin are generally considered not to give Fehling's
test; they are less easily hydrolysed by alkalis, and they require
therefore a stronger concentration of alkali to reduce methylene
blue. The disaccharide, sucrose, and the alcohols, dulcitol and
mannitol, are especially resistant to alkalis: they respond there-
fore to neither Pehling's nor the methylene blue test. But
preliminary treatment of sucrose with n/100 HCl readily hydro-
lyses it and the overneutralization of such a mixture to n/100
alkalinity causes it to decolorize methylene blue quickly on
heating.
Quantitative relations
In many of the experiments up to this point the importance
of quantitative relations was recognized.
We have just seen that a minute quantity of alkali (n/1000
NaOH) suffices to insure decolorization of certain carbohydrates
in 1 per cent solution with 0.00005 gram methylene blue per
cubic centimeter. The rapidity of decolorization of glucose
solution varies according to the concentration of alkali, which,
if sufficiently strong, effects the destruction of color without
heating: furthermore, less alkaU is required to effect the loss of
color under anaerobic conditions than in the presence of the air.
The following is abstracted from a protocol covering an experi-
ment with 1 per cent glucose, 1 : 10,000 methylene blue, of vary-
ing degrees of alkalinity as indicated, placed in constricted tubes
with marble seals and read after twenty-four hours incubation
at 37*^0. without preliminary heating.
TUBS NUM BBB
NaOH
▲BOVB IIABBLB
BBLOW IIABBLB
1
2
3
4
N/60
N/120
N/240
n/480
4
Nearly colorless
Blue
Blue
Blue
Slightly yellow
Colorless
Nearly colorless
Blue
12 IVAN C. HALL
On boiling five minutes all were decolorized above and below
except tube 4. This experiment thus illustrates not only the
point just mentioned but also our frequent observation that
very weakly alkaline solutions are likely to fail to decolorize if
allowed to stand exposed to the air long before use, probably
owing to neutralization by CO*. This is a point to which we
shall return.
As to variations in dye content with n/1000 NaOH and 1 per
cent glucose, 1:1000 and 1:10,000 methylene blue failed to
decolorize in this particular experiment while solutions contain-
ing 1:100,000 did so. The weaker the concentration of dye,
the less alkali is required.
With n/1000 NaOH and 1:10,000 methylene blue variations
in glucose from 0.15 to 20 per cent appeared to make little or
no difference in decolorization, yet further dilution and variations
in alkalinity and dye content showed distinct effects, to which
reference will now be made for it is apparent that the three
reagents necessary in a test for the decolorization of methylene
blue by heating bear a definite quantitative relation, one to
another. Briefly, the amount of alkali required bears an inverse
relation to that of glucose but the necessary amounts of these
two reagents bear a direct relation to that of methylene blue.
The more alkali the less glucose is required and vice versa, but
the more methylene blue the more glucose or alkaU is requked.
Those relations are best displayed in the following experiment:
For the purpose of this and several similar experiments a
copper water bath with a support providing for 10 rows of 10
perforations each to hold test tubes was used. The tubes were
of imiform size as to length and bore; they were carefully cleaned
and placed in the support in rows corresponding to the record
marks of table 2, one tube for each mark. To each were first
added 7 cc. neutral distilled water and 1 cc. of an aqueous meth-
ylene blue solution 10 times the strength required in that particu-
lar section of the experiment. Solutions 10 times the strength
of glucose required in each of the vertical rows and of sodiimi
hydroxide in each of the horizontal rows were prepared and of
these 1 cc. each was added to each tube in the test. In such
CHEMICAL CRITERIA OF ANABROBIOSIS 13
an experiment it is always important te add the alkali last to
avoid any considerable action of a concentration greater than
that indicated by the recorded data. The total volume of liquid
in each tube was 10 cc.
The support with the tubes was then placed in the bath filled
with boiUng water and the boiling contmued for ten minutes,
when the support with the tubes was removed and the color or
lack of color in the solutions recorded. The reading was repeated
five and fifteen minutes after removal from the bath.
To facilitate the manipulation and observation of so many
tubes when an important time element is involved it was neces-
sary to divide the experiment in point of time into three sections
corresponding to the different quantities of methylene blue used;
conditions were duplicated as far as possible in each section with
the exception of the quantity of dye, even to the use of dilutions
from identical solutions of the three reagents. Also while the
data submitted were secured during the space of one afternoon,
the tests were repeated several times on other occasions with
essentially similar results.
The lines drawn in table 2 indicate the division at each reading
between those tubes showing definite color and those not showing
color. Next the line' on the colored side there were always tubes
partially decolorized. As the tests were exposed to room temper-
ature and the air the division line had to be moved in the direction
of stronger alkali and stronger glucose, in short, those solutions
containing least sugar and least alkali were last to decolorize
and first to regain their color.
Table 2 shows also that larger quantities of glucose and alkali
are required for the decolorization of a larger quantity of meth-
ylene blue and, further, that a decrease in alkaU is compensated
for by an increase in glucose. Roughly, within certain limits a
five-fold increase in glucose permits halving the alkali and vice
versa; It is not difficult to understand the direct correspondence
between the amount of dye decolorized and the amounts of
glucose and alkali required upon the theory that a definite quan-
tity of some substance or substances produced by the action of
alkali on glucose and other susceptible carbohydrates is necessary
14
IVAN C. HALL
as a matter of chemical equivalence but an attempt to apply the
Guldberg-Waage mass law was not successful.
The present status of our knowledge of the changes which
monosaccharids undergo in the presence of alkalis^ so well siun-
TABLE 2
Decolorization and recolaration of varying concentrations of methylene blue in
relation to varying concentrations of glticose and alkali
NaOH
MSTHTLBNX BLUK 1:1000
BBMABKB
•
N/100
0.004
0.02
1 +
.1 +
+
+
After 6 minuteB
N/200
0.1
1 +
+
' +
At once
N/400
N/800
N/1600
N/3200
0.6
1.0
2.0
Per cent glucose
MBTHTLXME BLUB 1:10,000
^
N/100
0.004
1-
( +
+
+
+
After 16 minuteB
N/200
0.02
1 +
,1 +
+
+
After 6 minutes
n/400
0.1
1 +
+
+
At once
N/800
N/ieoo
N/32D0
0.6
+
1.0
2.0
Per cent glucose
MBTHTLBlfS BLUB 1: 100,000
N/100
0.004
+
+
1+ .
1 +
+
+
+
N/200
+
+
1 +
After 16 minutes
n/400
+
+
+
n/800
- L
+
1 +
After 6 minutes
n/1600
0.02
- L
+
+
N/3200
0.1
0.6
1+
At once
1.0
2.0
Per cent glucose
— indicates no reduction — a blue solution.
+ indicates reduction — a colorless solution.
marized by Woodyatt (1915, 1918), indicates a tremendous
variety of reactions according to the sugars concerned, the con-
centration of hydroxyl ions, degree and time of heating, presence
CHEMICAL CRITERIA OF ANAEROBIOSIB 15
and absence of air, etc. In general, the basis laid by Lobry de
Bruyn (1895), Lobry de Bruyn and Van Ekenstein (1895, 1896,
1897) Nef (1907), Mathews (1909), Henderson (1911), Glattfeld
(1913), and others, indicates two groups of products resulting
from alkali treatment, first, isomers as a result of the action of
weak concentrations, low temperature, etc., and second, split
products as a result of stronger concentration and higher temper-
ature. Weak alkalis are transformative, strong alkalis destruc-
tive. The literature indicates clearly that glucose ionizes in
the presence of alkali as a weak acid, which can be readily shown
by colorimetric determination of the change in H~^ ion con-
centration of alkaline buffer solutions to which glucose is added.
AlkaU upsets the stability of the molecule causing the formation
not only of all the possible isomers, but of metallic glucosates,
and sugars of one, two, three, foiu*, and five carbon atoms as
well as oxy-acids.
The fact that decolorization occurs in the presence of minute
quantities of alkalis might seem to speak strongly for some isomer
as responsible for decolorization. But since isomers as well as
the original sugar are destroyed by higher concentrations of
alkali and these decolorize more readily than low concentrations
we cannot entertain this idea seriously. Also the decolorization
of methylene blue in similar concentrations of glucose and levulose
depends upon identical concentrations of alkali; thus 0.1 per
cent solutions of these sugars were decolorized in n/800 NaOH
but not in n/1600 NaOH during ten minutes boiling.
Similarly the temptation to explain the possible reduction of
alkalinity in the test almost to the vanishing point, by increasing
the glucose content, as a result of the adulteration of glucose with
effective isomers or split products is checked by the observation
that even 20 per cent solutions of glucose without alkali faU to
decolorize methylene blue on prolonged boiling.
On the other hand we are unable to exclude split products as
the effective agency when alkaU is present. Methylene blue
solutions caramelized by boiling a few minutes in n/10 or stronger
NaOH, and, when neutralized or even slightly acidified, and
allowed to regain their color (yellow + blue = green), can be
16 IVAN C. HALL
decolorized (yellow) in this condition by further boiling; further-
more, prolonged boiling of glucose, levxdose, and lactose in strongly
acid solutions also results ultimately in more or less complete
decolorization of methylene blue.
Some of the organic acids were noted above as failing to furnish
conditions necessary for the decolorization of heated methylene
blue solutions even in the presence of glucose. Alone in n/10
concentration, neutralized with equivalent amounts of n/10
NaOH, and alkalinized to n/10 NaOH, they also fail. Neither
formaldehyde, a building stone of glucose, nor ethyl alcoh(d,
one of the most frequent fermentation products of glucolysis,
in 5 per cent solution, acidified with HCl to n/10, neutral, or
alkalinized to n/10 NaOH, causes the decolorization of meth-
ylene blue solutions containing 1 part per 100,000 on boiling.
Other products of alkali glucolysis must be tested if we are to
fasten the responsibility for the decolorization of methylene blue
upon a definite single substance. Our present speculations lead
us to suspect that decolorization of methylene blue depends upon
those conditions which liberate nascent hydrogen and, that the
formation of metallic glucosates by alkalis is somewhat analogous
in this respect to the action of HCl on zinc. Or, it may be that
the hydrogen required for the reduction of methylene blue to
its leuco-base is derived from the dissociation of water and corre-
sponds to the equivalent oxygen uniting with the residue of the
sugar molecule, according to Nefs theory.
Two per cent Witte's peptone solutions and 2 per cent agar
solutions with 1:100,000 methylene blue are decolorized by
heating with alkali. But with peptone, at least 1 part n/1
NaOH in 128 had to be present, owing pos^bly to the consider-
able buffer action of peptone. With agar solutions (pH = 7)
decolorization occured with I part n 1 NaOH per 200 agar but
not with 1 part per 250, although agar is supposed to have little
w no buffer action according to Clark and Lubs (1917). Addi-
tion of 0.5 per cent glucose did not permit decolorization in less
alkali than in controls without glucose, in fact the presence of
agar inhibits decolorization in concentrations of alkaline glucose
scrfuticm which will readily decolorise without the agar.
CHEMICAL CRITERIA OF ANAEROBIOSIS
17
In the decolorization of methylene blue temperature is a factor;
heat plays a double r61e, driving out oxygen by lowering the
solubility point and accelerating the chemical reaction between
alkaU and organic matter.
Sunlight also effects the decolorization of methylene blue but
this factor is mentioned here only as a disturbing influence which
has been avoided in the experimental work. Lasareff (1912)
and Gebhard (1912) have shown that the bleaching effect of
light is most intense in the absence of oxygen; the color returns
in the dark in the presence of oxygen providing exposuce was to
wave lengths less than 620 mm but otherwise does not.
Table 3 displays the results of an experiment showing that
the return of color to decolorized methylene blue agar in bright
sunlight is considerably less rapid than in diffuse light or in the
dark.
TABLES
Depth of colored band at top of i per cent agar UDith n 1100 NaOH at different time
intervcde after decolorization ^ in varying light intensities
AITKR rOLLOWOfO NUMBKB OF MlNtmS BBlfOTAL WttOU BATH:
15
80
45
60
120
180
240
300
SimliKht
IHIfl*
0.5
0.5
0.8
ffiffi.
0.6
1.1
1.5
fflfll*
1.0
2.0
2.1
fllffl*
1.5
2.5
3.0
fflffl.
2.6
3.8
4.1
fflfll*
3.4
5.0
5.2
fflffl*
4.1
5.5
5.6
fllffl.
4.9
Diffuse>liKht
6.0
Dark
6.2
As to the decolorization of methylene blue by living cells this
discussion does not particularly concern itself further than to
note with Jordan that "anaerobes will grow in media where
. . . . reduced methylene blue shows no trace of reoxida-
tion." They will grow also in undecolorized methylene blue
but observations of many tests have shown no instance where
such growth was unaccompanied by decolorization. While, as
Ricketts (1904) has mentioned, we cannot regard the reduction
of methylene blue as a definite test for living cells, as Ehrlich
and others have suggested, since methylene blue becomes leuco-
methylene blue when its aflSnities for hydrogen have been satis-
fied, whether through reduction by living or non living matter,
IS IVAN C, HALL
yet in the known absence of non living reducing agents^ the
decolorization of methylene blue in culture media may be taken
as a fair indication of anaerobic growth where the conditions of
anaerobiosis are such as not in themselves to decolorize the dye.
The failinre of certain streptococci to decolorize methylene blue
in milk as sherman and Albus (1918) found, appears to be a
matter of inhibition; it is interesting to note Brown's (1920)
observation that some of these forms will develop in the depths
of agar containing decolorized methylene blue but not in the
colored band near the surface; contrary-wise it is possible for
many organisms to grow aerobically upon media colored with
methylene blue without decolorization. The possible r61e of
adsorption of methylene blue by bacterial bodies in its relation
to true reducing processes stiU remams to be investigated.
Recoloraiion of methylene blue
Whereas we are able only to speculate as to the basic expla-
nation of these various phenomena a knowledge of them enables
us to guage correctly the concentration of ingredients in the use
of methylene blue as a criterion of anaerobiosis. Such use
depends, as already noted, upon the recoloration of decolorized
methylene blue in the presence of air, and the failure of recolor-
ation when air is excluded. But recoloration does not occur in
glucose solutions in alkah stronger than n/32 in which marked
caramelization has occurred, nor in peptone more strongly
alkaline than n/16, nor in agar sufficiently alkalinized to prevent
solidification; neutraUzation of such glucose solutions permits
recoloration, however (Yellow + blue = green).
As a general rule, the delicacy of methylene blue as a criterion
of anaerobiosis varies directly as the kind and amount of reducing
agent employed, and the temperat\u*e used to effect decoloriza-
tion, and inversely as the alkalinity of the solution. As shown
in table 2 those decolorized solutions last to lose their color were
first to regain it. In general a moderate concentration of glucose,
e.g., 0.5 to 2 per cent with a low concentration of alkali (n/500
to n/1000 NaOH) gives the best results for tests involving
CHEMICAL CRITERIA OF ANAEROBIOSIS 19
liquids; 2 per cent neutral agar, plus 1 part n: 1 NaOH per 100
is satisfactory for tests involving solid media.
There is a possible fallacy in the use of too weakly alkaline
solutions, namely, that on standing they cannot be decolorized
by boiling. By exposing all the seven possible combinations of
one, two, or all, of the three factors, glucose, alkali, and dye,
for forty-eight hours, and then adding those lacking in each of
six of these, it can be shown readily that only those originally
containing alkali deteriorate; that is, deterioration consists in
loss of alkalinity. The test solution must be freshly alkalinized,
though the glucose methylene blue or agar methylene blue may
be kept as stock solutions. Loss of ability to decolorize might
conceivably be attributable to acid in the glassware though I
have never encountered this factor knowingly. The change of
reaction is most reasonably attributed to absorbtion of atmos-
pheric carbon dioxide. An easy proof of change in reaction of
faintly alkaline solutions on exposure to air is afforded if one
heats n/1000 NaOH colored with phenolphthalein in a con-
stricted tube with marble seal in a bath of boiling water; this dye
is not affected by such heating. But on cooling for several hours
the color above the marble fades while that below remains. Or,
drawing air through such a colored solution causes it to fade,
through change of reaction, but if the air be washed by bubbling
through several tubes of strong lye to remove CO2, with the
efficacy of such removal tested by passage through clear lime
water, the phenolphthalein test solution remains alkaline. A
repetition of this last experiment with a decolorized methylene
blue solution gives the same result, i.e., recoloration, with air
containing CO2 and air freed therefrom, except that the solution
recolorized with the latter continues susceptible to repeated
decolorization longer than with the former. Thife proves that
COj is not the only factor in recolorization of methylene blue
as it is in the change of reaction in the phenolphthalein experi-
ment. If the air be carefully washed in several successive
mixtiu-es of alkaline pyrogallol so as to remove both carbon
dioxide and oxygen its passage through a decolorized methylene
blue solution does not cause the return of color. In short, there
20 IVAN C. HALL
are two possible factors in the recoloration of methylene blue
by exposure to air, oxygen and carbon dioxide — two processes,
oxidation and acidification.
Since the reaction rests unquestionably upon a quantitative
basis, even though we know nothing of the absolute values in
oxygen and carbon dioxide concerned, the volumes of test solu-
tion in relation to surface exposure, where time marks the progress
of recoloration, is of great importance in comparative tests.
With equal surface exposure large voliunes regain their color
more slowly than small volumes. In all cases care has been
taken to use the same size tubes and identical volumes in a
given experiment imless otherwise stated. Dififerences in volume
between experiments account readily for certain apparent dis-
crepancies in actual observations of time required for recoloration.
AppUcalion to methods of culture
With these data at hand tests have been made of a great many
methods of cultivation, in which connections I gladly acknowl-
edge the aid of my student, Miss Margaret Eakin. Here, as in
the culture of anaerobic microorganisms, we have to distinguish
between the factors of oxygen tension reduction and of reduced
oxygen tension maintenance.
We have referred already to the literature on biological reduc-
tion of methylene blue; to this we may add that our experiments
show the general possession by Uving cells of the property of
reduction. This property is common to many aerobes and
anaerobes, so in sjrmbiotic mixtures, methylene blue is reduced
as a matter of course. With a broth culture of hay bacillus in
an external rubber stoppered tube and a smaller internal tube
containing slanted 2 per cent agar with 1:100,000 methylene
blue and n/100 NaOH analogous to the method of Salomonson
(1889), only partial reduction was obtained in twenty-four
hours at 37°C. and similar tubes of nutrient agar inoculated with
B. botulinu^, B. tetaniy B. wehhii and other obligative anaerobes
failed to yield satisfactory surface growth. Failure of complete
decolorization here is correlated with refusal of strict anaerobes
CHEMICAL CBITEBIA OF ANAEROBIOSIB 21
to multiply. This method is well known to be adapted to the
culture of microphilic aerobes, however.
Plant and ammal tissues also reduce methylene blue in the
depths of liquid media. In one instance a piece of sterile guinea
pig kidney under mineral oil kept methylene blue decolorized
in its immediate neighborhood at 37^C. for 196 hours whereas
the control without tissue but with an equivalent depth of oil
was completely recolored in thirty minutes.
Many investigators, as already noted, have referred to the
decolorization of methylene blue by animal and plant tissues
as well as by various inert substances in culture media as indicat-
ing anaerobic conditions therein. Of these, Zinsser, Hopkins
and Gilbert (1015) recognized most clearly that we have to deal
here with another process in addition to reduction, namely
adsorption. They were imable, by extraction of animal organs,
to secure any reducing substance whatever apart from the tissues
and concluded that adsorption is mainly responsible for the loss
of color in media containing methylene blue in the presence of
such agents. This conclusion was strengthened by their obser-
vation that heated tissues are nearly, if not quite, equal to
imheated tissues for this purpose. Similar observations were
previously made by Wrzosek (1907), Liefmann (1907), Guillemot
and Szczawinska (1908), and Hata (1908) but it is doubtful if
any of these workers appreciated the important rdle of adsorption.
It is possible, as I shall show presently, to extract reducing
substances from both plant and animal tissues, and in this
important respect their action upon methylene blue differs from
that of inert particulate substances such as sand.
When a small piece of potato was placed in an aqueous solution
of methylene blue (1 : 100,000) at room temperatiu'e, the solution
adjacent to the tissue lost its color withia two to three hours and
within a few more hours the test tube showed a lightly colored
bluish liquid in which the potato fragment was slightly tinged
with blue, most prominently at its uppermost end. No recolor-
ation occured in such a partially decolorized solution on exposure
in a Petri dish nor could it be decolorized by boiling except on
alkalinization. In contrast, the potato fragment became mark-
22 IVAN C. HALL
edly bluer on exposure, and if cut into displayed a decreasing
intensity of dye in the interior, the color deepening rapidly in
contact with the air. Such an experiment may be interpreted
as indicating adsorption plus reduction, the latter occurring
mainly, if not exclusively, within the plant tissue.
Acid (n/100 HCl) and alkaline (n/100 NaOH) solutions gave
similar results. Heating such a series immediately in the boiling
water bath resulted in decolorization of the alkaline solution
only. Exposed to the air in the tube the color returned to this
solution on cooling in an intensity practically equal to that of
the neutral and acid, solutions. Adsorption proceeded in all
three and did not seem to be notably accelerated by the heat-
ing. Previous boiling of the potato fragment seemed to have
no influence on the result.
Extraction by boiling a 1 gram fragment of potato in 1.0 cc.
of n/10 HCl, neutral water, or n/10 NaOH for ten minutes and
decanting the supernatant fluid yielded a solution containing a
reducing substance for methylene blue which could be demon-
strated by its decolorization on boiling in k/20 alkaline solution.
The color readily returned to such solutions on exposure to the
air in a Petri dish. The method of extraction suggested that
the substance extracted was probably starch which assumption
was substantiated by the iodine test. Starch reduces methylene
blue on boiling in alkaline solutions.
Experiments with animal tissues, such as rabbit and guinea
pig liver, in aqueous solutions of methylene blue gave results
apparently identical with those recorded for plant, i.e., potato
tissues. The solutions, acid, neutral and alkaline, became
decolorized in the inunediate neighborhood of the tissues within
a few hours and almost completely, throughout, in twenty-four
hours. The nearly colorless solutions separated from their tis-
sues did not regain their color on exposure to the air nor could
they be completely decolorized by heating except in the case of
the alkaline solution. Alkalinization of the neutral and acid
solutions, however, facihtated their rapid decolorization by heat.
The tissues became slightly tinged with blue during contact with
the dye solution and quickly colored on exposiu-e to the air,
CHEMICAL CRITERIA OF ANAEROBIOSIS 23
both on the surface and in the exposed depths. These phenom-
ena coincide exactly with those observed for the plant tissue
and point to the same two processes, adsorption and reduction.
But when it came to extraction of the reducing substance from
the animal tissues it was found that the solutions from freshly
boiled liver, whether acid (n/10 HCl), neutral, or alkaline (n/10
NaOH), failed to decolorize methylene blue added to them, even
when strongly alkalinized and heated further. Immediate
decolorization upon the addition of a trace of glucose proved
the suitabihty of the general conditions of the test for the proof
of a reducing agent. But kept in the ice chest overnight either
with or without previous boihng, and in acid, neutral or alkaline
solutions and then further boiled immediately previous to sepa^-
ration of the clear supemantant fluids, guinea-pig liver yielded
a reducing substance to the fluid capable of decolorizing meth-
ylene blue imder the influence of heat in alkaline solutions.
Guinea pig kidney also gave a similar result in neutral distilled
water; acid and alkaline extractions of kidney were not tried.
The results with these animal tissues differ from those with
potato, both in respect to the relative ease of extraction of the
reducing agent in the latter case, and probably in regard to its
chemical nature. There is little reason to doubt that the reduc-
ing substance extracted from potato is starch; the chemical
nature of that from the animal tissues is only conjectural. We
may say definitely that it belongs to the non-heat-coagulable
extractives, that it is not materially affected by relatively strong
acids and alkalis, and that it escapes from the tissue into the
solution during sixteen hours maceration in the ice chest or at
room temperatiu-e, with or without previous boiling. Further-
more, and this may be the point overlooked by Zinsser, Hopkins
and Gilbert (1915), a necessary condition for decolorization of
methylene blue by heat in the presence of either the reducing
substance from potato or that from rabbit and guinea pig liver
and kidney is an alkaline reaction. Solutions so decolorized
regain their color on exposure to air.
Thus in considering the action of such plant and animal tissues
in anaerobic culture media from the standpoint of their effect
24 IVAN C. HALL
on methylene blue we have to recognize that both adsorption
and reduction are concerned.
To complete a representative study of porous substances used
in the cultivation of anaerobic organisms I have selected white
sea sand. There has been a strong suggestion in such recent
work as that of Douglas, Fleming and Colebrook (1917) that
the principal value in plant and animal tissues added to cultiure
media for the cultivation of.obUgative anaerobes lies in their
provision of interstices which by their minute size serve to prevent
diffusion of oxygen as well as to afford secluded foci for the initi-
ation of growth, and this view has much to commend it. They
have shown, indeed, and others as well as ourselves have con-
firmed, the value of various inert insoluble substances added to
media in place of animal and plant tissue.
When I attempted the treatment of simple methylene blue
solutions with sand, results startlingly like those with tissues
were secured except that there was no reduction in the depths
of the sand. In brief, adsorption is the sole process concerned
here, and it occurs aerobically as well as anaerobically. In a
Smith fermentation tube filled with an aqueous methylene blue
solution and shaken up with sand which settled into the neck,
marked decolorization occurred in both the open and the closed
arms.
Of course it was impossible to ''extract" a reducing agent from
sand. But so far as the solution itself was concerned it behaved
exactly like that treated with tissue; with this exception, that
some reducing agent such as glucose, as well as an alkaline
reaction had to be provided in order to secure complete decolori-
zation by heating.
Whereas sand of itself has no true reducing action, there is no
doubt of its efficacy as a means of maintaining reduced oxygen
pressing, as we may judge from the persistence for many days
of decolorization in the closed arm of a fermentation tube pro-
vided with a slightly alkaline glucose solution of methylene blue
and a sand seal in the neck of the tube. The sand seal with
suitable cultiu'e media in the fermentation tube is also quite
satisfactory from the cultural standpoint.
CHEMICAL CBITERIA OF ANAEROBIOSIS 25
In summary, the di&erence between plant and animal tissues
and inert substances such as sand are the differences between
more or less soluble organic substances and insoluble inorganic
substances. No doubt, plant and animal tissues may serve the
same mechanical purposes as sand; in addition they may supply
nutrients to the medium, buffer substances and possibly even
''vitamins." . With plant and animal tissues in media, otherwise
lacking in reducing substances, these may be of supplementary
importance in the cultivation of obligate anaerobes. Finally,
unless we are willing to concede some importance to adsorbtion
as a factor in anaerobiosis, sand and other inert porous substances
may serve only as a means of maintenance of reduced oxygen
tension, i.e., as seals, whereas tissues may serve not only this
purpose but may actually aid in the reduction of oxygen tension
in addition to the nutritive functions they fulfill. We may
emphasize the importance of heat in this connection since the
existence of a true self active reducing agent as distinguished
from the phenomenon of adsorbtion seems as yet unproved.
As to physical reduction, i.e., ebullition, the data already
presented bear testimony to the efficacy of boiling. In these
tests, as in the actual culture of anaerobes, boiling is often an
essential preliminary procedure in the test. The use of both
liquid and solid deep media so decolorized shows the first return
of color at the top and proves the importance in the case of
liquid solutions, of such factors as narrowness of bore in the tube
volume of solution, the effect of diffusion currents, etc. With
solid media these are not so important.
In 1, 2 and 3 per cent agar^ with n/100 NaOH and 1:100,000
methylene blue, decolorized by boiling in standard culture tubes
of 1.5 cm. bore, the depth of the blue band at the top of the
agar at various intervals appeared as in table 4.
Apparently variation of agar content, within the Umits of
1 to 3 per cent makes only a little difference in the rate or depth
of recoloration. We may point out that the depth of blue color
at the top of the agar coliunn corresponds roughly to that in a
deep glucose agar stab or shake culture which is free from growth
though there are doubtless variations according to species, and
26
IVAN C. HALL
perhaps nutrient conditions, as Burke (1919) has mentioned.
On standing longer the blue band thickens, and it is suggested
that the distance from the surface at which anaerobic growth
commences is determined partly by the rapidity of multiplication
permitted by the nutritional conditions of the culture.
Deep tubes of agar, in which recoloration of decolorized meth-
ylene blue is occiu'ring, present the phenomenon of rhythmic
banding, i.e., liesegang's rings. This subject has been studied
recently by Holmes (1918) in other cases, but no one, so far as
I am aware, has investigated the phenomenon in the case of
methylene blue, for which no really satisfactory explanation is
available.
TABLE 4
Depth of returning blue hand in decolorized methylene blue agar of varying denaities
MINXITXB
AOAX
6
10
20
80
40
flO
percent
ffifyi.
ffifn.
Wwweww»
fiifiis
mff§.
^ww^«
1
0.4
0.6
0.6
1.8
2.6
3.3
2
0.4
0.6
0.7
1.8
2.6
2.8
3
0.6
0.8
0.8
«
2.6
3.6
4.6
HOUBS
AOAB
1
2
4
10
21
percent
rnwnm
mm.
mm.
mmm
w»lfl»
1
3.6
5.6
7.6
11.2
16.5
2
3.2
6.3
7.2
11.0
16.0
3
5.0
7.6
10.0
14.0
19.8
Other methods of deep culture involving solid or semi-solid
media present phenomena analogous to those observed with
deep agar tubes. Thus gelatin and deep brain media with
methylene blue remain decolorized in the depths for several
days after heating but the immediate coloration in the upper-
most layer gradually extends downward as oxygen and carbon
dioxide are absorbed. Corresponding to the usual failure of
cultural tests with unprotected liquid media, alkaline glucose
solutions of methylene blue regain their color on exposure to
CHEMICAL CRITERIA OF ANAEROBIOSIS 27
air soon after boiling. But large flasks of solution or very
slender deep tubes of such decolorized solutions remain decolor-
ized for some hours — sufficiently long, indeed, for anaerobic
growth to be initiated in suitable media heavily inoculated under
similar circumstances. In the Smith fermentation tube efficacy
for anaerobic culture, or maintenance of decolorization of meth-
ylene blue, depends largely upon the bore at the bend and satis-
factory results for either cannot be secured without the use of
a special seal, silch as sand, tissues, etc. In some unprotected
tubes the color returned to the solution in the closed arm in
fifteen minutes, in others in sixty minutes and in still others
after several hours; with sand seals the dye color returned only
in the open arm and then gradually faded even here through
adsorption.
The method of deep colony culture between the nested halves
of a Petri dish when tested with methylene blue showed a progres-
sive recoloration of the decolorized dye from the periphery inward,
except when protected by a paraffine or vaseline seal.
There is no phase of the methylene blue problem to which
we have given more careful attention than its use in connection
with insoluble Uquid seals, i.^., hydrocarbon oU, wax and grease.
The widespread use of these substances as a means of excluding
oxygen together with the theoretical and practical objections to
their use, especially in the case of oil, have justified a searching
examination of this matter. The results with methylene blue
only serve to support the conclusion that liquid hydrocarbons
are to a degree superfluous and inefficacious means of maintam-
ing anaerobiosis; on the other hand the waxes and semisolid
grease seals are more satisfactory for certain purposes, from the
standpoint of air exclusion, though inferior to mechanical seals
in the matter of convenience and cleanliness.
In the first place an alkaline glucose solution of methylene
blue does not decolorize at 37°C. under 2.5 cm. depth of mineral
oil, although it may be mentioned here that it does so readily
in a few hours under the marble seal in a constricted tube, or
under a cover slip in a plain tube, or under a thm layer of paraffine.
I have shown repeatedly with different samples of mineral
28
IVAN C. HALL
oil that the color returns to alkalme glucose methylene blue
solution decolorized under varying depths of oil by heatmg in
a boiling water bath almost as soon as without the oil. The
following instance illustrates this point. Two per cent glucose
(Pfanstiehl) with n/500 NaOH and 1:100,000 methylene blue
(Grtibler) in aqueous solution was placed in equal depth (3 cm.)
in similar culture tubes of ^ inch diameter and covered to the
depths noted with "Pulmor" oil, a white neutral mineral oil
prepared by the Fuller Morrison Company of Chicago; a con-
stricted tube with the same dye solution and marble seal was
included for a control. It should be noted that the diameter
of this tube was about twice, and the surface exposure of liquid
therefore 4 times, that of the other, thus offering even greater
opportunities for rapid recoloration, which was observed above
the seal. All were decolorized throughout by heating two
minutes in the boiUng water bath and readings made as f oUows
on the removal therefrom.
DKPTH OW on.
ONB-QUABTSB
HOUB
ONE H0I7B
TWO HOUB8
BIXTBBN ROUBS—
(boilbd TBN
MINUTBS)
cm.
5
Colorless
Slightly blue
Blue
Nearly color-
less
3
Colorless
Slightly blue
Blue
Nearly color-
less
1
0
Constricted
tube
Colorless
Slightly blue
Above — Blue
Below — Color-
less
Slightly blue
Blue
Blue
Colorless
Blue
Blue
Blue
Colorless
Slightly blue
Blue
•
* Not boiled with other tubes — still colorless below after six days.
This representative experiment indicates that oil is much less
efficacious than sometimes assmned as a means of oxygen exclu-
sion. The progressive ease of repeated decolorization in relation
to depth of oil suggests that carbon dioxide is excluded somewhat
better but one must not lose sight of the fact that the maximum
depth of oil in this experiment is much greatdr than ordinarily
used.
CHEMICAL CRITERIA OF ANAER0BI08IS 29
I have noted elsewhere (1915) that, oulturally, the growth of
obligative anaerobes is delayed under oil except where relatively
large inocula are used. In certain experiments, comparing the
efficacy of the marble and oil (2.5 cm.) seals in constricted tubes
with identical media, growth has been negative with the oil
seal in twenty^four to forty-eight hours at a million times the
dosage showing definite growth imder the marble. Continued
observation of the oil tubes has usually decreased the dispro-
portion, however. Although these experiments suggest an
inhibitive action of the oil this was not substantiated by com-
paring progressively diluted cultures under both the oil and
marble with a similar set under the marble only; in this case
equivalent dilutions developed in parallel order.
In this connection it was interesting to study the effect of
filling a constricted tube with alkaline methylene blue solution
and oil in such a way that the marble seal lay in the oil. The
results of a carefully controlled experiment are summarized
herewith, the solutions having been decolorized first in the usual
way by heating and removed for observation.
Ten minulea
Tube 1 — No seal Solution blue
I Blue above
Colorless below — remained so
for over two weeks.
Tube 3— Marble in oil Solution blue
Tube 4 — Oil alone Solution blue
Tube 3 in addition to showing this remarkable result also
shows regularly, in such an experiment, a strikmg and fairly
permanent emulsification of water in oil which has been made the
subject of a special monograph by the writer (1917).
But it was most disconcerting to find that the marble placed
in the oil fails to protect the decolorized solution from recolor-
ation on cooling and suggests that the effect of heating a solution
in contact with oil is to drive the oxygen from the solution in
which it is less soluble, into and possibly to some extent through
the oil, in which it is more soluble, and that on cooling there is
a return of some of the oxygen from the oil to the solution.
30 IVAN C. HALL
A duplication of this experiment using phenolphthalein instead
of methylene blue showed that COs also is probably similarly
concerned; for with the marble seal in the solution the alkalinity
of that portion below the seal was protected for over twenty-one
hours as against a failure above the marble but below the oil
within 1 hour, while with the marble in the oil the solution was
only faintly alkaline at one hour and frankly acid at three and
one-half hours.
It is impossible to attribute any change in reaction directly
to contact with the oil in view of an experiment with oil layered
on standard buffer solutions of known acidity (pH = 5, 6, 7, 8,
and 9) and colored with brom-cresol purple and cresol-red in
their respective ranges for comparison with identical solutions
with out oil; there was not the slightest evidence of changed
reaction either after shaking together cold, or during, or immedi-
ately after heating.
An attempt to make a better showing for the oil by heating
the mixture of alkaline glucose methylene blue solution in the
autoclave for twenty minutes at 26 pounds pressure (267°C.)
gave no better results. Neither was separate heating of solution
and oil either in the boiling water bath or in the autoclave,
followed by inmiediate layering, as efficacious in preventing the
return of color as heating together in the water bath.
Vigorous boiling of the solution under the oil by the cautious
«
use of a llO^C. saturated salt solution while accelerating the rate
of decolorization failed to show any material advantage in
excluding the air as judged by the time in which the color returned.
Several attempts to layer oil at or near its own boiling point
(about 300®C.) upon decolorized solution at lOO^C. resulted
disastrously in breakage of glassware and almost explosive
scattering of hot oil. Cooled rapidly to about 120°C. in a few
exeriments I had the gratification of seeing the solution under
the oil, even without the marble seal, remain completely decolor-
ized for nearly twenty-four hours; with the marble seal in the
oil it remained so for much longer. In still other experiments
where the oil was heated to boiling and allowed to cool even for
a few minutes, to as low as 60°C. and then immediately brought
CHEMICAL CRITERIA OF ANAEROBIOSIS 31
up to lOO^C. and layered upon the hot solution the color returned
to the latter in about half an hour as in the case of oil heated
with the solution in a boiling water bath.
If one increases the depth of solution in a tube without oil,
several times over that of a similar tube with oil, both being
equally decolorized by boiling, the former may be seen to regain
its color even before the latter.
These experiments lend little support to the use of oil as a
means of anaerobiosis and limit the technic where it is used to
layering on of freshly boiled oil quickly cooled nearly to lOO^C,
but even in this case it is less efficacious than the marble seal.
In none of the experiments with alkaline glucose methylene
blue solution has there been any evidence of absorption of the
dye by the oil. Methylene blue is insoluble in oil. A bluish
tinge sometimes observed in the oil layer is really due to the
dye dissolved in a film of water which separates the oil from the
glass wall as I have mentioned elsewhere (1917) or, in the case
of oil-dye solutions actively boiled over the free flame or in a
strong salt solution bath, to emulsified water holding the dye in
suspension. A suggestion that the dye might be absorbed in
the form of the colorless leuco-base was proven erroneous by
pipetting off the oil from the tube of decolorized dye solution
into a tube of distilled water; on exposure to air the color returned
at once to the original dye solution whereas the water and the
oil overl3dng it remained quite colorless.
Experiments analogous to some of those with the liquid solu-
tion have been performed with 2 per cent neutral agar made
alkaline by the addition of 1 cc. n/1 NaOH per 100 and colored
with 1 part methylene blue per 100,000 as offering a roughly
quantitative measure of the rate of air absorption which is indi-
cated by the thickness of the blue band that appears at the top
and deepens as exposure continues. Another advantage of this
means of test is that disproportionate volumes do not introduce
time differences into the observations of recoloration as they do
with a liquid test solution, yet in both cases the volumes and
areas exposed in different tubes have been kept identical for
comparative purposes except where otherwise noted.
32
IVAN C. HALL
The importance in such observations of having a sufficient
quantity of test solution is shown in the following experiment
which offers a comparison of the results with equal ratios but
differing absolute quantities of test solution and seal.
The liquid test solution was the usual 2 per cent glucose, with
N/500 NaOH, and 1:100,000 methylene blue; the agar test
solution was 2 per cent agar with n/1 NaOH and 1:100,000
methylene blue; the seal was vaseline. The mixtures were made
in tubes of 10 cm. diameter and heated in a boiling water bath
for a few minutes to decolorize. They were allowed to stand
overnight at room temperature and then examined for recolor-
ation. The results appear in table 5.
TABLES
Relation between absolute and proportional quantities of test solution and seal
VABELINB
BOLUTION
RB8ULT
II
VASKLXNS
80LX7TION
BBBUI/r
Liquid test solution
ce.
ce.
ce.
ee.
1
10
Colorless
1
10
•
Colorless
1
5
Colorless
2
10
Colorless
1
2
Blue
5
10
Colorless
1
1
Blue
10
10
Colorless
Agar test solution
1
1
1
1
10
5
2
1
Blue, 1 mm.
Blue, 1 mm.
Blue, 1 mm.
Blue
1
2
5
10
10
10
10
10
Blue, 1 mm.
Blue, 1 mm.
Blue, 1 mm.
Blue, 1 mm.
The logical explanation of this result appears to lie in the
assumption that sufficient oxygen or carbon dioxide is retained
in the seal to recolor a small amount of test fluid previous to
setting of the seal but not sufficient to recolor a larger amount.
Boiling an agar solution under 3 cm. of oil, in a water bath,
heating to 25 pounds steam pressure (267°C.) in the autoclave
for twenty minutes, or layering the separately heated oil and
agar solutions, made only a slight difference in the rate of return
of color at the oil-agar surface, which is almost as rapid as with-
out the oil.
CHEMICAL CBITERIA OF ANAER0BI0SI8
33
Neither heating the oil in the boiling water bath nor boiling
(about 300^0.) Over the free flame appeared to affect the density
of color in the superficial colored layers of alkaline, 2 per cent
agar containing methylene blue 1:100,000. This experiment
negatives the suggestion that de-aerated oil is able to abstract
oxygen and carbon dioxide from media containing them. Also,
whereas melted alkaline agar colored with methylene blue and
poured without further heating to decolorize into tubes, loses
its color to within 1 to 2 cm. of the surface in a few hours, the
immediate layering of such a solution with mineral oil makes
only a barely measurable difference in the thickness of the band
of color at the top.
TABLE 6
A com'pariion of mineral oH and paraffine as seals against the recolaration of cdkdline
methylene hlt^ agar
9
HOURS
0.25
2
«
24
45
70
95
No seal
em,
0.5
0.3
0.2
em.
0.7
0.5
0.3
em,
0.8
0.6
0.4
CM.
1.5
1.0
6.6
cm,
1.7
1.5
1.1
em,
2.0
1.9
1.1
em.
2.5
Mineral-oil
ParafBne
2.5
0.9
Depth of agar, 7 cm.
Depth of parafine and oil, 2.5 cm.
An equal amount of paraflSne in a similar tube, however,
reduced the band of undecolorized medium to 1 cm. in sbcteen
hours. In a comparison of these three conditions where boiling
was used as a means of immediate decolorization followed by
rapid cooling and incubation at 37^C., the measurements of the
blue band indicated (in centimeters) in table 6 were made.
An analogous comparison of parafiSne and vaseline of approxi-
mately equal melting points (50^C.) and boiling points (about
300°C.) showed vaseline to be superior even to parafiSne. Table
7 shows the actual measurements in centimeters (alkaline meth-
ylene blue agar 7 cm. deep).
The recession of the band under paraflSne and vaseline was
not peculiar to this particular experiment; it has frequently been
iOUBMAL OF BACTBBIO^OCnr, YOL. TX, NO. 1
34
rVAN C. HALL
seen, but never with oil nor in media without covering except
under the influence of light. It has a logical explanation, I
believe in the assumption that a certain limited amount of oxygen
and carbon dioxide are absorbed from the seal, thus accounting
for the band observed, but failure or reduction in the supply
coming through when the seal hardens permits the loss by diflfu-
pion from the lower surface of the blue band of these gases into
the deeper layers of medium and their dilution thereby to a
concentration insufficient to recolor the dye.
TABLE 7
A comparison of paraffine and vaseline as seals against the recoloration of alkaline
methylene blue agar
HOUBS
m
1.5
4
24
50
No seal
em.
0.7
0.6
0.2
em,
1.1
0.7
0.2
em,
2.0
1.3
0.3
em.
2.3
Parftff fie
0.7
Vaseline
0.0
Tests with the liquid solution also indicate the great superi-
ority of paraffine wax and especially vaseline over mineral oil
as a means of protecting decolorized methylene blue solutions
from recoloration. These compare favorably with the mechan-
ical seals such as the marble in a constricted tube, or the cover
glass in either plain or constricted tube, or sand in a Smith
fermentation tube, under all of which the dye may remain water
clear for days.
The efficacy of these seals is not a matter of boiling points
since mineral oil has approximately the same boiling point as
paraffine. Furthermore, the lower boiling hydrocarbons such
as xylol (137^^ to 140^^0.) and heptane (95° to 100°C.) are even
less efficacious than mineral oil. Viscosity and consistency seem
to be the essential elements ; perhaps the ease with which vaseline
clings to the glass on hardening explains its superiority over
paraffine. The liquid oils probably permit the return of absorbed
gases but more particularly operate through convection currents
CHEMICAL CRITERIA OF ANAEROBIOSIS 35
which transfer gases absorbed at the air surface to the oil-medium
surface. Such convection currents are absent, of course, in the
solid waxes and semisolid greases.
These researches would be barren were we not able to affirm
the parallelism of cultural studies. As a matter of fact, dilution
experiments with such organisms as B. tetani, B. Welchii, B.
sporogenes and others confirm the great value of paraffine and
vaseline as compared with liquid mineral oil. B. tetani absolutely
failed to grow under either xylol or heptane, gave only delayed
turbidity under mineral oil and vigorous early gas production
imder paraffine. Yet none of these is germicidal for B. tetani
as shown by successful growth under the marble in a constricted
tube of glucose broth covered with them.
The great objections to vaseline and paraffijie are their mess-
iness and the fact that they do not provide sufficient variety
of oxygen pressures in the mediimi to meet the possible require-
ments of different organisms.
Boiling as a means of oxygen tension reduction is sometimes
used in methods where the air chamber is sealed either by fusion
of the glass outlet or by mechanical devices such as valves,
cocks, etc. Either method is satisfactory from the standpoint
of the persistence of the decolorized state of methylene blue
but is obviously superfluous for deep cultures and is inapplicable
to surface cultures for reasons easily apparent.
Evacuation by water pump to 58 cm. mercurial pressure with
immediate sealing of a constricted portion of the tube has never
sufficed to decolorize methylene blue 1:100,000 either with 2
per cent glucose and n/600 NaOH or 2 per cent agar and n/100
NaOH at ordinary room temperature in our hands. Nor have
we ever been able to secure surface growths of such obUgate
anaerobes as B. Welchii, B. tetani, B. oedematis and J?. botidinus
on the surface of solidified glucose agar by this means alone.
We are therefore forced to conclude that evacuation by water
pumps of such efficiency is of relatively little value alone as a
method of securing anaerobiosis. Higher evacuation might
yield more successful results.
36 IVAN C. HALL
The literature is notably deficient in accurate data on the
oxygen tension limits of anaerobic bacteria determined by vacu-
umetric methods. The lunit of 35 cm. Hg pressure for the
vibrion septique set by Rosenthal (1906) m liquid media is of
doubtful value when viewed in the light of the recent obser-
vations of Harris (1919) on the apparently high tolerance of
B. sporagenes for oxygen in liquid cultures as compared with
agar slopes.
While we have tested the effect of iuert gases in the case of
hydrogen and carbon dioxide, it is scarcely fair to consider the
results as necessarily corresponding to those obtained by cultural
methods where we conceive the action to be primarily physical,
since with methylene blue solutions we may also have chemical
reactions. Hydrogen, indeed, did decolorize cold solutions of
0.5 per cent glucose with n/500 NaOH and 1 : 100,000 methylene
blue slowly, and hot solutions already decolorized remained so
during fifteen minutes of active ebullition by hydrogen from a
Kipp generator loaded with zinc and sulfuric acid and purified
by passage through 10 per cent PhNOs and alkaline pyrogallol.
Fiuthermore when sealed the hot solution remained decolorized
till opened on the fomlh day while the cold solution showed only
a trace of color while sealed.
Passage of commercial carbon dioxide through similar solutions
of the dye for one horn' failed to decolorize the cold solution
although the hot solution remained decolorized during this part
of the experiment but soon regained the blue color after sealing.
Reheating these solutions failed to decolorize either of them,
without further addition of alkali. Here is a situation, which,
barring the known inhibitive action due to improper acidity
for certain organisms, might jdeld satisfactory results in the
case of certaiQ others, as Pasteiir found, without permitting a
satisfactory degree of alkalinity for the decolorization of meth-
ylene blue.
Coming now to the matter of chemical reduction of oxygen
tension, we conceive that in so far as regards reducing agents
in the medium, they have been suflSciently dealt with already,
and the necessity of recognizing limitations of time and space
CHEMICAL CRITERIA OF ANAEROBIOSIS 37
reduces this discussion, ia so far as it relates to chemical reduction
by means of an agent in the air chamber, to the most valuable
agent with which we have to deal, i.e., alkaline-pyrogallol.
Inasmuch as this reagent finds a legitimate use only in con-
nection with attempts to secure surface colonies on solid media,
it is to this that we have limited our attention. Buchner's
(1888) original technic involving the use of a small tube contain-
ing slanted culture medium (2 per cent agar, methylene blue
1:100,000, n/100 NaOH) in a longer one containing the usual
alkaline pyrogallol mixture gave satisfactory results when the
cotton stopper was left out of the inner tube, but otherwise did
not, unless the tube were inverted. Decolorization begins, as
does growth of obligate anaerobes on suitable media, in the
thinnest portion of the slant. In Wright's (1901) modification,
which involves the saturation of the plug with the mixture,
sealing by rubber stopper, and inversion, even better results
were obtained. In either case partial decolorization appeared
at the surface in less than twenty-four hours at 37°C. and con-
tinued to completion within two to three days. Both these
methods, but notably the last, have given quite satisfactory
results in the surface cultivation of B. tetani, B. welchii, B.
sporogeneSf B. chauveauii, B. botvlinuSy and many unidentified
anaerobes. Wright's method has been relied upon largely for
repeated surface colony isolation of the writer's ctiltures.
Two plating methods for surface cultiu'e have been studied
in connection with the methylene blue test, namely Lentz's
(1910) pyrogallic acid saturated cardboard, and McLeod's (1913)
divided plate. Both showed the dye-agar decolorized at 37^0.
within eighteen hoiurs. The letter method has refused consist-
ently however to yield us surface colonies of well known anaerobes
on either blood or glucose agar identical with that used in con-
trols by Wright's method. Dr. Oskar Klotz at the University
of Pittsburg has stated his belief that aromatic substances in
the clay are sufficiently germicidal to explain the failure of
bacterial growth and has overcome the difficulty through the
use of a special cement containing paraffine and some other
substances. At any rate, McCleod's device seems constructed
38 IVAN C. HALL
according to our best conceptions of the requirements. In con-
trast, the method of Lentz is open to the technical objection that
considerable absorption may occur before the seal is completed.
We have not tested the latter sufficiently from a bacteriological
standpoint to justify any conclusion as to its real worth. The
dye test points to its suitability.
In conclusion it is suggested that further studies are required
to show exactly to what degree of oxygen tension reduction the
decolorization of methylene blue imder stated conditions corre-
sponds. Harvey's (1919) recent demonstration of the direct
relation between oxygen content and time of decolorization of
methylene blue in Schardinger's test and the interesting parallel-
ism between methylene blue reduction and luciferin formation
(1920) is significant in this regard, but one must not overlook
the great importance of the hydrogen ion concentration of the
test solution, and the effect upon this of atmospheric carbon
dioxide.
Similar studies are equally needed in the investigation of the
oxygen relations of obligate anaerobic bacteria.
SUMMARY
This paper reviews the Uterature on chemical criteria of anaero-
biosis, and imdertakes a critical experimental survey of the sub-
ject in so far ai^ it relates to the use of methylene blue for this
purpose. The mechanism of the decolorization of methylene
blue is studied in detail and shown to depend upon the inter-
action of alkali and certain organic substances, notably carbo-
hydrates. A correspondence between Fehling's test and the
decolorization of methylene blue in alkaline solutions of various
carbohydrates is pointed out.
It is shown that while there is a direct relation between the
amoimt of dye decolorized by heating and the amoimts of alkali
and glucose, there is an inverse relation between the last two
factors in the test, so that an increase in one permits a decrease
in the other for the same result.
Carbon dioxide, as well as oxygen, is shown to be an effective
factor in the recoloration of decolorized methylene blue.
CHEMICAL CRITERIA OF ANAEROBIOSIS 39
Various methods of anaerobiosis are viewed critically in the
light of experimental tests with carefully balanced solutions of
alkaline glucose methylene blue in comparison with ctiltural
tests with B. Welchii, B. tetani, B. bolvMnuSj and other obUgate
anaerobes.
. A detailed study of the decolorization of methylene blue by
plant and animal tissues is described, showing the important
role of adsorption as a means of decolorization by these and
other porous substances. The extraction from plant and animal
tissues of reducing substances for methylene blue, active in
alkaline solution, is described.
The efficacy of deep culture methods for anaerobes is shown
while the inefficacy of insoluble liquid (i.e., oil) seals is contrasted
with the reliability of semi-solid waxes and greases, and that of
mechanical seals.
The short-comings of certain methods of surface culture of
obligative anaerobes are exposed and the value of a modification
of Wright's method upheld by these studies.
Finally, the desirability is indicated of determining exactly
to what degree of oxygen tension reduction the decolorization
of methylene blue corresponds, and whether decolorization occurs
at a definite hydrogen ion concentration irrespective of the sugar
content of the solution.
REFERENCES
Bebnkr 1904 On a vial for the culture of anaerobic bacteria on plates.
Centralbl. f. Bakteriol., 1 Abt. Orig., 87, 478.
Bbrnthsbn 1883 Ueber das Methylenblau. Berichte d. deutschen Chem
Gesellsch., 16, 1026.
1883 Zur KenntnisB des Methylenblau u. verwandter Farbstoffe.
Ibid., 16, 2896.
1884 Ibid., 17, 611.
1885 Studien in der Methylenblaugruppe. Liebig's Annalen der
Chemie, 280, 73, 137.
Brown 1920 Cultural differentiation of beta hemolytic streptococci of human
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BucHNBR, E. 1885 Ueber den Einfluss des Sauerstoffs auf Gfthruni^en. Ztschr.
f. Phys. Chem., 9, 380.
BucHNBR, H. 1884 Eine neue Methode zur Kultur anaerober Mikroorganismen.
Centr. f. Bakt., 1 Abt. Orig. 4, 149.
40 IVAN C. HALL
BuRKB 1019 Notes on B. hotuliniu. Jour. Bact., 4, 555.
Clabkb and Lubs 1917 The colorimetric determinflition of hydrogen ion con-
centration and its applications in bacteriology. Jour. Bact., 2, 109,
191.
DotTOLASB, Flbminq, AND CoLBBBOOK 1917 On the growth of anaerobic bacilli
in fluid media under apparently aerobic conditions. Lancet, 2,
590.
Eblbnmbtbb 1883 Zur Constitution des Methylenblau. Berichted. deutscben
chem. Geselbch., 16, 2857.
Frbiojn 1903 A note on the cultivation of anaerobic bacteria. Lancet, 1,
518.
1904 The plate cultivation of anaerobic bacteria. Ibid., 2, 824.
Febui and Babsit 1904 Untersuchungen Uber die Anaerobiosis. Centr. f.
Bakt., 1 Abt. Orig., 36, 553, 714.
Gbbhabdt 1912 Ueber das Ausbleichen von Methylenblau im sichtbaren
Spectrum. Ztschr. physik. Chem., 79, 639.
Glattfeld 1913 On the oxidation of glucose in alkaline solution by air as
well as by hydrogen peroxide. Dissertation, Univ. of Chicago.
Guillbmot and Szczawinska 1908 R61e des substance r^uctrices dans la
culture des ana^robies en prince de Pair. Comptes rend. Soc. bioL,
e4, 171.
Gunning 1877 Ueber SauerstofiFgasfreie Medien. Jour. f. prakt. Chemie.,
16, 314.
1878 Experimental Untersuchungen uber AnaSrobiose bei den F&ul-
nissbakterien. Ibid., 17, 266.
1879 Ueber die Lebensf&higkeit der Spaltpilse bei fehlenden Sauer-
' stoff. Ibid., 20, 434.
Hall 1915 A new aerobe-anaerobic culture tube. Univ. of Calif. Pub. in
Pathology, 2, 147.
1917 The stability of emulsions in the constricted tube and marble
device for anaerobiosis. Jour, of Physical Chemistry 21, 600.
Hammbbl 1901 Ein Beitrag zur Z&chtung der Anaeroben. Centr. f. Bakt.
1 Abt. Orig., aO, 658.
Habvet 1920 The action of acid and light in the reduction of cypridina oxylu-
ciferin. Jour. Gen. Physiol., 2, 207.
1919 Relation between the oxygen concentration and rate of reduction
of methylene blue by milk. Jour. Gen. Physiol., 1, 415.
Hata 1908 Ueber eine einfache Methode zur aSrobische Kultivierung der
An&eroben, mit besondrer BerUchsichtigung ihrer Toxin Produktion.
Centr. f. Bakt. 1 Abt. Orig., 46, 539.
Hendbbson 1911 The instability of glucose at the temperature and alkalinity
of the body. Jour. Biol. Chem., 10, 3.
Holmes 1917 Rhythmic banding. Science, 46, 442.
1918 Experiments in rhythmic banding. Jour. Am. Chem. Soc, 40,
1187.
«
Hunzikbb 1902 Review of existing methods for cultivating anaerobic bac-
teria. Jour. Applied Microscopy, 6, 1694, 1741, 1800, 1854.
Jobdan 1918 General Bacteriology, 6th ed., Saunders, Phila., p. 84.
CHEMICAL CRITERIA OF ANAEROBIOSIS 41
Eabbhbl 1809 Zur Frage der Zuchtung anaerober Bakterien. Gentr. f. Bakt.
1 Abt. Orig., 26, 555.
EiTASATO AND Weil 1890 ZuF KenntniBS der Anafiroben, 8, 41.
Laidlaw 1915 Some simple anaerobic methods. Brit. Med. Jour., 1, 497.
Laibd 1913 Action of sugar solutions on glass. Jour. Path, and Bact., 18, 32.
Landaubr and Wbil 1910 Studien Uber das Methylenblau. Berichte d. deut-
schen chem. Gesellsch., 48, 196.
Labarbff 1912 Ueber das AusblUchen von Methylenblau im Slchtbaren
Spektrum. Ztschr. physik. Chem., 78, 661.
LxNTC 1910 Ein neues Verf ahren fllr die Anaeroben ZUchtung. Centr. f . Bakt.
1 Abt. Orig., 68, 358.
LiBnfAN 1907 Ueber das scheinbar aerobe Wachstum ana£rober Bakterien.
MOnch. med. Wchnschr., 64, 823.
1908 Ein einfaches verfahren zur Ztichtimg und Isolienmg anaerober
Keime. Centr. f. Bakt. 1 Abt. Orig., 46, 377.
Lobby db Bbtttn 1895 Action des alcalis dilute sur les hydrates de carbone.
I. Rec. trav. Chim., 14, 156.
Lobby de Bbuyn bt Van Ekbnstbin 1895 Action des alcalis sur les sucres.
II. Rec. trav. Chim., 14, 203.
1896 Ibid.. Ill, 16, 92.
1897 Ibid., IV, 16, 257.
Mathbwb 1909 Spontaneous oxidation of the sugars. Jour. Biol. Chem.,
6,1.
McIntgbh and Fildes 1916 A new apparatus for the isolation and cultivation
of anaerobic microorganisms. Lancet, 1, 768.
1916 Nouvelle m^thode d'isolement et de culture pour les microbes
anaerobies. Comptes rend. Soc. biol., 79, 768.
McLbod 1913 A method for the plate culture of anaerobic bacteria. Jour.
of Path, and Bact., 17, 454.
M5HLAU 1883 Syn these des Methelenblau. Berichte d. deutsche chem.
Gesellsch., 16, 2728.
Nbf 1907 Dissociationsvorgfinge in der Zuchergruppe. Liebig's Annalen der
Chemie, 367, 214.
NovY 1893 Die Kulture anaerober Bakterien. Centr. f. Bakt., 1 Abt. Orig.,
14, 581.
Pbtei 1900 Neue anfierobe Gelatine-Schalenkultur. Centr. f. Bakt. 1 Abt.
Orig., 88, 196.
RiCKBTTS 1904 Reduction of methylene blue by nervous tissue. Jour. Inf.
Dis., 1, 590.
Rosenthal 1906 Culture a^robie du vibrion septique; Mensuration de
I'anaerobiose. Comptes rend. Soc. biol., 60, 874.
Sanivucb 1803 Untersuchungen Ober an&erobe Mikro-organism. Ztschr. f.
Hyg., 14, 339.
Sbllabdb 1904 Some researches on anaerobic cultures with phosphorus.
Centr. f. Bakt., 1 Abt. Orig., 37, 632.
Shbbman and Albus 1918 Some characters which differentiate the lactic acid
streptococcus from streptococci of the pyogenes type in milk. Jour.
Bact., 8, 153.
IT AN C. HALL
#
/
POWDERED LITMUS MILK
A PRODUCT OF CONSTANT QUALIT?- AND COLOR WHICH CAN
BE MADE IN ANY LABORATORY
HERBERT W. HAMILTON
Sanitary Research Labaraiaries, MassachueeUe InsHiute of Technology
Received for publication June 7, 1020
The wide use of litmus milk as a culture medium, due to its
great value in the differentiation of bacteria, has led to the
development of various casein media as substitutes. Canned
milk has also been used with varying degrees of success. This
paper presents a formula which insures a standard product.
Present practice requires the purchase of milk, whole or
skimmed. In the former case the fat has to be removed. When
the milk is finally prepared it is often f oimd to be too acid and
readjustment is required. After such a readjustment is made
the effect of sterilization of the milk is often detrimental. But
what is more important is the varying color of the milk with
every batch. It was with this fact in view that the present
formula was developed.
PREPARATION OF THE INDICATOR
1. The dye should be a blue azolitmin, as free as possible
from the red dye. This may be prepared by extracting litmus
cubes with boUing distilled water and decanting off the clear
solution. The liquid is evaporated to a thin paste over a free
flame and treated with an excess of glacial acetic acid. The
evaporation is now carried to dryness on a water bath. A
quantity of 95 per cent alcohol is added and the whole trans-
ferred to a filter. The residue is washed several times with
alcohol* The filtrate is discarded. Should the residue be left
reddish a drop or two of sodixun hydroxide solution will restore
43
^
^
44 HEBBERT W. HAMILTON
its color. The residue is dissolved in water. This is evaporated
to dryness, first over a free flame and finally on the water bath.
The yield is about one twenty-fifth of the original weight of the
cubes. (Azolitmin may be purchased from certain dealers.)
2. A satisfactory powder may be prepared by extracting the
cubes with hot water, filtering and evaporating the filtrate to
dryness. The residue is treated with 95 per cent alcohol over-
night. In the morning the alcohol is decanted off and the
residue dried on the water bath.
THE MILK
Skimmed milk powder is purchased from a bakers' supply
company or grocer. Care should be taken to see that it is
clean. Quantities in small containers are more satisfactory
than bulk purchases.
The litmus powder so prepared is mixed with the milk powder.
In the case of the litmus powder prepared by the first method
j(or purchased azoUtmin powder) one part of the dye is added to
52.7 parts of the skimmed milk powder. When the dye is
prepared by the second method one part of the dye powder is
added to 49.6 parts of the milk powder.
The resulting mixture is dissolved in distilled water in the
proportion of one part of the litmus milk powder to 9.5 parts of
water.
Care should be taken in the mixing that the litmus powder is
well ground and well dispersed in the milk powder.
All media made in this way have been steriUzed perfectly in
the Arnold SteriUzer. When autoclaved at 15 poimds for five
minutes the medium resumes its true color on cooling. The
mixed powder has kept perfectly in a glass stoppered bottle for
two years.
Cultures of BacL coli, B. Welchii, Bad. acidi4acticif Bact.
alcaligeneSf PseucUmionas fluoreacena, B. mesentericus-mdgatiis,
Staph, pyogenes-^ilbvs, and Proteiia vulgaris all grew well and gave
typical reactions in the normal time.
BACTERIA CONCERNED IN THE RIPENIN6 OF CORN
SILAGE
p. G. HEINEMAN and CHARLES R. HIXSON
From the Laboraiarie8 of the United States Standard Products Company
Receiyed for publication July 2, 1920
The production of silage on the farm may be regarded as a
means of conserving valuable food material. During the proc-
ess of fermentation which takes place in the sUo the fresh fodder
is so altered as to prevent spoilage and to conserve its food value.
Experience as well as experiment has shown that a highly nutri-
tious ajid palatable food is thus made available during the winter
months, when fresh fodder cannot be obtained.
The authors make no claim to have solved all the problems
connected with Hie fermentation of silage. Many details must
remain for future investigation and all that can be claimed is
progress. Hunter and Bushnell and Sherman lay stress on the
activity of lactobacilli in the ripening of silage and the present
work confirms the findings of these authors, namely that lacto-
bacilli are important factors, but that they probably reach the
maximum of their activity during late stages of fermentation.
Opportunity presented itself to investigate silage from three
silos. Two of these are constructed of ^ood with concrete
foundation, while the third is concrete throughout. The inves-
tigation, as might be anticipated, shows that although the fer-
mentative process in general is similar in different silos, it is by
no means identical. That is to say, after a definite lapse of
time the silage of one silo may be fermented in larger measure
than that in another silo. Furtherlnore, the same stage of
fermentation does not necessarily obtain throughout the same
silo. No relation to the difference in construction could however
be detected.
46
46 p. G. HEINEMAK AND CHARLES R. HIXSON
The silage in the three silos was removed from the top as it
was reqmred as food for cattle. Therefore the samples obtained
for investigation had not only fermented during progressively
longer periods of time, but since the surface layers were period-
ically removed samples had to be procured from increasing
depths. It is conceivable, therefore that anaerobic fermentation
becosnes more pronounced as silage ripens.
METHODS
Samples were taken from the silos in November, January,
February, March, April, May and June. A few days elapsed
between sampling the different silos in order not to crowd the
work but this short interval probably made no material dif-
ference in the relative stage of fermentation. Ten grams of each
sample were infused with 50 cc. of cold physiologic salt solution.
From this infusion stains were prepared and inoculations made in
milk with addition of brom-cresol-purple as indicator, into
flasks and fermentation tubes containing 2 per cent glucose
broth, and on agar. The last mediimi was used for siuface and
stab cultures. The infusion of silage was titrated with n/20
NaOH with phenolphthalein as indicator and then together
with the inoculated media was incubateki at 37^C.
RESULTS
Stains from the silage infusion showed enormous niunbers of
microorganisms. No attempt was made to enumerate them or
separate the types, but the predominating types were noted
and cultivated. Yeast cells were invariably present and fre-
quently formed a solid film on the surface of the incubated
infusion. The acidity of this infusion was never more than 3
per cent normal, but ti is probable that the salt solution did not
dissolve all the acid contained in the silage. If the juice had
been pressed from the silage and then diluted five times its
volume with salt solution the acidity would probably have
proved higher than the values obtained. After 24 hours incu-
bation of the silage infusion the acidity rose to about three
BACTERIA IN THE RIPENING OF CORN SILAGE 47
tiines the original amount, but after forty-eight hours a marked
decrease of acidity was observed coincident with the development
of a heavy film consisting of yeast cells.
A bacillus of the colon-a;erogenes group was present in large
numbers, but only in smears prepared from silage during early
stages of fermentation. During late stages the bacillus may
still have been present, but if so was numerically iosignificant.
Streptococci and lactobacilli were always present in early as
well as in late samples. The streptococci were readily isolated
by plating, but the lactobacilli did not grow readily on ordinary
media and were isolated by the method employed by Heineman
and Hefferan, namely by repeated transfers through milk and
final plating on whey agar.
The streptococci isolated varied somewhat morphologically.
In some cases the diplococcus form was predominant, while in
others chain formation was observed. However, the diplococcus
form was found chiefly in early samples of silage, while chain
formation was abundant in later samples. Chains were prom-
inent also in stock cultures prepared from the isolated strepto-
cocci, but the short form reappeared when fresh subcultures
were prepared. The fact has been repeatedly recorded, that
during 3ie most active period of growth, streptococci, especially
saprophytic ones, appear chiefly in diplococcus forln, while
after the maximuin growth has passed chain formation becomes*
more evident. The size of individual cells of streptococci con-
firms the assumption that they are more active in early silage
than in the ripened product. From early samples the c^s
were uniformly small and in later samples they were large and
frequently appeared swollen. These abnormal forms disap-
peared when yoimg generations grew on inoculated media.
The amount of acid formed in glucose broth by the strepto-
cocci was determined by titration with n/20 NaOH. The
quantity thus determined never exceeded 5 per cent normal
acid in five days. Milk was readily coagulated by most strains
of streptococci isolated, in some cases within twenty-four hours.
The lactobacilli observed occurred singly, showed granular
staining with methylene-blue in many instances and were rather
difficult to isolate. They grew slowly on media containing 2.
48 p. G. HEINEBfAN AND CHABLE8 R. HIXSON
per cent glucose and the colonies formed on whey agar were
always very small. However, from the latest samples a strepto-
bacillus was isolated which grew with relative abimdance on
glucose media and produced up to 11.5 per cent acid in glucose
broth in sue to seven days. This bacillus appeared in long fila-
ments composed of rather short baciUi. The acid produced
consisted chiefly of lactic acid. It shotild be emphasized that
this strepto-bacillus was never observed in early samples,
although it probably was present in small numbers.
Milk inoculated with two loopf uls of silage infusion coagulated
promptly, usually within twenty-foiu* hours and when inoculated
witii the infusion of early samples considerable amounts of gas
were produced. In some instances the gas formation was so
vigorous as to break up the coagulum. As ripening of the silage
progressed the amoimt of gas formed in milk decreased and
finally in the last stages of fermentation no gas appeared. Stains
from the coagulated milk, prepared after twenty-four hours incuba-
tion, showed that in early stages organisms of the colon-aerogenes
group were present in abimdance, accompanied by large nmnbers
of streptococci, but as the ripening process proceeded strepto-
cocci became more prominent and finally were present practically
in pure ctilture. The milk cultures were not incubated for a
sufficient length of time to permit lactobacilli to supersede
streptococci, excepting when lactobacilli were searched for.
In a recent paper Gorini calls attention to the presence of
butyric acid baciUi in silage and warns of the possibility of their
influence on the product. Since anaerobic conditions obtain,
at least in deep layers of silage, and since the temperature may
be relatively high, conditions for the growth of butyric acid
baciUi are not unfavorable. Gorini suggests that the tempera-
ture be not permitted to go beyond 50°C. nor below 30®C. in
order to favor the growth of lactic ferments (lactobacilli and
streptococci) and thus antagonize butyric acid* bacilli. In our
limited investigation no evidence of the presence of butyric
acid baciUi was observed, although they may have been present
in smaU numbers. Several anaerobic cultures prepared from the
silage infusion invariably gave a growth of streptococci, prac-
ticaUy in pure culture.
BACTERIA IN THE RIPENING OF CORN SILAGE 49
DISCUSSION
As stated before the investigation reported in this paper does
not warrant very definite conclusions and the following sugges-
tions are offered tentatively. It is a well known fact that the
groups of colon-aerogenes bacilli, of streptococci and of lacto-
bacilli are widely distributed in nature and especially on fodder.
Lacto-bacilli were found by Heineman and Hefleran in commeal
and by Sherman on fresh com leaves. The presence of these groups
in silage may therefore be considered as established. This con-
dition recalls observations on the so-called normal souring of
milk and the activity of streptococci and lactobacilli during
cheese ripening. Assuming • that the colon-aerogenes group is
present in fresh silage a limited growth of these organisms would
produce an initial fermentation with acid and gas as the chief
products. This assumption is supported by the fact that con-
siderable pressure is developed during the ripening of silage and
by our observation that gas is formed in abundance in milk cul-
tures prepared from samples of sili^ge in early stages of ripening.
The colon-aerogenes group is soon suppressed by the strepto-
cocci. Acid is the chiief product of this group. Milk cultures
showed a progressive decrease of gas formation a fact which
indicates the gradual suppression of the colon-aerogenes group.
Streptococci are then crowded out by lactobacilli, but probably
never disappear entirely as they could be isolated readily from
silage in its last stages of fermentation. It is suggested that at
least two groups of lactobacilli are active. The first group is of
the slow-growing type, the baciUi occurring singly and showing
granular staining with methylene-blue. The second group of
lactobacilli is of the more rapid-growing order and is readily
isolated from later stages of fermenting silage.
Wyant inoculated corn silage experimentally with cultures of
Streptococcus lacticus and LactohaciU/us bvlgariciis and obtained
a product which according to the author's description resembled
normal silage. However, after a period of four to five weeks
lactobacilli were not isolated, while streptococci were recovered
without difficulty. This shows that the silage had not passed
50 P. 6. HEINEMAN AND CHARLES R. HIXSON
beyond the second phase of fermentation. According to the
investigation reported in this paper the third phase of fermenta-
tion, when lactobacilli are active, does not occur during the
first weeks of the ripening process.
The investigation came to a conclusion because the silage was
practically exhausted in the silos whose product was available.
The remaining 'silage contained considerable quantity of acid
and the owners of the silos hesitated to use this remnant for
fodder. It does not seem, however, that the acidity was great
enough to cause injury to the cattle. Fair samples could not be
obtained from these remnants.
It has been stated that stains from early samples of silage
showed the presence of large numbers of micro5rganisms of
various tj^pes. During the progress of the work the number of
types was gradually reduced and the microscopic picture of
stains from the last stages of ripening differed materially from
that obtained from early stages, inasmuch as streptococci and
lactobacilli were clearly predominant and other forms had dis-
appeared in very large measiu*e. No doubt the result is explained
by the accumulation of acid in the final product. The disap-
pearing bacteria may influence the ripening process by consum-
ing oxygen and thus create favorable conditions for facultative
anaerobes, such as streptococci and lactobacilli.
CONCLUSION
The authors as a result of this investigation offer as a tenta-
tive hyjwthesis of the ripening process of com silage the follow-
ing: The fermentation consists of three phases brought about
by three groups of bacteria. The initial phase is of short dura-
tion and is caused by members of the colon-aerogenes group of
bacteria. It is accompanied by acid and gas formation. The
second phase is carried on by streptococci and is accompanied
by moderate acid formation. The third phase is the result of
the activity of lactobacilli. The third phase may possibly be
subdivided into minor phases owing to the presence of different
strains of lactobaciUi. It should be added that the assmnption
BACTERIA IN THE RIPENING OF CORN SILAGE 51
of some investigators that the first process of silage ripening is a
respiratory process (Babcock and Russell) is not excluded by
the hypothesis advanced and does not interfere with it. Fur-
thermore, mention should be made of the fact that at no time
was growth of yeasts in the silage observed, although yeast
cells were invariably present. Growth of yeast was observed
only when an extract of silage was incubated at 37°C. There is
therefore in this investigation no indication of an alcoholic or
acetic acid fermentation as suggested by Esten and Mason.
It should be emphasized that the assiunption of different
phases of silage fermentation does not mean that the phases 'are
distinctly separated, or that a period of rest occurs when one
phase passes into the next one, or finally that the same phase is
operative throughout the whole quantity of silage. The authors
are inclined to the opinion that conditions of ripening are not the
same in different parts of the silage and that imless samples are
taken from definite regions, if this were possible, the progress of
ripening would appear somewhat obscured. It is suggested
further that the process of ripening may differ in kind and in
degree in different sUos, owmg to Variations in construction, in
moisture content, and to climatic conditions. However, the
fundamental principles and the groups of organisms active in
the fermentation of silage are sunilar under a variety of conditions.
REFERENCES
Babcock, S. M., and Russell, H. L. 1900 Causes operative in the production
of silage. Ann. Rep. Wis. Agri. Exp. Sta., 123-141.
Esten, W. M., and Mason, C. J. 1912 Silage fermentation. Conn. Agri. Exp.
Sta., Bull. 70.
GoRiNi, Conbtantinb 1919 Studi sui silo lattici in base alia fisiologia micro-
bica. Reale istituto Lombardo di sciensae letters, 62, 192-205.
Hbinbman, p. G., and Hefferan, M. 1909 A study of B. btdgairicus. Jour.
Inf. Dis., 6, 304-318.
Httnteb, O. W., and Bushnell, L. D. 1916 The importance of Bacterium hul-
garicum group in ensilage. Science, N.S., 43, 318-320.
Sherman, James M. 1916 A contribution to the bacteriology of silage. Jour.
Bact., 1, 445.
Wtant, Zae Northbup 1920 Experiments in silage inoculation. Abstr.
Bact., 4y 6.
SOME ATYPICAL COLON-AEROGENES FORMS
ISOLATED FROM NATURAL WATERS
MARGARET C. PERRY and W. F. MONFORT
Received for publication July 6, 1920
Attempts to bring cultures isolated from routine water samples
in the laboratory of the Illinois State Water Survey within the
tentative classification of the conmiittee of the American Public
Health Association (1917) reveal certain inadequacies of the
scheme, some of which have been previously noted in the litera-
ture without emphasis.
ANOMALOUS METHYL REI>-V0GES-PR08KAUER REACTIONS
Correlation of the methyl red reaction with the Voges-Pros-
kauer reaction has been adjudged almost complete for low ratio
organisms; but for high ratio types, a very considerable mmober
of exceptions have been noted.
Berrier, McCrady and Lafreniere (1916), applying these tests
to 450 organisms isolated from feces, city sewage and grains,
found the Voges-Proskauer and methyl red tests to agree com-
pletely with the generally accepted standard tests for Bact. coli
organisms when applied to 197 strains from human feces, except
in one instance. Applied to grain and sewage cultures the cor-
relation was found in 80 per cent of the cases.
Levine (1916) cites a small group of organisms isolated from
soil, resembling Boct. aerogenea with respect to gas formation
from various carbohydrates, etc., which did not give the Voges-
Proskauer reaction and were neutral to methyl red after three
days' incubation at body temperature. Some did not give the
Voges-Proskauer reaction and lyere not alkaline to methyl red
imtil the fifth or seventh day of incubation. These resemble
closely a form described by MacConkey, who records the Voges-
Proskauer reaction as positive or negative.
63
54 MABGARET C. PEBRT AND W. F. MONFORT
The strains described by Johnson and Levine (1917) from soil
include four methyl red neutral, Voges-Proskauer positive;
13 methyl red neutral, Voges-Proskauer negative; and 2 methyl
red negative, Voges-Proskauer negative. The temperature and
period of incubation differ from those now current, but con-
cordant results recorded in the same paper are cited by Rogers,
Clark and Lubs (1918) and by Winslow, Kligler and Rothbei^
(1919).
Burton and Rettger (1917) report the biometric method
inapplicable to the colon-aerogenes group on account of the
marked variability of organisms of the high ratio type with
respect to the methyl red test in Clark and Lubs medium (1915)
as well as in others employed. While variability with regard to
the Vogefif-Proskauer reaction was noticeable, it was less frequent
than in the methyl red test. They refer to two cases found by
Rogers, Clark and Davis (1914) and Rogers, Clark and Evans
(1915) where an organism had apparently altered its gas ratio
profoimdly, explained by the authors as possibly due to an error
in lettering apparatus, remarking that this is undoubtedly the
safer explanation, but that in view of the results of themselves
and others in this field variability must also be reckoned with.
In explaining variability of high ratio organisms they suggest
that metabolism may take two courses, not necessarily parallel
or of equal rate : the fermentations may proceed irregularly and
yield equivocal results even when the Witte peptone broth of
Clark and Lubs is used. With the same strain there may be
rapid exhaustion of sugar, heavy growth, large gas volimie,
high gas ratio and low acidity; or incomplete sugar utilization,
small gas volume, low gas ratio, and high acidity. If neither
factor predominates it would be possible to have an organism
capable of giving the Voges-Proskauer reaction and an acid
reaction with methyl red. The authors cite one strain which
became persistently methyl red positive and Voges-Proskauer
positive.
Burton (1916) in his thesis, of which Burton and Rettger pre-
sent the summary, instances 50 strains from sources, mostly
unpolluted, which gave conflicting or variable methyl red and
Voges-Proskauer reactions.
COLON-AEROOENES FORMS FROM NATX7RAL WATERS 55
Miss Bixby (1918) reports 6 strains from waters which are
methyl red and Voges-Proskauer positive; and 1 which is nega-
tive in both reactions.
Levine (1918) included in the aerogenes-cloacae group all
strains which gave the Voges-Proskauer reaction, "practically
always alkaline to methyl red/' and 10 cultures which fermented
starch with gas formation but did not react tjrpically for the
Voges-Proskauer nor the methyl red tests. Of the 151 organ-
isms 142 were from soil, 9 from sewage.
Winslow and Cohen (1918) report perfect correlation between
the methyl red and Voges-Proskauer reactions for 53 strains in a
total of 54 isolated from polluted, unpolluted and stored water.
Winslow, KUgler and Rothberg (1919) speak of their series of
high ratio cultures as including 8 of the Bact cloacae and 23 of
the Bact. aerogenes type, all but 1 alkaline to methyl red and
all but 8 Voges-Proskauer positive.
Rettger and Chen (1919) report an "almost perfect correlation
between the two tjrpes" in the synthetic as well as in the Witte's
peptone medium (not in Difco) when the incubation period was
prolonged to five days. We have seen only the authors' abstract
of this paper.
INTERPRETATION OP ADONITOL REACTIONS
The adonitol positive reaction has been considered discrimina-
tive of Bact. aerogenes of fecal origin, and is so rated in the rather
diagrammatic scheme of the committee of the American Public
Health Association (1917). But Rogers (1918) considers that
while Bact. aerogenes isolated from feces is adonitol positive, it
does not necessarily follow that all waterbome Bact. aerogenes
with this character are therefore derived from immediate fecal
sources.
Rogers, Clark and Lubs (1918) isolated aerogenes strains
from stools of but three out of eighteen persons; all of the 46
strains were adonitol positive ; but of the low ratio cultures from
similar sources 17 were likewise adonitol positive (12.98 per cent).
Darling (1919) cites numerous references in confirmation of
his findings: of 113 coli-like cultures isolated from feces of man
56
MARGABET C. PERRY AND W. F. MONFORT
and of animals none were BacL aerogenes. To his references
may be added Hulton (1916), Stokes (1919) and Rettger and
Chen (1919) who encountered no organisms of the BacL aerogenes
type in 173 cultures isolated from feces.
Far from being a specific reagent for members of the aero-
genes-cloacae group, adonitol probably deserves a place not
much superior to dulcitol as a reagent of rather dubious import
in discriminating members of the low ratio group. Winslow,
Kligler and Rothberg (1919) siunmarize the earlier work of
Kligler (1914) and Levine (1918) in tabular form, to which we
add in parentheses the less usual reactions of these and the high
ratio types:
BacL areogenes
BacL cloacae ,
BacL nea2>olitanii8
BacL cammunior. .
BacL colt
BacL acidi'lactici.
SUCBOSB
BAUCm
DUCITOL
+
+
+-
+
+
+-
+
—
-(+)
+
—
+(-)
—
+
+(-)
*
m
—
ADOHIVOX.
+ -
-(+)
+ (-)
Adonitol is important as being sometimes included in the list of
sugars, etc., fermented by BacL aerogenes, which Winslow and
his co-workers consider as perhaps the most primitive of the
colon-typhoid group, and of the highest fermentative power. As
such it is least significant as an indicator of fecal pollution. The
significance of the so-called ''fecal aerogenes type" in waters is
probably slight.
DEPARTURES FROM STANDARD METHODS
•
Because of the shortage of Witte's peptone and the impossi-
bility of obtaining material for the sjmthetic medium of Clark
and Lubs (1917) for testing the methyl red reaction, Difco pep-
tone was substituted in the initial determinations. Preliminary
tests on pure cultures with 0.75 per cent Difco, properly buffered,
and incubated at SC^C. for two days, gave results identical with
those of the same cultures in the standard Witte broth. As the
nimiber of strains isolated increased, tests w^re repeated with
COLON-AER06ENE8 FORMS FROM NATURAL WATERS 57
newly found cultures, using 0.5 per cent, 0.75 per cent and 1
per cent Dif co in comparison with the standard . methyl red
broth. While the Difco medium, with whatever concentration
used, is not equivalent to the standard broth, the reversion of
acid reaction with definite concentrations of the substituted
peptone with a definite buffer reaction presents phenomena
affording a basis for division of cultures into provisional groups.
From the strains thus segregated some were selected for study
with standard media.
Koser (1918) proposed the use of a medium containing no
nitrogen except in the form of uric acid for the discrimination of
colon and aerogenes forms, reporting the results with 74 strains
of Bact, coll and 50 of BdcU aerogenes: the former showed no
growth; the latter grew well. Rettger and Chen found that,
with few exceptions, among the colon strains from soils the uric
acid test gave very satisfactory correlation with the other 'reac-
tions when necessary precautions were taken. Their culture
comprised 447 strains of the cloacae-aerogenes group and 20 of
the colon type from impolluted soils, and 173 strains from feces
of men and of animals.
To test the validity of this reaction as a criterion of high and
low ratio organisms, we have arranged our cultures isolated from
waters with reference to their uric acid reactions, for later com-
parison with the arrangement of specially studied strains grouped
according to their methyl red and Voges-Proskauer reactions.
STUDY OF CULTURES ISOLATED FROM WATERS .
In the course of this work 392 cultures were isolated which
gave gas in lactose broth, more or less characteristic colonies on
Endo's medium, and usually gas in lactose broth after transfer
from the endo medium. They were tested as to their reaction
in Difco methyl red broths after two days; with adonitol and
with uric acid broth. The first series comprised 233, the second,
159 strains. The results are summarized in table 1. Arranged
according to lactose fermentation, adonitol and uric acid reac-
tions, they fall into 19 provisional groups to which are assigned
reference numbers of purely temporary value.
58
MARGABET C. PERRY AND W. F. MONFORT
The first six groups of strains (uric acid positive adonitol nega-
tive) may be regarded as varying about the third, which is
typical "non-fecal aerogenes." Those grouped under numbers
seven to ten inclusive may be thought of as variants of the so-
called "fecal aerogenes type" (number eight uric acid positive,
adonitol positive). Those grouped under numbers eleven to
TABLE 1
Provisioned arrangement of strains isolated from water
MBTHTL BED
NUMBBB OP
BBPBB-
LAC-
TOSE
BBOTH
ENDO'S
IfBDIUM
LAC-
TOSE
BBOTH
DIFCO
ADONI-
TOL
UBIC
ACID
BPOBE8
8BBIE8
BTBAINS
BxiCK
NUMBBB
G.5
0.76
1
2
TOTAL
percent
percent
1
+
+
—
—
—
—
+
—
16
16
2
+
+
—
+
—
—
+
—
2
2
3
+
+
+
—
—
—
+
—
19
6
25
4
+
+
+
—
—
—
+
t
1
1
5
+
+
+
+
—
—
+
—
4
4
8
6
-h
+
+
+
+
—
+
—
6
3
9
7
+
+
—
—
—
+
+
—
4
4
8
+
+
+
—
—
+
+
—
27
6
33
9
+
+
+
+
—
+
+
—
11
5
16
10
+
+
+
+
+
+
+
—
16
14
30
11
+
+
+
+
+
+
—
—
15
5
20
12
+
+
+
+
—
+
—
—
3
3
13
+
+
+
+
+
—
—
—
84
113
197
14
+
+
+
+
—
—
—
—
5
5
15
+
+
+
+
+
—
—
+
1
1
16
+
+
+
—
—
—
—
■ ^^^
2
2
16a
+
+
+
—
—
—
—
+
1
1
17
+
+
—
+
+
—
—
—
8
2
10
18
+
+
?
+
+
—
—
+
2
2
19
+
+
—
—
—
—
—
7
7
233
159
392
sixteen inclusive (uric acid negative, adonitol positive or nega-
tive) may be variants of number 13 — typical BacL coli.
From numbers 1 to 6 and from 7 to 10 there is progressive
increase in net acidity to the limit of pH 5.8; from 11 to 16 there
is a decrease in acid formation, and from 17 to 19 there is irregu-
larity in acidity and in gas formation in lactose. Five spore-
bearing forms were isolated, which are fully described in a
forthcoming paper.
COLON-AEROGBNES FORMS FROM NATURAL WATERS
59
The second series represents strains which passed through
enrichment processes whenever they showed delayed reaction
with media. Perhaps this may have somewhat diminished the
■
number of forms varying about the three types. In the course
of this treatment the purity of our strains was assured.
There are differences in reactions of strains from a single source
or from one sample of water. Nine of the samples were from
75-foot tubular wells in the same stratimi : two were from a group
of wells furnishing a city supply, and the remaining seven were
from a single nearby well. Table 2 shows the numbers of strains
TABLE 2
Strains isolated from one source
BKrXBSNCa NUIfBER
NVMBKR OF BTBAINB
BBACTZOHB WITH
Urio acid
Adonitol
3
6
8
9
10
11
13
17
19
6
2
9
3
2
7
12
2
1
+
+
+
44
•
assigned to each provisional group. As many as 7 strains, dis-
tributed among 6 groups, were found in a single sample. Of the
44 strains assigned to 9 groups, 22 are uric acid positive; 14 uric
acid positive, adonitol positive; and 14 fall into the transition
groups 5, 9, 10, and 11. Eight vary about "non-fecal," and 14
about "fecal aerogenes;'' 19 about the Bact. coli type, and 3 give
slow lactose fermentation. Other instances of varying strains
from a single sample can be found in table 3.
SPECIAL STUDY OF STRAINS IN TRANSITION GROUPS
Thirty-five strains, mostly from the second series, were tested
with a number of sugaTs, alcohols, etc. (In these tests both a
60
MARGARET C. PERRY AND W. P. MONFORT
TABLES
Reactions of strains in transition groups
BEJPBBKNOK
NUMBBB
4
5a
5b
6a
*6a
6b
9a
9b
9c
9o
9c
10a
10b
10b
10b
10b
10b
10b
ICb
10c
lOd
lOd
lOd
lOd
lOd
11a
lie
lie
lib
lib
15
16a
17
18a
18b
— — — — Raffinose -h
80CIXTT MDMBBB
a
B
<
P IIETBTL BED
•
m
P
-<
O K
0 On
►
+
1
Q
a
o
<
121.1112033
222.1112031
-f
-f
+
—
—
—
222.1132031
.4-
+
—
—
—
—
222.1132031
+
+
—
+
+
—
222.113 031
1
-r
4-
+
—
222.1112031
+
+
—
+
+
—
222.1112031
+
—
+
+
+
+
222.111 031
+
—
—
+
222.1112031
+
+
—
__
-h
+
222.111 031
+
+
+
-f
222.1112031
+
+
+
+
-h
-f
222.1112031
+
+
—
+
—
+
222.1112031
+
+
+
+
—
+
222.1112031
+
+
+
—
+
222.1112031
+
-f
+
+
—
+
222.1112031
+
-f
+
+
—
+
222.1112031
+
-f
var.
+
—
+
222.1112031
+
+
+
+
—
+
222.1112031
+
—
—
—
+
221 . 1112031
+
+
—
+
—
+
222.1112033
+
+
—
+
+
-f
222.1112033
+
+
—
+
+
+
222.1112033
-f
+
—
+
+
+
222.1112033
+
+
—
+
+
+
222.1112033
+
var.
—
—
+
+
222.1112031
—
+
—
—
—
+
222.1112033
—
-f
—
+
+
+
222.1112033
—
+
—
-h
+
+
222.1132031
—
+
—
+
—
+
222.1132031
—
+
—
+
—
+
121.1112011
—
var.
—
—
—
—
121.1113011
—
—
+
—
—
—
222.333 033
—
+
—
—
121.1332032
—
var.
+
—
—
—
. 121.1332033
—
—
+
—
—
—
Bact
Baci
Bact
Bact
Bact
Bact
Bact
Bact
Bact
Bact
Bact
Bact
Bact
Bact
Bact
Bact
Bact
Bact
Bact
Bact
Bact
Bact
Bact
?
?
B. coli ?
B. coli ?
coli
coli
aerogenes
aerogenes
aerogenes ?
communior ?
communior ?
aerogenes
aerogenes 7 Raff.
aerogenes
aerogenes 1
aerogenes
aerogenes
aerogenes
aerogenes
aerogenes 7
aerogenes^
aerogenes
aerogenes
aerogenes
aerogenes
communior 7
communior 7
0.2 per cent and the standard 1 per cent sugar, alcohol and
starch broths were used with identical results.) Some of the
strains were lost before the series of tests was complete. It will
COLON-AEBOOENES FORMS FROM NATURAL WATERS 61
be noted that members of the same provisional group show con-
siderable divergence in their ability to react with sugars, etc.,
and with gelatine. If these variations are made the basis of
subdivision, the nimiber of provisional groups is increased, as
indicated by literal suflSxes to the reference numbers in table 3.
The ctdtures are arranged as before, primarily with regard to
their lactose, uric acid and adonitol reactions, then with
reference to sucrose, dulcitol and glycerol.
For the sake of conciseness the reactions of strams are repre-
sented so far as is possible by the niunerical scheme of the
Society's chart, with the addition of methyl red and Voges-
Proskauer reactions in standard media and a few other reactions.
Maltose and mannitol were fermented with gas formation by all
strains except 17, 18a and 18b. Starch was attacked with gas
formation by but 2 strains, and those were sporeformers. Gela-
tine was liquefied by 10c and by 5 sporeformers. Raffinose and
sucrose reactions were of like signs for all save 5b and 10a.
The inclusion of sporebearing forms in this table is anticipated
by the work of Loehnis and Smith (1916), who state that a single
species (particularly Azotobacter) may pass through as many as
12 to 14 distinct morphological forms in its life cycle, including
spores. Kellermann and Scales (1916), in a preliminary report
on the life cycle of Baci. coliy studied 12 strains from widely
different sources which were found to produce all the types
described by Loehnis and Smith except spores. Burton and
Rettger report 9 occurrences of a form differing chiefly from our
No. 15 in that theirs is Gram positive. Meyer (1918) and
Ewing (1919) isolated from waters a spore-bearing, lactose-fer-
menting, acid-forming bacillus which seems identical with our
16b. Itano and Neill (1919) found sporeformation by B. avbtilis
to be a function of temperature and hydrogen ion concentration :
it is possible that imfavorable environment may lead to spore-
formation by members of the colon-aerogenes group.
Methyl red reactions in different concentrations of Dif co pep-
tone varied upon repetition. The strains grouped under nimi-
bers 4 to 9 inclusive gave slightly more methyl red positive reac-
tions with the 0.5 per cent Witte peptone broth' incubated for 5
62 MARGARET C. PERRY AND W. F. MONFORT
days than with the substituted 0.75 per cent Difco incubated
for 2 days, while with those grouped under reference numbers
10 and 11 agreement between the original reactions in Difco
and in the standard broth was complete. The number of anom-
alies discovered would probably have been even greater had
we been able to use the standard medium throughout this work;
but our purpose of segregating atypical forms was served in a
measure by the provisional grouping based upon the reaction in
Difco peptone broth.
The methyl red reaction was tested after 2 days' and after
five days' incubation in standard Witte broth : but 1 strain (9c)
was acid after two days and alkaline after five days; all the rest
gave concordant results for the two incubation periods at that
time.
Of the 25 uric acid positive strains, two (9a and 9b) are methyl
red negative and have the general characters of BacL aerogenes.
Ten strains give anomalous results with the methyl red and the
Voges-Proskauer reactions : Nos. 4 and 5a fail to ferment salicin,
dulcitol, adonitol, starch and glycerol. The last of the 9c strains
and the first seven of the 10b strains are positive to both methyl
red and the Voges-Proskauer reaction; and the last listed, 10b, is
negative in both these reactions; two of these strains were lost
before salicin tests were made; but the characters of these eight
strains are predominantly those of the aerogenes type.
Thirteen strains are uric acid positive, methyl red positive
with the Voges-Proskauer reaction negative or not recorded:
5b fails to ferment salicin, dulcitol and adonitol and can not be
assigned a place; the two strains 6a resemble Bact. coli in most
^ respects; 6b is sucrose, salicin, dulcitol positive, and is probably
BacL aerogenes; the first two 9c strains resemble BacL cam-
munior; 10a is perhaps more like BacL aerogenes than BacL
communior; 10c liquefies gelatine and ferments all carbohydrates,
etc., save starch and dulcitol: the first four strains numbered
lOd ferment actively all the carbohydrates, etc., except starch
and glycerol; the last lOd fails to ferment salicin, starch and
glycerol. Whether these 13 strains, departing more or less from
type forms, are to be regarded as colon forms from soil or as
COLON-AEROGENES FORMS FROM NATURAL WATERS 63
intermediate between the colon and aerogenes types, their posi-
tive uric acid reaction seems to mark them as without signifi-
cance as indicators of pollution. There is a tendency of strains
grouped under 9 and 10 to approach the maximum of fermenta-
tive power ascribed by Winslow and his co-workers to BacL
aerogenes as the most primitive type of the entire colon-typhoid
group.
Five uric acid negative strains are acid to methyl red and
Voges-Proskauer negative: the two lie strains ferment all car-
bohydrates, etc., tested except starch; 11a resembles BacL com-
munior in that it is salicin and dulcitol negative ; the two strains
marked lib approach BacU coli.
The strains lie and lOd were isolated from apparently unpol-
luted wells, respectively 1300 and 2000 feet deep.
The remaining strains are spore bearers, excepting No. 17,
which lost most of its original characters under laboratory culti-
vation. They resemble the strains 4, 5a and 5b in their failure
to ferment salicin, dulcitol and adonitol.
The relative value of the three criteria for discrimination of
high and low ratio groups with these strains appears from the
following considerations: 15 uric acid positive strains ferment
mannitol, maltose, glucose, lactose, sucrose, salicin, dulcitol
adonitol, and glycerol, or all save one of the last three and are
considered as probable Boot, aerogenes forms; 2 are methyl red
negative; 7 give the Voges-Proskauer reaction, and 1 is variable.
There are 13 discrepancies in the methyl red and uric acid tests,
and 7 or 8 in the uric acid and Voges-Proskauer tests. Two
uric acid positive strains which failed only in fennenting dulcitol
were not tested with salicin: 1 was acid to methyl red and was
Voges-Proskauer positive; 1 was negative in both reactions.
The uric acid test was confirmed by one of these reactions and
negatived by the other in each instance.
Two strains (lib) fermented all the above listed sugars, etc.,
save glycerol, but were uric acid negative, methyl red positive,
Voges-Proskauer negative in repeated tests. These are the only
instances which raise a question as to the validity of the Uric
acid reaction, which in all other cases cited appears preferable
in discriminating high ratio members in waters.
64 MABQABET C. PEBRT AND W. F. MOKFOBT
DISCUSSION OF RESULTS
It is apparent that in our results, as in instances earlier cited,
the methyl red and Voges-Proskauer reactions of the same
strain are not always of opposite signs. Variation in each, but
principally in the former, has been observed in the standard
broth. Ayers and Rupp (1918) have shown that reversion of
acid reaction exhibited by Bact. aerogenes cultures is due to the
secondary decomposition of organic acids and is accompanied by
rapid destruction of formic, acetic and other acids. With Bact.
coli they noted that acid formation does not run parallel with
the destruction of glucose, formic acid remaining constant or
being slightly reduced during the later stages of fermentation.
The distinction between Bact. coli and Bact. aerogenes is con-
sidered as lying chiefly in the difference in rate between the pre-
liminary decomposition of sugars into acids and the secondary
decomposition of the acids themselves. The suggestion was
made by Burton and Rettger that there may be a difference in
the rate of the secondary decomposition even in strains of Bact.
aerogenes which would explain divergence in the atypical strains
such as we are considering. They found the Voges-Proskauer
reaction more reliable than the methyl red reaction, as cited
above. The simpler uric acid reaction may prove even more
dependable than the complex Voges-Proskauer reaction, being
accomplished in briefer period and permitting less modification
of the strain under cultivation. It is true that Rettger and
Chen found it possible to shorten the incubation period from
five days to twenty-four hours (even ten to fourteen hoiurs) with-
out altering the Voges-Proskauer reaction; they also report the
successful use of Difco peptone in this test. But even with this
reduction in the time element the possibility of variation in the
complex reaction is not removed.
The positive uric acid reaction overlaps the acid methyl red
and the negative Voges-Proskauer reactions in many strains.
If the observation is confijmed, that the Koser reaction gives
satisfactory correlation with the other reactions except among
colon strains from soils, this may prove of value in clearing up
OOLON-AEROGENES FORMS FROM NATURAL WATERS 65
ft
such anomalies as have been emphasized in this work and men-
tioned in the earlier cited references.
A considerable nimdber of methyl red positive strains gave
deferred fermentation of lactose (after three. days) which is
in Ime with the observations of Bronfenbrenner and Davis
(1918) on BacL coli from foods. Similar behavior of colon forms
in gentian violet broth has been ascribed by Hall and EUefsen
(1919) to the inhibitive effect of the dye: it may have been in
part attributable to the inhibitory effect of lactose itself , noted
by Smith (1893), confirmed by Burling and Levine (1916), and
recognized in the latest reconmiendation of the committee of the
American Public Health Association (1920), which reduces the
percentage of lactose in broth to 0.5 per cent. If our observa-
tion holds, that 0.2 per cent of lactose and other sugars and
alcohols suffices in culture broths, some relief might be expected
from delayed development of gas; but our strains reacted simi-
larly in both 1 per cent and 0.2 per cent sugar broths throughout.
In the most striking instances of erratic behavior studied there
was no marked difference in the time of beginning gas production
by typical and atypical forms.
The list of anomalous strains is undoubtedly incomplete:
Levine, Burton and Rettger, and Burton in his thesis, to which
we have had access through the courtesy of the author, Bron-
fenbrenner and Davis, and Rettger and Chen suggest abundant
material not yet reducible to the fixed categories of any classi-
fication. This may be said also of the sporebearing forms;
although some of them can hardly be' confused with typical
BacL coli, several are likely to lead to misapprehension as to the
safety of a water supply.
INTERPRETATION OF LABORATORY RESULTS
If the atypical strains, sporebearers and vegetative forms
herein listed and cited, are considered as intermediate or transi-
tion forms from accepted colon or aerogenes types, the question
of sanitary interpretation in unavoidable. Any of the lactose
fermenting organisms (29 of the 31 especially studied) would
lead to the condemnation of a water supply according to the
JOUUIAL or BACrXBIOLOOT, VOL. VX, NO. 1
66 MARGARET C. PERRY AND W. F. MONFORT
United States Treasury Department (1914) standard if more
than two organisms were found in 100 cc; of these 29, 3 are
sporebearers, 1 is typical BacL aerogenea not necessarily of fecal
origin (Rogers 1918) , 9 are anomalous with respect to those
reactions accepted as indicative of high and low gas ratio; 16 are
within the class of low ratio organisms on the basis of the methyl
red and Voges-Proskauer reactions, and of these but 3 uric acid
negative strams conform to recognized types.
An organism which requires prolonged invigoration to be
restored to, or to acquire, conventional reactions with sugar
broths and other media is far removed from the organism typical
of fecal pollution. Considering the opportunity thus afforded
for change in the original characters, a conclusion as to what
must be regarded as essential indicators of pollution must take
into account the undoubtedly wide variation of bacilli of the
general colon-aerogenes group occurring in waters. Invigora-
tion might lead an organism, long away from, or originating
quite outside, the alimentary tract, to acquire the characters of
typical fecal inhabitants. While it is important to ascertain the
ultimate genetic relation between members of the group, it is one
thing to say that these forms are of common, remote origin, and
a very di£ferent one to say that the existent, feebly reacting, yet
convertible forms are identical with, and of equal diagnostic
importance with, organisms freshly isolated from feces under
laboratory conditions: that is, to attribute' to them as originally
present in a water supply all the newly acquired characters.
The uric acid reaction, however, admits of repetition without
change so far as we have found with the limited nmnber of strains
isolated.
. It is important that the laboratory procedure be as quickly
(i)mpleted as is reasonably possible, and that characters be
neither lost nor acquired. Water seriously polluted shows gas
production within much less than 24 hours. The readiness of
strains to react is perhaps of greater diagnostic significance than
the appearance of gas at twenty-four hours and at forty-eight
^ hours as now observed. Levine (1920) considers the rate of
gas production more significant than the total volume of gas
formed. Biu*ton suggested shortening preliminary enrichment
Jl
COLON-ABKOGBNBS FORMS PROM NATURAL WATERS 67
to avoid development of Bact. cloacae. The committee's recom-
mendation (1912) for enrichment with transfer ''as soon as gas
is formed (usually in sixteen to twenty-four hours)" has persisted
in many laboratories and is perhaps worth reviving officially,
not so much to avoid overgrowth as to prevent undue modifica-
tion. For the same reason the Voges-Proskauer reaction tested
at the end of ten to fourteen hours' incubation in available
American peptone broth is preferable to reliance upon the methyl
red reaction, which requires 5-day incubation in a broth for
which materials are not generally at hand. The uric acid test
seems worthy of at least provisional acceptance because of the
simplicity of the reaction and the facility afforded for confirming
or correcting the somewhat erratic results observed in the Voges-
Proskauer reactions of soil and water borne strains.
SUMMARY
Strains isolated from natural waters are grouped by their lac-
tose, uric acid, adonitol, and methyl red reactions in Difco pep-
tone broth (0.5 per cent and 0.75 per cent), and 35 strains espe-
cially studied are so arranged as to niake evident the conflict
between the Voges-Proskauer reaction and the methyl red reac-
tion of strains in standard Witte peptone broth. There is lack
of agreement in the discrimination of high and low ratio types.
The uric acid positive reaction correlates best with the char-
acters of the aerogenes type in carbohydrates, etc.
Upon the assmnption that the uric acid reaction of colon forms
from soils sufficiently characterizes them, this reaction may
prove useful in checking and correcting the assignment of strains
to the low ratio type indicative of possible fecal polk!i;ion.
Five sporebearers were isolated. It is probable that the
niunber of these and of other anomalous forms is far less than
would have been discovered had we been able to use Witte pep-
tone in all methyl red tests.
The sugar reactions of members of the larger group seem to be
as well tested in 0.2 per cent sugars as in the 1 per cent broths
of the old standard procedure.
For the purpose of sanitary e^^amination of waters it is desir-
able that the laboratory procedure be completed as early as con-
68 MARGARET C. PERRY AND W. F. MONFORT
sistent with fairness to avoid change in characters, and to this
end those methods are preferable which involve the sunpiest
reactions and the bridfest incubation periods.
REFERENCES
American Public Health Association 1912 Standard methods for the exami-
nation of water and sewage
American Public Health Association 1917 Standard methods for the exami-
nation of water and sewage.
American Public Health Association 1920 Standard methods for the exami-
nation of water and sewage.
Atsbs, S. H., and Rupp, P. 1918 Jour. Inf. Dis., 23, 188.
Bkbbieb, McCbadt and Lafbeniebe 1916 Bull. San., Quebec, 16, 93.
BiXBT, Madbunb 1918 Bull. 111. State Water Survey, 16, 100.
Bbonfenbbbnneb, J., AND Davis, C. R. 1918 Jour. Med. Res., 39, 83.
BuBUNo, H. A., AND Lbyine, M. 1918 Amer. Jour. Pub. Health, 8, 306.
BuBTON, L. V. 1916 (Thesis) Correlation studies of gas-producing bacteria,
with special reference to members of the colon-aerogenes group found
in soils.
BuBTON, L. v., AND Rettgeb, L. F. 1917 Jour. Inf. Dis., 21, 162.
Chbn, C. C, and Rettoeb, L. F. 1920 Jour. Bact., 6, 253.
Clabk, W. M., and Lubs, H. A. 1915 Jour. Inf. Dis., 17, 160.
CiiABK, W. M., AND Lubb, H. A. 1917 Jour. Biol. Chem., 30, 209.
Dablino, C. a. 1919 . Amer. Jour. Pub. Health, 9, 844.
EwiNG, C. L. 1919 Amer. Jour. Pub. Health, 9, 257.
Hall, I. C, and Ellbfsbn, L. J. 1919 Jour. Amer. Water Works Assoc, 6, 67.
HuLTON, Flobbnce 1916 Jour. Inf. Dis., 19, 606.
Itano, a., and Nbill, J. 1919 Abst. Bact., 3, 2.
JoHNBON, B. R., AND Leyine, M. 1917 Jour. Bact., 2, 379.
Kbllebmann, K. F., and Scales, F. M. 1916 Abst. Bact., 1, 27.
KuGLBB, I. J. 1914 Jour. Inf. Dis., 16, 187.
KosEB, S. A. 1918 Jour. Inf. Dis., 23, 377.
Leyine, M. 1916 Jour. Bact., 1, 619.
Levine, M. 1918 Jour. Bact., 8, 253.
Leyine, M. 1920 Jour. Amer. Water Works Assoc., 7, 188.
Loehnis, F., and Smith, N. R. 1916 Jour. Agr. Res., 6, 675.
Meteb, E. M. 1918 Jour. Bact., 8, 9.
Rettoeb, L. F., and Chen, C. C. 1919 Abst. Bact., 3, 1.
RooBBs, L. A. 1918 Jour. Bact., 3, 313.
RooBBS, L. A., Clabk, W. M., and Dayis, B. J. 1914 Jour. Inf. Dis., 14, 411.
RoGBBS, L. A., Clabk, W. M., and Eyanb, A. C. 1915 Jour. Inf. Dis., 17, 137.
RoGEBS, L. A., Clabk, W. M., and Lxtbs, H. A. 1918 Jour. Bact., 3, 23.
Smith, T. 1893 The Wilder Quarter Century Book, 187.
Stokes, W. R. 1919 Amer. Jour. Pub. Health, 9, 571.
United States Tbeabitbt Depabtment. 1914 Pub. Health Repts., 29, 2960.
WiNBLOW, C.-E. A., AND CoHEN, B. 1918 Jour. Inf. Dis., 23, 82.
WiNBLow, C.-E. A., KuoLEB, I. J., AND RoTHBEBG, W. 1919 Jour. Bact., 4,^9.
BOTULISM IN CATTLE
ROBERT GRAHAM and HERMAN R. SCHWARZE
Department of Animal Husbandry , Laboratory of Animal Pathology , University
of Illinoia
Received for publication July 11, 1920
The etiologic factor, or factors, in a sporadic toxemic-like
disease .in cattle sometimes designated as forage poisoning have
been the subject of many experimental studies in the last decade.
During this time the disease has occurred sporadically with
varying severity throughout the middle western states, and
more recently our attention has been repeatedly invited to
these losses. It may be significant to mention that com silage
of some character was being fed to many of the herds develop-
ing the disease that came under our observation during the
winter months of 1919-1920, yet this feed was definitely incrim-
inated in but three instances. The primary relation of B. botu-
linus-hke organisms to one type of forage poisoning in horses
and mules, together with the occasional occurrence of this
anaerobe in different animal feeds, has suggested the importance
of determining the relation, if any, of certain toxic anaerobes
to so-called forage poisoning in cattle, and our investigations of
the disease in these animals have been devoted primarily to the
pathogenic and toxic characters of spore bearing anaerobes in
suspicious feeds, and of like organisms encoimtered in the intes-
tinal content and spleen of animals fatally afflicted.
CLINICAL SYMPTOMS
In view of the fact that so-called forage poisoning in cattle
may apparently be confused with hemorrhagic septicemia or
enteric bacterial infections of the colon-typhoid group, or other
rapidly fatal diseases of a toxemic character, a brief description
69
70 ROBERT GRAHAM AND HERMAN R. SCHWARZE
of the symptomatology of the disease mider mvestigation is
given. A differential diagnosis based upon clinical symptoms
and gross anatomical findings at death may perplex the clinician
and autopsist in many outbreaks. As noted to date in several
affected animals, an acute and chronic symptom-complex of food
or forage poisoning may be recognized in cattle. In the latter,
weakness, local paresis, emaciation, muscular stiffness and
decumbency are noted in varying degrees. Clonism develop-
ing without premonitory symptoms, terminating in sudden
death, or followed by complete relaxation and recovery, marks
the acute form of the disease. The nervous manifestations may
be of a vicious character resulting in violence to feeding troughs,
mangers or fences. Noticeable symptoms are not observed in
the peracute disease preceding the agonal clonic spasm. Ani-
mals may remain decumbent for two or more days before death,
during which tune dyspnea, opisthotonus, coryza, lacrymation
and catarrhal conjunctivitis often develop. One fatal spon-
taneous case delivered to our laboratory suffered from a second-
ary bronchial pneumonia, disclosed at autopsy. Several unsue-
cessful attempts to administer medicine by the mouth to the
animal before death were probably associated with the develop-
ment of the pneumonia, which was clearly of medicinal or
mechanical origin.
In the more chronic cases animals may display visual dis-
turbances. An estranged or frightened attitude on being
approached, or a staring expression of the eyes, is noted. Ema-
ciation and weaknesis contribute to an ill nourished cachectic
appearance. Contraction of the flexor tendons in the posterior
limbs, resulting in an extension of the metatarsalphalangeal
articulation ("cock ankle")? with incoordination of movement, is
not an imcommon complication, and animals may appear stiff,
with a noticeable nervous attitude, and even loss of control in
the anterior limbs, on being suddenly approached. Restraint
or excitement of animals suffering from the chronic disease,
accompanied by running or violent exertion, may terminate
fatally from cardiac failure. In the acute type of bovine botu-
lism partial or complete pharyngeal paresis. is not uncommon,
BOTULISM IN CATTLE 71
yet in the chronic disease the appetite as well as organs of deglu-
tition appear quite normal. The body temperature remains
essentially unchanged; with slight fluctuations upward which
are of short duration unless associated with secondary infection.
Subnormal temperature and obstinate constipation are invari-
ably present.
SUSCEPTIBILITY
Preliminary observations indicate that cattle between the
ages of six months and two years are most susceptible, while
older animals may also be affected. The mortality varies
between 2 and 10 per cent though in extreme outbreaks a loss of
30 to 70 per cent or higher may occur. From observations it
would appear that some cattle have, or acquire, an immimity
to certain types of poisonous substances in feed, yet the natural
resistance possessed by cattle of aU ages to the type of intoxica-
tion under consideration is not always sufficient to protect
against more or less serious constitutional disturbances. In
more resistant animals death is not induced, yet the growth
and development of the affected animal may be temporarily or
permanently impaired. The mortality of the disease in many
outbreaks may thus be secondary to the loss sustained by failure
of the animals to increase in weight, by the decrease in milk
flow in dairy cattle, or the loss of the feed in case the contami-
nated ration can be detected. Moreover it is believed that
symptoms of B. hotulinus intoxication in resistant cattle may
thus be transitory and of an mdefinite character, and that bovine
forage poisoning may even prevail unrecognized as a distinct
disease, manifested only by unthrift and malnutrition. In the
light of recent observations the writers have probably failed to
recognize the disease in cattle as a clinical entity in several out-
breaks during the period of 1912-1917.
CAUSATIVE FACTOR RELATED TO RATIONS
In clinical outbreaks of the above character, bacteriological
evidence has seldom been obtained to sustain or refute a pre-
simiptive diagnosis of a food or forage poisoning. As a matter
72 ROBERT GRAHAM AND HERMAN R. SCHWARZE
of fact the cause of the disease as it occurs throughout the Mis-
sissippi Valley has been satisfactorily established in but few
outbreaks. Notwithstanding negative findings relative to the
cause or causes involved, the recurrence of a clinical toxemic-like
disease in cattle in the feed lots and pastures of Illinois and
other middle western states lends evidence to the possibility of a
distinct entity of forage poisonmg, based upon our clinical con-
ception of food poisoning in other domestic animals, i.e., in
horses and mules (Graham, Brueckner and Pontius (1917) ). In
these animals the cause of death in several sporadic outbreaks
has apparently been definitely associated with certain types of B.
botvliniLS intoxication, as demonstrated by bacteriological find-
ings in the feed and confirmed by the apparent protective value
of specific antitoxin in susceptible animals receiving contami-
nated rations.
Feeding experiments (Rusk and Grindley (1918)) have been
conducted by different investigators in an attempt to reproduce
the disease in cattle. An accomplishment of this character would
obviously afford an qportunity to inaugurate more definite
and extended bacteriological studies, looking to the establish-
ment of an etiologic factor. Experimental results in cattle
feeding projects, together with the natural resistance of some
animals accompanied by the abrupt or irregular termination of
the spontaneous fatal disease in natural outbreaks, have in a
broad sense failed to incriminate the rations specifically. How-
ever, in many outbreaks it appeared that the causative factor or
factors were related to, if not incorporated in the feed. With
this conception of the etiological relation of the feed to the
disease, bacteriological studies have been extended to numerous
sampJes of feed from suspicious outbreaks of this disease. The
possibility of the disease or diseases encountered being associated
with Pdsteurella bovisepticay or toxic aerobes of the colon-typhoid
group prompted animal inoculation and cultural methods to
eliminate these microorganisms in tissue specimens.
Moulds have been mentioned in a more or less definite way in
connection with forage poisoning in cattle and horses. A variety
of these organisms have been encountered upon animal feeds
BOTULISM IN CATTLE 73
and it is suggested that these organisms may apparently be
associated with the disease or may serve as causal agents in a
secondary etiologic capacity, since experimental evidence in
animals, to demonstrate the primary toxic character of certain
organisms of this class per se, is unconvincing. If deductions
are to be drawn at this time from a review of the literature and
experimental evidence at hand in our studies, it appears that the
moulds encountered are probably not of widei^pread primary
importance in the toxemic-like disease of animals in question,
as it occurs throughout the Mississippi Valley.
The writers have observed outbreaks of so-called forage
poisoning in equines which were quite definitely related to the
consumption of feed containing B. botulinus toxin. Susceptible
animals (horses and mules) could be protected against the toxin
in the feed by a prophylactic injection of botulinus antitoxin
(Graham and Brueckner (1919) ). The relation of B. botuliniLs of
human origin (type B), was also noted by immunologic tests,
while Burke of California has more recently incriminated B.
botulinics (type A) in forage poisoning in horses (Burke, 1919).
This strain has not been encountered to date in outbreaks of
equine botulism coining under our observation.
RESISTANCE OF BOVINES TO BOTULINUS TOXIN
Following preliminary field observations of bovine forage
poisoning in Illinois, Rusk and Grindley state
The results of these investigations seem to indicate that most cattle
are not so susceptible to forage poisoning as are horses and mules, and
that contaminated com silage, and possibly other animal feeds which
are unsafe or fatal to horses, may be fed with less danger to cattle
. . . . however, the evidence from many outbreaks leads the
authors to suspect that some cattle are more susceptible than others
and that damaged or otherwise contaminated corn silage, or possibly
other feeds, may in some instances produce fatal results in cattle fol-
lowing ingestion.
Cattle have been fed rations spontaneously contaminated -with
lx)tulinus toxin (type B) without manifest symptoms of illness
other than loss of body weight, and mature cattle have con-
74 ROBERT GRAHAM AND HERMAN R. SCHWARZE
sumed ten to twenty lethal equine doses of botulinus toxin
(type B) at one time in wholesome feed without inducing notice-
able symptoms. In fact our observations indicate that a mature
ruminant may possess marked resistance to botulinus toxin
(type B) in the feed.
Information relative to B. bottdinus-like organisms and their
relation to forage poisoning in cattle, if any, has been eagerly
sought in natural outbreaks, yet the degree of tolerance experi-
mentally observed in mature, healthy experimental cattle to
botulinus toxin (type B) suggested the possibility of an inde-
pendent factor in this disease of bovines, and until recently the
spontaneous occurrence of forage poisoning in cattle, wherein
the rations proved to be contaminated with B. botuliniis-like
organisms, was in our observations without convincing bacterio-
logical and immunological evidence.
SILAGE CONTAMINATED WITH B. BOTULINUS
In January, 1920, a sample of silage (Laboratory index 126),
was received from Mr. L. W. Wise of Iroquois County, Illinois.
It was stated that the sample in question was representative of
feed which had apparently proven injurious to a herd of forty-
seven pure bred cattle of all ages. Upon physical examination
the silage did not show noticeable indications of spoilage. There
were scant circumscribed colonies of wild yeast {Monilia Can-
dida Bon) on some of the leaves, which was identified in pure
cultures by Professor H. W. Anderson, Assistant Professor of
Pomology, University of IlUnois. The colonies of yeast were
visible only on close examination and the specimen could not be
regarded as mouldy in the general sense that some feeds harbor
organisms of this class. Indefinite evidence which pointed to
the disease producing properties of the silage consisted of symp-
toms of illness observed in several (18) cattle, and as described
by the owner, included inappetance, marked emaciation, con-
stipation and general unthrift, with some transitory nervous
manifestations (see fig. 1). Four animals chronically affected
died. The younger animals of the herd were apparently not as
susceptible as the mature full grown animals, or it may be pre-
BOTUIJSM IN CATTLE
76 ROBERT GRAHAM AND HERMAN R. SCHWARZE
sumed that the older animals consumed more of the silage.
The owner noted that trough space prevented the small animals
from getting as liberal a portion of the feed as the older animals
secured. Simultaneously with the marked illness and death of
the animals, feeding of silage was discontinued and the herd
improved. After an interval of three weeks the cattle were
again allowed to eat of the silage in small quantities and illness
again appeared in some animals of the herd. The S3nmptoms
were analagous to the manifestations noted in the original out-
break, but the silage was promptly elimin&ted from the daily
ration and the affected animals improved and made a complete
recovery. This experience suggested to the owner that the
silage could not be safely used for feeding purposes, and oppor-
tunity to observe the effect of the continuous feeding of the silage
in this herd or to other cattle or horses was not provided.
The clinical illness in these cattle on two separate occasions
was at marked variance with experiments in feeding rations
spontaneously contaminated with botulinus toxin to horses and
mules, in that the character of the disease in cattle was chronic
and slowly fatal. Furthermore, the manifest symptoms reported
in this herd had not been noted in feeding B. botulinus contami-
nated silage to cattle, yet the anamnesis appeared somewhat in
keeping with other spontaneous outbreaks of a disease of unknown
etiology occurring in cattle throughout the corn belt states.
While clinical deductions might have suggested the presence
of a poisonous substance in the silage, there appeared two impor-
tant possibilities for consideration in this assumption, (a)
The poisonous substance in the silage was not overcome by the
natural resistance of the animals, or (b) the illness was induced
by bacterial agents, chemicals, et cetera, unassociated with the
silage and not mentioned by the owner. No feeding experi-
ments were conducted to incriminate the silage further, but a
bacteriologic examination of this feed was made.
BACTERIOLOGICAL FINDINGS
A sample of silage (50 grams) received for examination was
immersed in sterile water and allowed to macerate in a dark
place twenty-four hours at a temperature of 22°C. The sample
BOTULISM IN CATTLE
77
was then gently shaken and the liquid content removed to a
sterile flavsk. Small particles of visible silage were removed by
filtering through four layers of sterile gauze. The filtrate was
then seeded in shake agar culture and heated fifteen minutes to
80°C. to destroy vegetative bacteria. The inoculated tubes
were quickly placed in a cold water bath and allowed to solidify.
On the surface of the agar to a depth of 2 to 6 cm., equal parts
of agar and glycerol containing 1 per cent phenol were added to
insure anaerobiosis. Ten days later the cultures, after incubat-
ing at 22°C., were examined and in one of the fifteen dilutions
planted there was gas formation in the base of the tube, though
distinct colonies were not visible. Anaerobes encountered in
animal feeds, in our observations, are favored by the addition of
glucose to the media, yet the numerous saprophytes encountered
may outgrow and even disguise the presence of B. botulinvs-
Uke organisms. It is true that B. botulinus does not thrive on
agar, yet it seems to develop slowly in plain agar shake cultures
at 22''C. to 25°C. with limited gas production. Subculturing in
glucose pork agar and transferring colonies to glucose pork broth
(faintly alkaline) was employed to determine the toxic character
of anaerobes cultivated in agar after ten days incubation in
vacuum or hydrogen atmosphere. The normal toxicity of
newly isolated B. botuliniLS'\ike organisms in broth cultures may
not be characteristic or fully acquired until the second or third
transfer at intervals of seven to ten days. The cultural char-
acters and toxic quality of B. botulinus from silage as observed
in guinea pigs, is illustrated in table 1; and in figures 2 and 3.
All animals succumbed with the symptoms characteristic of
B, botulinus intoxication.
TABLE
1
KCTMBRK
WEIGHT
DATB
TOXIN 126
RESULT
1
250
1/20/20
0.1 per 08
Died 1/22/20
2
250
1/20/20
0.1 per OS
Died 1/23/20
3
250
1/20/20
0.1 per 08
Died 1/22/20
4
250
1/20/20
0.1 per OS
Died 1/21/20
5
250
1/20/20
0.1 per OS
Died 1/21/20
6
250
1/20/20
0.1 per 08
Died 1/21/20
7
250
1/20/20
0.1 per 08
Died 1/21/20
' B. BOTULINUS IliOLATSD FROU
80 ROBERT GRAHAM AND HERMAN R. SCHWARZB
IMMUNOLOGICAL FINDINGS
Imiiiuiiologieal tests upon guinea-pigs using unfiltered broth
cultures of the toxic ana!erobe isolated from com silage (12G)
and botulinus antitoxin prepared from a heterologous strain of
B. botulinus, gave evidence of the identity of the toxin and
according to Burke's classification (1919) proved to be of type B
variety. The strain possesses the usual pathogenic characters
for small laboratory animals and is culturally analagous to
; Tebt Showino Relation op Strain op Toxin prom
Silage No. 126. B. botolinus Antitoxin (Type B)
Tlic Ihree pigs in the rear received the serum and toxin. The control pig
received the toxin only.
other strains of B. botulinus. Botulinus antitoxin {type B)
proved efficacious in small animals against many lethal doses
(c. f. 100) of toxin per o"s. An arbitrary toxic unit of 0.001 cc,
which represents the minimum lethal dose, when given per os to
guinea pigs of a given weight, has been tentatively used in deter-
mining the relative potency of antitoxic serum. This toxic
unit per os in guinea-pigs weighing 250 grams may produce
symptoms in twenty-four to forty-eight hours and is invariably
BOTULISM IN CATTLE
81
followed by death on the ninth or tenth day. Results of munun-
ologic tests in guinea-pigs as in table 2 illustrate the specific
relation of the B. botttUnus strain from the com silage sample
126 to type B variety (see fig. 4) . One to two cubic centimeters
of antitoxic serum of the desired potency has repeatedly proven
efficacious against 100 minimum lethal toxic units given sepa-
rately by the mouth at the time or a' few hoiurs after the anti-
TABLE2
KUMBBB
WBiosr
OATB
SBBUM TTPB B
TOXIN 126
BBBULT
1
2
3
4
780
785
800
775
1/21/20
1/21/20
1/21/20
1/21/20
2 cc. subcutaneously
2 cc. subcutaneously
2 cc. subcutaneously
0
0.1 per OS
0.1 per OS
0.1 per OS
0.1 per OB
Heahhy
Healthy
Healthy
Died 1/23/20
serum, while 0.001 cc. of antitoxin of sufficient strength per
gram weight suffices to protect a guinea-pig against 100 mini-
mum lethal doses of toxin given by the mouth. Guinea-pigs
varying in weight from 200 to 800 grams, owing to shortage of
pigs of uniform weight, have been employed to note the specific
relations of the toxin to the antitoxin of types A and B. In
table 2 the relation of strain 126 to tjrpe B immune serum is
tabulated.
SERUM TREATMENT OF CATTLE
•
The preliminary bacteriologic and immunologic studies herein
enumerated suggested that the losses in cattle consuming the
silage was probably associated with B. hotvlinuB intoxication.
This conclusion was practically established in the laboratory
when it was learned that several tons of the silage in question
were to be condemned and discarded as unfit for feeding jpur-
poses. In view of the preliminary findings the advisability of
recommending that this silage be fed to the cattle seemed logical
to us, providing the animals in the herd might first be injected
with botulinus antitoxin. It was believed that the practical
value of specific antitoxic serum in cattle for the prevention of
botulism might be observed and possibly definitely demon-
82 ROBERT GRAHAM AND HERMAN R. SCHWARZE
strated under natural conditions comparable to field tests with
horses (Rusk and Grindley) wherein the value of antitoxin was
apparently observed.
Dr. I. B. Boughton of the Animal Pathology Division, Uni-
versity of Illinois, with the consent of the owner treated 43
cattle of the original herd with antitoxin, type B. Amoimts
varying from 30 to 50 cc. were injected subcutaneously into
each animal. A control or untreated animal was placed in the
herd with the 43 treated cattle. Following the injection of
serum the silage which had previously proven injurious to cattle,
and which upon examination proved to be contaminated with
B. hotvlinus (type B) was fed in liberal amounts for sixty con-
secutive days, until the supply of silage was exhausted. No
symptoms of illness were noted in the treated animals and the
one untreated animal.
The protective value of type B serum in these animals must
be discounted, in the opinion of the writers, for the reason that
a degree of immunity might have been developed by a previous
illness which had occurred in approximately one-half of the
animals of this herd and which in all probability was induced by
botulinus toxin in the silc^e. The control animal did not suc-
cumb or even display clinical symptoms of illness, and therefore
no precise and definite deductions can be drawn, yet the pro-
tective value of botulinus antitoxin in laboratory tests suggests
the possible value of this antitoxin in combating B. botulinus
intoxication in cattle, as well as the advisability of further tests
of this character in the control of natural outbreaks of this
disease in bovines.*
^ As this manuscript is being prepared the importance of a polyvalent serum
in further trials is suggested by the results of bacteriologic and immunologic
findings in two separate and distinct outbreaks of botulism in cattle occurring
near Paxton, Illinois, wherein A and B types of B. botulinus respectively were
encountered.
During the feeding test, the owner advised that the silage in question had
been fed independently to an untreated cow not included in the experimental
group, with the result that the animal developed symptoms indistinguishable
from the illness originally observed in the herd. This animal had not previ-
ously received the silage and the owner's observations seem worthy of record.
BOTULISM IN CATTLE 83
SUMMARY
1. An anaerobic bacillus biologically resembling B. botulimis
(type B) was isolated from a com silage (126).
2. Several (18) cattle of the herd consuming the silage in
question developed symptoms of forage poisoning on two dif-
ferent occasions and four animals died. It is possible that
botulinus toxin in the ensilage was primarily related to the
disease in question.
3. The silage was regarded as unsafe for cattle and after dis-
continuing its use in the daily rations, the animals remained
healthy.
4. Botulinus antitoxin (type B) proved efficacious in pro-
tecting guinea-pigs against lethal doses of toxin in unfiltered
broth cultures produced by the anaerobic bacillus isolated from
the com silage (126).
5. An opportunity was afforded to inject forty-three cattle
on this farm with botulinus antitoxin, and subsequently to feed
them with the silage. The animals remained apparently healthy.
One control or untreated animal did not show visible illness and
the vahie of the antitoxin in the feeding operations is therefore
not conclusive. It is worthy of record that the treatment did
not injure the animals and encourc^ement is offered for more
extensive field trials in determining the value of the antitoxin in
cattle against the ill effects of otherwise nourishing rations
containing B. botulinus toxin which heretofore has advisedly
been discarded. The latter item is of importance considering
the increased cost of producing grain and forage.
REFERENCES
BiTBKS, G. 8. 1919 Notes on Bacilltu hottdimu. Jour. Bact., 4, 555.
1919 The occurrence of BaciUus hotulinu9 in nature. Jour. Bact.,
4,541.
Gbaham, Robebt, Bbubcknbb, a. L., and Pontius, R. L. 1917 Studies in
forage poisoning, V and VI. BuUetin 207-206, Kentucky Agricultural
Experiment Station.
Gbaham, Robebt, and Bbxtecxneb, a. L. 1919 Studies in forage poisoning.
Jour. Bact., 4, 1.
Rusk, H. P., and Gbindlet, H. S. 1918 Field investigations of forage
poisoning in cattle and horses. Bulletin 210, Illinois Agricultural
Experiment Station.
NOTE ON THE INDOL TEST IN TRYPTOPHANE
SOLUTION
GHR. BARTHEL
Department of Bacteriology, Central Agricultural Experiment Station, Bxperi-
mentalfdUet, Stockholm
Received for publication, July 22, 1920
The application of the indol test to tryptophane solutions by
H. Zipfel was, without doubt a great advance. The theoretical
basis of this reaction is so generally^ known that it is superfluous
to give an explanation here.
In applying the method of Zipfel it has happened on different
occasions, that I have failed to obtain growth (turbidity) in the
tryptophane solution even with bacteria, which are known as
strong indol liberators,' as for example Bad. vulgare. Of course
in this case there is also no indol reaction with the reagent of
Ehrlich (p-dimethylamidobenzaldehyde). It occured to me that
this failure might be due to the hydrogen ion concentration in
the solution in question.
Zipfel says nothing about the neutralization of the solution
in either of his two publications on this subject and so far as I
know, this fact has never been pointed out by any other worker.
In an electrical determination of the hydrogen ion concentration,
which I undertook on a tryptophane solution of the composition
prescribed by Zipfel* I found the value of the pH = 5.41.
^ Centralbl. fur Bakteriol., Abt. I., Orig., 64, 1912, 65; Centralbl. fUr Bakteriol.
Abt. I., Orig., 67, 1913, 672.
* The term "liberation" is better than "formation," as the action is merely
a splitting up of the trjrptophane molecule, with liberation of the indol group.
s
perc*nt
Aspairagin 0.6
Ammonium lactate 0.5
Potassium diphosphate 0.2
Magnesium sulfate 0.02
Trsrptophane 0.03
85
86
CHR. BARTHEL
As is obvious, this is a manifestly acid solution. The possi-
bility that here was the explanation of the failure to obtain
growth with BacL vulgare now seemed very probable to me.
An investigation of this question was therefore undertaken,
which I wish to present in this paper. I have also attempted
to answer another question, namely, whether or not it is neces-
sary to have both asparagine and ammonium lactate present in
the solution.
The researches, after a series of orientation experiments, which
need not to be given here, were carried out in the following
manner: 500 cc. of the tryptophane solution, but without
TABLE 1
pH
COMPOSITION or THE SOLITTION
Before
steriliiatton
After
steriluBtaon
With ftmmoniun^ lactate, nftiitr&l
6.81
5.21
6.81
4.86
6.29
With ammonium lactate, neutral. Jena glass
With ammonium lactate, acid
6.97
4.83
With ammonium lactate, acid. Jena slass
4.69
Without ammonium lactate, neutral
6.23
Without ammonium lactate, neutral, Jena glass
Without ammonium lactate, acid
6.03
4.83
Without ammonium lactate, acid, Jena slass
4.67
ammonium lactate, was divided into two portions of 250 cc.
each. To one of these was added 1.25 grams (0.5 per cent)
ammonium lactate. Each one of these solutions was divided
into two parts, of which one was left as it was, while the other
was neutralized with n NaOH to litmus. All of these four
solutions were then transferred to test tubes (10 cc. per tube).
From each of these four solutions, Jena glass tubes were also
made up for comparison. The pH was determined in all the
solutions before and after sterilization, which was carried out in
the autoclave at 118°C. momentarily. The results of these
series are shown in tabled.
From the table it is seen that the solution itself is very acid,
where it is not neutralized, and almost without exception the
INDOL TEST IN TRYPTOPHANE SOLUTION 87
hydrogen ion concentration increases during the sterilization. •
Furthermore, it follows from this that some alkali has been
leached from the glass of the ordinary tubes, because the values
of the pH of the Jena glass tubes are, consistently, lower (from
0.14 to 0.32) than for the others.
With these four sterilized solutions, indol tests were carried
out with eight different species of bacteria, of which three are
known to be strong indol liberators, namely Baci. coliy BacL
vidgare and Vibrio cholerae.^ The other five are not indole
Uberators. These species were Bact. aerogenes, a variety of
BacL Zopfii, isolated from soil of the northern coast of Green-
land, a motile non-sporeforming rod, isolated from the faeces
of a crow and finally a yellow, non-motile non-sporeforming
short rod isolated from the faeces of the musk ox. The two last
were also obtained from Northern Greenland.
Of all these strains, one platinmn loop from a twenty-fom-
hour broth culture was inoculated in each of the above mentioned
solutions.' After incubation for twenty-four hours at 37°C.,
they were examined for growth (turbidity), as well as for the
setting free of indol, by adding 5 cc. of the p-dimethylamidoben-
zaldehyde. According to ZipfeFs work, which I can confirm in .
this point, it is quite unnecessary to let the tryptophane cultures
stand longer than twenty-four hours at 37°C. If there is no
growth in this time, it is of no use to continue the observation.
The results of these series are given in table 2.
If we consider at first only the influence of the hydrogen ion
concentration, we find our suspicions confirmed that the non-
neutralized solution is too acid always to pei-mit the growth of
the organism wTiich is to be examined for indol Uberation. Bact.
wlgare and Vihrio cholerae do not grow and therefore naturally
cannot give the indol reaction in the solutions which are not
neutralized.
If we consider the residts from the solutions with and without
ammonium lactate, we may conclude from these experiments
* I wish to thank Prof. C. Kling, director of Statens Bakteriologiska Labora-
torium, for his kindness in supplying me with the cultures of V. cholerae and Baci,
typhi.
88
CHR. BARTHEL
that it is of no consequence whether this compound is present
or not. To be sure, in some cases the growth (turbidity) was
stronger in the tubes which also contain ammonium lactate,
but examples to the contrary are also to be noted, and in no
TABLE 2
CULTDBB
Bad. coli:
Growth
Indole reaction. . .
Bact, vtdgare:
Growth
Indole reaction...
V, cholerae:
Growth
Indole reaction...
Baci. typhi:
Growth
Indole reaction...
BacL aerogenes:
Growth
Indole reaction...
BacL Zopfii:
Growth
Indole reaction...
Bacteria from crow:
Growth
Indole reaction...
Bacteria from muak ox
Growth
Indole reaction. ..
+ AMMONXUM
LACTATS
NBOTBAL
pH-6.2Q
+ + +
+
+
+ + +
+ +
(+)
+ AMMONIUM
X«ACTATE
ACID
pH-4.83
+
+ +
WITBOCT
AMMOMXVM
LAOTATB
NBUTBAIi
pH-6.28
WITBOVT
AMMOMICTM
LACTATE
ACID
pH-4.83
+ +
+ .
+
+
(+)
—
+
—
+ +
—
■f
—
+
++
++
(+)
■f
++
f
cases has the indol reaction given different results in the tubes
with and without ammonixun lactate.
The results of the experiments here telated are that the solu-
tion of Zipfel is equally satisfactory even without ammonium
lactate^ but that imder all conditions it must be neutralized.*
* It may happen occasionally that the tryptophane solution gives satisfactory
results without neutralization, but this probably generally depends upon an
especially strong leaching of the alkali from the glass during the sterilisation.
THE NATURE OF HEMOLYSINS
J, T. CONNELL and L. E, HOLLY
Ann Arbor, Michigan
Received for publication July 20, 1920
Attention was first called to the fact that some bacteria pro-
duce hemolysins when Ehrlich (1898) showed that the bacillus
of tetanus produced a substance which he called tetanolysin.
The discovery of the existence of this lysin was rapidly followed
by the announcement of other bacterial hemolysins, such as
pyocyanolysin (Bulloch and Hunter, 1900; Weingerofif, 1901),
staphylolysin by Neisser and Wechsburg (1901), streptolysin by
Besredka (1901), typholysin by E. and P. Levy (1901), megath-
eriolysin by Todd (1901), etc.
It was soon shown that these lysins were characteristic of the
organisms that produced them. For instance the staphylolysin,
according to Neisser and Wechsburg, is injured by heating to
48®C. for twenty minutes, and destroyed at 56®C. for twenty
minutes. Pyocyanin is destroyed by heating to 100°C, for
fifteen minutes if it is free in the filtrate, but if the organisms are
present it requires a higher temperature, and typholysin is not
destroyed by boiling. Streptolysin requires 70°C. for two hours.
The majority of the lysins give rise to antilysins which are
specific, though streptolysin is an exception. In fact the abil-
ity of a lysin to call forth an antilysin seems to run parallel with
the ability of the microorganism producing the lysin to call
forth antibodies to itself.
Lubenau (1901) considered the possibility that some substances
which are known to be present in the mediiun may at times
be responsible for the hemolysis. He tested the hemolytic
power of sodiiun darbonate, ammonia, glucose and lactic acid,
and showed that the strengths of these substances required to
hemolyze are rarely ever present at the time the hemolysin is
89
JOUBNAI* or BAOTBRIOLOOT, TOL. TI, NO. 1
90 J. T. CONNELL AND L. B. HOLLY
active. Bulloch and Hunter showed that while a culture of
P«. pyocyanea is highly alkaline yet when the pH is brought back
to near the neutral point it is still hemolytic though less so.
This statement has been denied by Jordan who maintains that
the hemolysis in this case is due to alkali.
In view of the light that has been thrown by Warden's work
upon the composition of organisms, particularly in respect to
their fatty complexes, it seemed logical to us that these fat
antigens should be investigated as to the possibility of their
playing a part in hemolysin production. This idea seemed
particularly attractive because those organisms such as StrepUh
coccus and B. megatherium which produce hemolysin early in
their growth, and which also yield the most powerful hemolysins,
are Gram positive, and the Gram positiveness of an organism is
known to depend upon the presence of unsaturated fats. It is
also well known that the unsaturated fatty acids and their salts
are much better hemolytic agents than the non-volatile, satu-
rated acids. We are aware, also, of the fact that if . the fatty
acid complexes should play a part in hemolysis the action would
not be that following their simple suspension in salt solution
because of the factors of a colloid nature introduced by the
broth menstrumn.
With these ideas in mind we decided to see if it were possible
to produce an artificial hemolysin, using the fat complexes which
were characteristic of the organism whose lysin we were trying
to imitate. In order to do this ideally we realized that we must
copy as closely as possible the condition existing in the medium
at the time the hemolysin is at its height. The hemolysin first
studied was that of the Streptococcus. The medium used
throughout this work, called the standard medium, consisted of
a veal infusion broth containing 2 per cent bactopepton and
0.5 per cent NaCl. The pH was varied from 7.1 to 7.9. In
growing the Streptococcus organisms 10 per cent rabbit serum
was added before inoculation. The cells used in the hemolytic
experiments were fresh rabbit cells washed four times with 0.85
per cent salt solution, and made up in a 2 per cent salt solution
suspension.
*
THE NATURE OF HEMOLTBINS
91
Figure 1 is typical of a number of curves derived when two
different kinds of media were used, each having an original pH
of 7.2, one being the standard medium, the other the standard
plus 0.2 per cent glucose. All tubes were heated to 37°C. before
/\taH.
9
/O
«
/
\
\
\
Ji
1
\
1
\
1
1
1
'
\
Si
sy
C6
/
i
/
\
«
\
\
1
t
1
I
1
1
1
\
1
1
i
t
I
\
\
1
1
1
t
1
• \
1
\
4
L 1
^ i
i 1
f A
f A
«. }
Y A
^ /
f J
o J
tr^
Fig. 1. Solid Like, Plain Bboth Standard Medium
Bboksn Line, Glucose Bboth Standabd Medium
inoculating, and then inoculated with a 4 mm. loopful from a
twelve hour 10 per cent serum-broth cultiure of Sixe'pUKiOCCiJiJ^
hemolyticus. The tubes were incubated at 37®C. and every two
hours one tube of each kind of mediimi was removed, a part
being centrifugated for one-half hour at 1800 revolutions per
minute, and the pH of the remaining portion determined. Then
0.1 CO. of the supernatant fluid was added to 1 cc. of cell suspen-
sion and placed in a water bath at 37°C. for one hour. The
abscissae of the chart represent minutes required for complete
. hemolysis, the ordinates showing the age of the culture.
92 J. T. CONNBLL AND L. £. HOLLT
The pH of the standard mediuia was found to change to 7.0
at eight hours returning to about the original reaction at from
eighteen to twenty hours. The pH of the medium containing
glucose rose to 5.58 at twelve hours and returned to 6.10 at
twenty hours.
The striking feature in the chart is seen to be the disadvants^e
of even small amounts of glucose for the production of hemol-
TABLE 1
A. Broth containing 40 mgm. per liter of K salts antigen.
B. Broth containing 40 mgm. per liter of Na salts antigen
O. Broth containing 40 mgm. per liter of fatty acid antigen
1 cc. of A plus 1 cc. of 2 per cent rabbit cell suspension ++20 minutes
1 cc. of B plus 1 cc. of 2 per cent rabbit cell suspension ++20 minutes
1 CO. of C plus 1 cc. of 2 per cent rabbit cell suspension ++25 minutes
++ indicates complete hemolysis.
— indicates no hemolysis.
The above mixtures remained perfectly clear. They were completely inacti-
vated upon heating at 65°C. for thirty minutes.
ysin. Not only was the hemolysin weaker but of much shorter
duration, though the specimens were centrifugated in the same
centrifuge for the same length of time.
We also determined the strength and duration of hemolysin,
starting with a pH of 7.8 in the standard broth, but found no
striking difference from that of the 7.2. In growing these cul-
tures and in testing the strength of the hemolysin and the time
in which it appeared, two points were impressed upon us, first,
that noted by other workers, that the hemolysin occurs earlier
and is much stronger if the culture from which the transplant is
taken is young, preferably not over twelve hours old, second,
that using 0.1 cc. of culture for the transplant instead of a loop-
ful caused the hemolysin to appear earlier in the incubation.
In attempting to produce an artificial hemolysin the standard
medium was used. We omitted the serum because it was found
that it distinctly interfered with hemolysin production, just as
it also interfered with the lytic power of natural hemolysin if
added after the lysin appears. We believe that the function of
the serum in growing Streptococcus is to insure rapid and abun-
dant growth, which is apparently essential for the production of
THE NATmiE OF HEMOLYSINS 93
ly&n, and that the colloidal property of the serum which inter-
feres with the action of the streptolysin is undoubtedly destroyed
by the growth of the organism. We shall show further on that
serum added to a medium in which an organism (J5. megatherium)
produces strong lysin without it, interferes markedly with lysin
production.
The antigen used was the fat complex, in the form of the fatty
acids and their salts, found by Warden to be characteristic for
the Streptococcus. The sodium and the potassimn salts of the
complex were made up in alcoholic solutions of such strengths
that 1 cc. contained respectively 10 mgm. and the solution of the
fatty acids such that 1 cc. contained 20 mgm. and consequently
the amounts of alcohol neoessary to add to secure the concen-
tration of antigen desired was never sufficient to cause a change
m the appearance of the broth or to have any hemolyzing effect
on the red cells. The antigens were added by means of 1 cc.
pipettes graduated in himdredths and thoroughly mixed with
the broth, taking care to avoid foam. The amounts used varied
between 32 mgm. and 120 mgm. per liter, these quantities
apparently having no appreciable effect on the pH. We noted
in some of the broth that clouding appeared after about 45
mgm. per liter had been added, whereas other broths remained
clear with 60 mgm. per liter. One factor in this regard appeared
to be the color of the broth — ^the darker the color the more anti-
gen it would take up without clouding. Another important
observation was the variation in the amount of antigen per liter
required to make the broth hemolytic, in some instances 30
mgm. sufficing, in others 50 mgm. These differences were found
to be due to slight variations in the manner of emulsifjring and
in the time the mixtures were allowed to stand. Table 1 is
a specimen protocol of the hemolytic power of the artificial
emulsions.
Table 2 gives an example of the effect of pH upon the hemo-
lyzing power and the temperature of inactivation of artificial
emulsions made with the K salt and fatty acid antigens.
We realized that the broth containing the natural hemolysins
must be quite different from the artificial emulsions we were
94
J. T. CONNELL AND L. E. HOUiT
working with because of the action (digestive and otherwise)
upon it of the microorganisms. What probably is more impor-
tant is that it contained emulsifying substances which were
TABLE 2
A. pH of broth 7.1 with 60 mgm.
B. pH of broth 7.1 with 60 mgm.
C. pH of broth 7.4 with 60 mgm.
D. pH of broth 7.4 with 60 mgm.
£. pH of broth 7.9 with 60 mgm.
F. pH of broth 7.9 with 60 mgm.
K salt antigen per liter
acid antigen per liter
K salt antigen per liter
acid antigen per liter
K salt antigen per liter
acid antigen per liter
1 CO. of A plus 1
1 cc. of B plus 1
1 cc. of C plus 1
1 cc. of D plus 1
1 cc. of E plus 1
1 cc. of F plus 1
cc. rabbit
cc. rabbit
cc. rabbit
cc. rabbit
cc. rabbit
cc. rabbit
cell emulsion,
cell emulsion,
cell emulsion,
cell emulsion,
cell emulsion,
cell emulsion.
AT ONCS
OHB
BOUB
TWO
BO0BS
4-1-12'
+ +9'
++9'
++17'
++15'
++12'
++11'
++10'
++12'
++26'
++15'
++15'
++19'
++12'
++15'
++30'
++16'
++14'
MX/ FOB
TRIXTT
linfUTXS
++23'
++28'
-1 hr.
-1 hr.
++40'
++45'
From the above experiment it will be seen that the artificial hemolysin is in-
activated at 65°C. for thirty minutes at a pH of 7.4, but at concentrations of 7.1
and 7.9 the inactivation is only partial.
delivered into it with the disintegration of the bacteria. With
this idea in mind we tried the effects of some emulsifying sub-
stances to see if we could imitate the natural process more
closely, and to determine whether the broth would not hold
more of the fats without clouding. The substances chosen
were such proteins as hemoglobin, casein, and t3rphoid protein,
with which the fat antigen was emulsified, — ^imitating the con-
ditions we believe to exist in the germ bodies — prior to adding
to the broth. The following table is an example of the results.
TABLE S
A. 35 CC. of bi'oth to which was added slowly in fractions 5 cc. of a solution con-
taining 10 mgm. of typhoid protein and 2.4 mgm. of K salt antigen.
B. 35 cc. of broth to which was added in the same manner 5 cc. of a solution of
10 mgm. of casein with 2.4 mgm. of K salt antigen.
C. 35 cc. of broth to which was added in the sanle manner 5 cc. of a solution of
hemoglobin with 2.4 mgm. of K salt antigen.
THE NATURE OF HEMOLYSINS 95
The proteins were dissolved in 5 cc. of salt solution and the solution of antigen
mixed drop by drop with continual gentle shaking.
1 cc. of A plus 1 cc. of cell suspension ++ in 20 minutes
1 cc. of B plus 1 cc. of cell suspension ++ in 10 minutes
1 cc. of C plus 1 cc. of cell suspension ++ in 10 minutes
Control emulsions of like amounts of solutions of broth with the proteins alone
showed no hemolytic power.
All the above mixtures remained perfectly clear, and were inactivated at 65 ''C.
for thirty minutes. Other combinations were tried with amounts of fat antigen
varying from 40 mgm. to 120 mgm. per liter, and with quantities of protein
varying from 5 mgm. to 20 mgm. per 40 cc. These mixtures also remained per-
fectly clear.
The influence of the colloidal nature of the broth on these
artificial hemolysins was so apparent that we were desirous of
seeing whether alterations in the broth would affect any par-
ticular changes. To this end the ordinary standard broth was
passed through a Berkefeld filter before emulsification with the
antigens. A control unfiltered broth of pH 7.1 containing 32
mgm. per Uter of E salt antigen in amounts of 1 cc. produced
total hemolysis of 1 cc. of cell suspension in sixty minutes^
whereas the filtered broth containing the same amount of the
antigen gave no hemolysis whatever. By doubling the amount
of antigen added to the filtered broth the hemolysis appeared
and was complete in one hour. This experiment, repeated with
the Na salt and with the fatty acid antigen, gave similar results,
and appeared to indicate that filtration removed from the broth
particles of some material instrumental in hemolysin production.
After it had been found that inactivation of the B. megatherium
lysin could be brought about by various adsorbents, to be men-
tioned later, we attempted the same procedure with both the
natural and artificial streptolysin. The results appear in table 4.
The results of inactivation by means of the surface of defatted
colon bodies were the same as from starch. Also inactivation by
the same adsorbents in the ice box over night instead of at 45°C.
gave identical results. In short, the artificial antigen was
readily inactivated by these methods but the natural lysin was
not. We then tested out the inactivation of the artificial lysin
when produced in 10 per cent serum broth. As stated pre-
96 J. T. CONNELL AND L. E. HOLLY
viously it is difficult to produce artificial lysin in the presence of
serum, but it is merely a question, of adding larger amounts of
antigen to serum-broth than are required to render standard
TABLE 4
A. Twelve hour centrifugated Streptococcus culture
B. Artificial lysii^ with 60 mgm. K salts Strep, antigen
C. Artificial lysin with 60 mgm. Na salts Strep, antigen
D. Artificial lysin with 60 mgm. acids Strep, antigen
1 cc. of A plus 1 cc. cell suspension ++ iu 10 minutes
1 cc. of B plus 1 cc. cell suspension ++ in 12 minutes
1 cc. of C plus 1 cc. cell suspension ++ in 14 minutes
1 cc. of D plus 1 cc. cell suspension ++ in 15 minutes
To 5 cc. of A, B, C, and D there was added a definite quantity of starch sus-
pension and the tubes were placed in the water bath at 4i5*'C. for 1 hour, together
with control tubes without the starch suspension. After centrifugation of the
starch the lysins were tested as follows:
Aly Bl, CI, Dl, represent the lysins treated with starch
A2, B2, C2, D2, represent the lysins untreated
1 cc. of Al plus 1 cc. cell suspension ++ 40 minutes
1 CO. of Bl plus 1 cc. cell suspension —
1 cc. of CI plus 1 cc. cell suspension —
1 cc. of Dl plus 1 cc. cell suspension. —
1 cc. of A2 plus 1 cc. cell suspension ++ 18 minutes
1 CO. of B2 plus 1 cc. cell suspension ++ 20 minutes
1 CO. of C2 plus 1 cc. cell suspension ++ 20 minutes
1 cc. of D2 plus 1 cc. cell suspension ++ 20 minutes
broth hemolytic. Much larger quantities of antigen can be
added to serum-broth, if added in small amounts at a time,
without clouding, than to standard broth. As a result of this
experiment it was shown that with a Streptococcus serum-broth
culture fourteen hours old, centrifugated, 1 cc. of which hemo-
lyzed 1 cc. of cell suspension in twenty minutes and with an
artificial K salts hemolysin containing 300 mg. antigen per liter,
1 cc. of which hemolyzed 1 cc. of cell suspension in five minutes
attempted inactivation with the adsorbing substances in the ice
bbx and at 45^0. produeed.no such effect, i.e., neither natural
or artificial hemolysin was inactivated. This seemed to justify
the conclusion that the reason we were unable to inactivate the
THE NATURE OF HEMOLYSINS 97
natural streptolysin was because of the presence of the serum
and not because of any peculiarity of the lysin itself.
Several attempts were made to produce antilysin by injections
into animals of the natural streptolysin, the artificial lysin and
streptococci themselves, but the results were imsatisfactory.
This work is bemg continued and it is hoped we may report on
it later. This difficulty has been commonly encountered by
other workers (Besredka, 1903).
The second microorganism selected for observation was B.
megaOierium. We chose this bacteriiun because from the work
of Todd (1901) it was known to produce strong hemolysin in a
comparatively simple medimn, and give rise to good antilysin.
The hemolysin of this organism is also very stable which is an
advantage over streptolysin. The standard medium was used
in all the experiments. We found that the lysin appeared as
early as the tenth hour and lasted for weeks. The pH of the
cultures, determined at two hour intervals was found to change
to 7.2 or 7.3 when the original pH of the medium was 7. 8. The
addition of 10 per cent of rabbit serum to the standard medium
before inoculation gave very much weaker hemolysin than when
the standard broth was used alone.
The antigen used for the production of the artificial hemolysin
was the fat complex found by Warden, Connell and Holly to be
characteristic for the B. megatherium. The various solutions of
the antigen were made in the same manner as those used in the
work on the streptococcus, and the emulsification of the antigen
with the broth was carried out similarly. Tests showed that
artificial hemolysin containing 40 mgm. K salt antigen per liter
gave complete hemolysis, in 1 cc. doses, of 1 cc. of red cell suspen-
sion in thirty minutes, that of Na. salt antigen of equal strength
gave complete hemolysis in the same length of time; and that
containing the acid antigen produced, in the same dose, com-
plete hemolysis in twenty-five minutes. These artificial lysins
were inactivated at 65°C. for thirty minutes.
The following table is an example of the effect of pH upon the
hemolytic power, and upon the inactivation of the K salt and
acid antigen of the megatherium.
98
J. T. CONNELIi AND L. E; HOLLY
TABLE ft
A. Broth pH 7.1 plus 60 mgm. K salts antigen per liter
B. Broth pH 7.4 plus 60 mgm. K salts antigen per liter
G. Broth pH 7.9 plus 60 mgm. K salts antigen per liter
D. Broth pH 7.1 plus 60 mgm. acids antigen per liter
E. Broth pH 7.4 plus 60 mgm. acids antigen per liter
F. Broth pH 7.9 plus 60 mgm. acids antigen per liter
1 CO. of A plus 1 cc. cell suspension
1 00. of B plus 1 cc. cell suspension
1 CO. of C plus 1 cc. cell suspension
1 00. of D plus 1 cc. cell suspension
1 00. of E plus 1 cc. cell suspension
1 cc. of F plus 1 cc. cell suspension
These emulsions remained perfectly clear.
ONX
TWO
AT oircB
HOUB
BODBS
++28'
++17'
++17'
++35'
++»'
++20'
++36'
++26'
++26'
++20'
++13'
++15'
++30'
++13'
++16'
++30'
++18'
++»'
IHACn-
YATIOM
OMBBOUS
▲Ttt*C
-Ihr.
-Ihr.
++38'
-Ihr.
-1 hr.
The question of partial digestion of the broth on the part of
the microdrganisms during growth led us to attempt a similar
procedure in the effort to copy as closely as might be the^ germ
action in the production of our artificial lysin. We added a
small quantity of pancreatin powder to the broth containing the
antigen and digested the mixtures in the water bath at 45^C.
for one hour. The result of this experiment was complete
inactivation of the lysin, rather than one favorable to lysin
production. The question then arose as to whether the loss of
hemolytic power was not due to simple adsorption of the antigen
rather than to digestion, and the following experiment showed
such to be the case.
One cubic centimeter of artificial B. megatherium hemolysin
containing 100 mgm. of the K salts per liter hemolyzed 1 cc. of
cell suspension in ten minutes. Five cubic centimeter quanti-
ties of this hemolysin were treated with a definite amount of
starch, and the same quantities with defatted colon bodies.
These mixtures, together with 5 cc. controls of untreated hemo-
lysin were placed in the water bath at 45^C. for one hour, and
identical specimens were placed in the ice box over night. After
THB NATUBE OF HEMOLYSINS 99
centrifugation at 1800 revolutions per minute to remove the
adsorbent the fluids were tested for hemolytic power. Those
that had been treated with adsorbent were completely inactive
while the controls hemolyzed promptly in fifteen and in ten
minutes.
We then tested the natural hemolysia of the B. megatherium
to see if it could also be inactivated in the same manner. The
culture used was an eighteen hour standard broth growth centri-
fugated at 1800 revolutions per minute and the clear super-
natant fluid pipetted off. 0.25 cc: of this hemolysin hemolyzed
1 cc. of cell suspension in twenty minutes. The procedure with
the previous adsorbents was then repeated with this natural
lysin, with the result that the treated portions were found to be
completely inactivated while the untreated controls gave com-
plete hemolysis in fifteen minutes. In other words we found it
possible to inactivate the artificial and the natural lysin by
adsorption upon surfaces. Inactivation in this manner can be
rapidly effected by heating to 45^C. for one hour, a temperatiu^
at which ordinary organisms do not grow, or more slowly by
aUowing the mixtures to stand in the ice box over night. Appar-
ently the pancreatin powder acts, not by breaking up the fats
but rather by simple adsorption. Attention has been previously
called by others to the fact that pepsin and trypsin destroy the
lysin of Ps. pyocyanea.
It was also found that previous emulsification of the B. mega-
therium antigen mixtures with hemoglobin, casein and typhoid
protein before their addition to the broth gave results quite in
accord with those obtained with the Streptococcus antigen.
Todd showed, as mentioned previously, that the lysin pro-
duced by B. megatherium when injected into ammals gave rise
to antilysin. We injected several groups of rabbits, some with
natural lysin, others with the artificial hemolysin. These ani-
mals were given six injections subcutaneously, three at daily
intervals and then, after an interval of four days, three more at
daily intervals. On the seventh day after the last injection the
animals were bled from the heart and the serums allowed to
separate in the ice box over night. The serums were inacti-
100 J. T. CONNELL AND L. B. HOLLT
vated at 56°C. for thirty minutes following which they were
tested for antilytic power. Table 6 shows a typical protocol of
several experiments.
TABLE 6
HS. Serum of rabbit immune to natural hemolysin.
AS. Serum of rabbit immune to artificial lysin.
NS. Serum of normal rabbit.
A. Supernatant fluid from a centrifugated eighteen-hour
culture of B, megcUherium.
0.5 cc. A plus 1 cc. cell suspension ++ in 8 minutes
0'5 cc. A plus 1 cc. cell suspension -f4-
0.5 cc. A plus 0.2 cc. HS plus 1 cc. cell suspension —
0.5 cc. A plus 0.2 cc. HS plus 1 cc. cell suspension —
0.5 cc. A plus 0.2 cc. AS plus 1 cc. cell suspension —
0.5 cc. A plus 0.2 cc. AS plus 1 cc. cell suspension —
0.5 cc. A plus 0.2 cc. NS plus 1 cc. cell suspension ++
n 8 minutes
n 1} hours
in 1} hours
n 1} hours
n 1} hours
n 60 minutes
0.5 cc. A plus 0.2 cc. NS plus 1 cc. cell suspension ++ in 60 minutes
Further experiments on the immune bodies resulting from
immunization of animals with the artificial hemolysin of B.
megatherium are given in the paper on the Nature of Toxin by
Warden and ourselves.
DISCUSSION
We have dealt merely with the hemolysins of two organisms
streptolysin and megatheriolysin, both of which are very power-
ful and occur eariy in the growth of the organisms. The fonner
is only produced under special conditions and disappears in
twenty-four hours. The latter is elaborated readily upon very
simple media and remains active for weeks. The difference in
the ease with which these hemolysins are produced appears to
bear a direct relation to the rapid and abundant growth of the
bacteria, the hemolysin not being present in quantities sufficient
to detect imtil the growth is quite abundant. We are aware
that with the artificial antigens we have not obtained hemolysins
as active as those formed by the germs, but a discrepancy of the
sort was to be expected. The microorganism delivers its antigen
into the broth in a state of emulsification difficult to imitate with
only the colloid properties of the broth itself, and those of the
few proteins used as adjuvants to aid us in our attempts to
THE NATURE OF HEMOLYSINS 101
bring about an optimum surface for the adsorption of the anti-
gen. The variations in the quantity of antigen necessary to
produce hemolysin in the various broths used bear out the impor-
tance of the colloidal properties of the menstruum to which the
artificial antigen was added, and the fact that broth that has
been passed through a Berkefeld filter requires the addition of
more antigen tJt^an the unfiltered broth to make it hemolytic
seems also to emphasize the importance of surface in the pro-
duction of artificial hemolysin.
Another point that seems at first sight to afford a distinction
between the natural and artificial hemolysin is the clouding
that occurs with certain doses of the antigen. This variation is
however only apparent and can be avoided by emulsification of
the antigen before its addition to the broth, or by the presence
in the broth of just the proper surface. at the time of the addi-
tion of the antigen. Clouding depends in part on the rate at
which the antigen is added and upon the manner of adding it —
a considerably larger- amount can be introduced without forma-
tion of a cloud if the emulsification be made drop by drop slowly
and with constant gentle motion.
The points in which the natural and artificial antigens resemble
each other are as follows (a) both are comparably hemolytic;
(b) both are inactivated by heat at approximately the same
temperatures. The natural lysin of B. megatherium is usually
inactivated by heating to 56°C. for thirty minutes, though in
some specimens it was found to require GO'^C. for the same
length of time, while the artificial hemolysin when containing
40 to 60 mgm. of antigen per liter is inactivated at from 60° to
65°C. for one-half hour. These temperatures are suflSciently
close together for the discrepancy to be accounted for by the
crudeness of the artificial methods. Streptolysin was found to
inactivate at 70°C. for two hours by Besredka and by Ruediger
when serum medium was used and then diluted with salt solu-
tion before being passed through a Berkefeld filter. In our
serum-broth mediimi the streptolysin was inactivated at 65**C.
for one-half hour. We are forced to believe that the colloidal
state of the medium has considerable effect on the temperature
102 J. T. CONNELL AND L. E. HOLLY
at which inactivation occurs, (c) The natural and artificial
lysin of the B. megatherium is inactivated by adsorbents under
the same conditions. The natural streptolysin is not inactivated
by these agents, nor is the artificial lysin in the presence of
serum, (d) Analysis of the broth in which B. megatherium had
been grown for twenty-four hours showed the presence of approxi-
mately 60 mgm. per hter of the fat complex of the organism.
No analysis of the Streptococcus broth was made because of the
serum present, (e) Neither natural or artificial streptoljrsin
has thus far yielded satisfactory antilysin. Both natural and
artificial lysins of the B. megaOierium gave rise to strong specific
antilysins.
We have shown that certain artificial specific fat complexes
exhibit all the reactions characteristic of the bacteria examined.
We believe that the hemolysins of the organisms studied con-
sist of the respective fat antigens of the bacteria existing in
definite colloid states.
REFERENCES
Bbbbedka 1901 Ann. de Tins. Past., p. 880.
Bulloch and Hitnteb 1900 Gentbl. f. Bakt., Bd. 28, p. 866.
Ehblich 1896 Berl. klin. Wooh., p. 273.
Lbyt, E., and p. 1901 Centlbl. f. Bakt., Bd. 90, p. 405.
LuBBNAU 1901 Gentbl. f. Bakt., Bd. 30« p. 402.
NaiflSBB AND WscHSBXTBG 1901 Zeitsch. f . Hyg., Bd. 96.
RuBDiGBB 1903 J. A. M. A., 41, 962.
Todd 1901 Lancet, 2, 1663.
Wbd^obboff 1901 Gentbl. f. Bakt., Bd. 29.
THE NATURE OF TOXIN
THE ANTIGENS OP CORYNEBACTERnJM DIPHTHERIAE AND
BACILLUS MEGATHERIUM AND THEIR RELATION
TO TOXIN
C. C. WARDEN, J. T. CONNELL and L. E. HOLLY
Ann Arbort Michigan
Received for publication July 20, 1020
Previous work upon a considerable number of bacteria and
other types of living cells having demonstrated that each variety
of cell possesses a fat complex which is specifically antigenic/
it was determined to ascertain whether toxin-producing bacteria
might not also yield fat antigen complexes, and whether such
antigens bear any relationship to the toxins.
For this puri)ose we selected C diphtheriae and the B. megor
iherium, both of which yield heavy growths as well as produce
abundant toxin in suitable media. It has seemed advisable for
purposes of explanation and comparison to include the obser-
vations upon both of these bacteria in one paper. The toxm of
C. dipkOieriae induces strong antitoxin, but the antigen of the
organisms themselves is not conspicuous in the production ot
other immune substances such as agglutinins, precipitins and
complement fixing bodies, while on the other hand the B. mega-
therium gives rise to abundant antibodies of such nature together
with antihemolysins and antitoxins. Where the reactions of
these two organisms have characters in common they tend to
confirm one another, and the deficiences of one may be explained
by the data obtained from the other. Moreover, the work on
these bacteria was carried on at the same time, together with
that of Connell and Holly on the ''Natiure of Hemolysins."
' Warden, Jour. Infect. Dis., 1918, 22, 133; ibid., 1918, 28, 604; ibid., 1919, 24,
285; Warden and Connell, ibid., 1919, 26, 399.
103
104 C. C. WABDEN, J. T. CONNELL AND L. E. HOLLY
C. DIPHTHERIAE. THE ANTIGEN
The strain of organism used was the Park no. 8. The cul-
tures were preppjred in a manner calculated to produce the
greatest luxuriance of growth and the maximum of toxin. For
these purposes there was used veal infusion to which were added
2 per cent pepton and 0.5 per cent NaCl. The pepton was for
the most part a ''proteose" pepton prepared by the Digestive
Ferments Company which was found to yield toxin of high
grade. The proteose broth was adjusted to a pH of 7.9 with
NaOH prior to autoclaving. The organisms were trained to
rapid pellicle formation by frequent transplantations before the
final inoculations upon large surfaces of the nutrient broth .as
recommended by Bimker^ which were made upon shallow depths
of broth in Roux flasks laid on the flat and slightly inclined,
giving an area of 40 square inches per flask and a depth varying
from I to 1§ inches. Good pellicles covered the surfaces in
twelve hours, and the growths were maintained at 35®C. for
five to six days. It was essential that the medimn should be as
nearly fat-free as possible, and accordingly every precaution
was taken in that regard. Careful siphonage and filtration
while the broth was strongly acid, that is before the addition
of alkali, with strict attention to cleanliness of vessels and glass-
ware insured a medium containing a negUgible amount of fat.
At the conclusion of the incubation period the toxic broth
was separated from the germ mass by filtration through paper.
The germ residues were then examined for fat content by meth-
ods described in earlier articles. The total moist residue, a
portion of which was kindly supplied by Dr. Clark of the labora-
tory of Parke, Davis and Company, used in the examination
weighed over 1 kgm. The fatty acid complex obtained there-
from was found to consist of approximately 80 per cent of unsat-
urated acids, and 20 per cent of saturated, nonvolatile acids.
The toxin broth filtrates to the amount of 50 liters were also
examined and found to contain the same fat complex in quanti-
ties averaging 60 to 80 mgm. per liter, an amount equal to
about two-thirds of that obtained from the germ residue from
* Jour. Bact., 1919, 4, 4.
THE NATURE OF TOXIN 105
1 liter. The addition of cresols or other shnilar preservatives
to the Giiltures renders the toxin filtrates unfit for examination,
and the germ residues must be freed from it before accurate
examination of the fats can be made. The cresols pass unchanged
into the solvents along with the fatty acids, making their puri-
fication difficult and wasteful. A trace of cresol renders an
iodin determination fallacious because of the formation of addi-
tive compounds with the halogen in HiibPs solution.
Having determined approximately the composition of the
fatty acid complex derived from the germ bodies and toxin
broth, this complex was then tested against the serums of immu-
nized animals — it being the custom to check the tentative anal-
ysis in this manner. Knowing the complex to contain 'about 80
per cent of unsaturated fatty acid corresponding closely in its
various values to an oleic acid, and about 20 per cent of lower,
non-volatile saturated acids having a calculated M.W. of 250,
and melting poiut of 58°C., several trial artificial antigen com-
plexes were prepared, having approximately the same values,
from the purest obtainable fatty acids procured from sources
other than the germ bodies. These artificial antigens were:
No. 1, oleic acid 80 per cent, palmitic acid 16 per cent, myristic
acid 4 per cent. No. 2, oleic acid 83.3 per cent, palmitic acid
16.7 per cent. No. 3, oleic acid 84 per cent, stearic acid 16
per cent. (The specimen of oleic acid used was the normal
acid, having an I. V of 87.5). They were prepared for testing
by combining the Na salts of the acids in the above proportions
in alcohohc solution in such weights that 1 cc. contained 2 mgm.
of the complex, and to each 5 parts of the solution there was
added 4 parts of a 1 per cent alcohohc solution of cholesterol,
the latter being employed to furnish an adsorption surface for
the antigen proper.
Experiments in complement fixation were then made with the
serums of rabbits that had been immimized, some with washed
C. dipktheriae germ bodies, others with toxin. Three separate
tests were made with the serums of two groups of animals, using
the sheei)-rabbit hemolytic system, fresh guinea-pig comple-
ment, and a control antigen suspension in salt solution of thor-
oughly washed diphtheria bacilli from a twenty-four hoiur broth
I
106
C. C. WARDEN, J. T. CONNELL AND L. E. HOLLY
culture. The antigenic titer of th^ control antigen was 0.04 cc.
and that of the artificial antigens 0.1 cc. of emulsions made by
mixing 1 cc. of the alcoholic antigen solutions with 16.5 cc. of
salt solution. Two miits of amboceptor and 2 imits of comple-
ment were used, and 0.5 cc. of a 2 per cent washed sheep cell
suspension, all tubes being brought to a volume of 1 cc. with
salt solution. The first incubation was for thirty minutes at
37°C., the second for one hour followed by standing at 20°C.
for several hours. The serums of control and immunized rab-
bits were inactivated at 56**C. for thirty minutes. The results
of the tests are shown in tables 1, 2 and 3.
TABLE 1
First group of rabbits
BSBU1C8
1. Rabbit injected organiams
2. Rabbit injected organisms
3. Rabbit injected toxin. . . .
4. Rabbit injected toxin
5. Nonnal horse
6. Normal rabbit
7. Normal horse
8. Cpntrol, no serum
AMTZOSlfS
•
Control
germ
BUtpeii-
Bion
No. 1
No. 2
No. 3
++
++
++
++
++
++
■f +
++
++
++
4-f
++
++
++
++
++
—
—
—
++
—
+
—
++
+
+
±
++
—
—
^
—
Control
antbimx
antigen
db
TABLE 2
Second test of first group, following fresh bleeding ttoo days later
•
AMTIOKHB
8BBU1IB
Control
germ
BUBpension
No.l
No. 2
No. 3
Control
Streptoooe-
ouB antigen
1
++
+
++
—
+
2
++
+
+ +
±
—
3
++
■f
++
++
—
4
++
+
+ +
+-f
—
5
—
db
—
--
+
6
—
—
—
+
■f
7
++
—
■f+
+-f
++
Control, no serum
—
—
—
—
^
THE NATURE OP TOXIN
107
TABLE 3
Second group of rabbits, sixty days Utter
1. Rabbit injected organisms.
2. Rabbit injected organisms.
3. Rabbit injected organisms.
4. Rabbit injected tojdn
5. Rabbit injected toxin
6. Normal rabbit
7. Control, no serum
jamamm
Control
serm
Biupen- .
non
No.l
No.l
+
++
+
+
+
+
++
++
++
+
±
+
-
—
—
No. 3
In tables 1» 2, and 3, -4-+ "" no hemolysis, complete inhibition; + « partial
hemolysis; — « complete hemolysis, no inhibition.
From these tests it api>eared that artificial antige& no. 2 gave
results in closest agreement with the control diphtheria germ
suspension antigen. It was accordingly employed in the suc-
ceeding work. We do not agree with the statement of A.
Besson' to the effect that animals immunized with toxin show no
immime bodies in their serums.
Agglutination and precipitation experiments were not made
with these serums or this antigen^ nor was any attempt made,
for reasons mentioned earlier, to immunize animals with the
artificial antigen, such reactions being shown better with the
B. megatherium.
THE NATURE OF DIPHTHERIA TOXIN
The toxic broth as it comes from the filters is alkaline, having
a pH varying from 8.0 to 8.33. An experiment of Connellys
showed that the increased alkalinity might be due to the am-
monia, of which there was found 34 mgm. against 14 mgm. in
fresh broth. We had also shown that, among other changes,
the broth had become richer in fats, or salts of fatty acids, and
that these corresponded with those obtauied from the bodies of
the germs themselves.
• Fract. Bact., 1913, p. 269.
108 C. C. WARDEN, J. T. CONNELL AND L. E. HOLLY
We assume there can be no question that diphtheria toxin is
diphtheria antigen since its injection into animals produces a
specific antitoxin which unites with no other known antigen.
The concensus of opinion is that toxin is not a protein and does
not require protein for its development/ If we accept, then, as
one postulate the statement that toxin is specific antigen, and
as another that the specific fat complexes of cells constitute
their antigens, it follows that diphtheria toxin must be composed
of the diphtheria fat complex in one form or another, and it
should be possible to demonstrate the correctness or falsity of
our assumption by means of the artificial fat antigen in a certain
colloidal state.
In taking up this work we planned to commence with a broth
menstruum known to yield good toxin, and to combine with it
varying proportions of the fat antigen in various forms. Accord-
ingly a standard broth identical with that used for actual toxin
production was adopted. Artificial antigen no. 2 was prepared
in proper proportions in the forms of the fatty acids, the alkali
salts, Na and K, the ethyl esters, and the glyceryl and choles-
teryl esters. The ammoniimi salts were too imstable for xise
since in presence of Na ions in excess the NH4 ions are replaced.
Cholesterol was omitted from these antigens.
We regarded the broth as a highly complex colloidal fluid con-
taining proteoses existing as particles of varjdng colloidal dimen-
sions, as shown by ultrafiltration^ imknown organic matter
from the veal infusion, coloring matter, and various electrolytes
in addition to NaCl, all xmder the influence of a primary pH of
7.9. We assumed that the diphtheria bacilli, trained to the
most rapid reproduction on the most favorable mediimi must
also die and disintegrate rapidly according to a general principle
of life and death,* liberating their fat complex in an emulsified or
* Jordan, Genl. Bact., 1918| p. 266; Guinochet, Arch, de Med. exp., 1802, 4,
487; Hadley, Jour. Infec. Dis., 1907, Suppl. 3, p. 95.
' Bechhold-Bullowa, Colloids in Biol, and Med., 1919, p. 99.
* Vesilova, Russk. Vrach., 1915, 9, 205; Park and Williams, Pathol. Microorg.,
1920, p. 343. As an adjunct to the ''life and death'' principle in accounting for
the death of microorganisms, in fluid cultures at a time when the quantity of
lysin or toxin is at a maximum, is the fact of the existence in the fluid of the
THE NATURE OF TOXIN 109
•
colloidal form, which then, by reason of the necessity for such
surface-tension-lowering substances to collect at the interfaces
between dispersed and watery phases, become adsorbed upon
colloidal particles of a certain size in the broth, forming, with
electrolyte, an adsorption entity constituting toxin. We do
not believe there is any evidence whatever to show that toxin
exists preformed within the bodies of the bacilli and passes
through their membranes into the cultiure mediiun. The par-
ticles of the toxic adsorption aggregate must be very small as
we know from the ultrafiltration experiments of Bechhold' being
slightly larger than protalbumoses and smaller than the par-
ticles in 1 per cent hemoglobin solution. We realized the impos-
sibility of reproducing artificially all the changes imdergone by
mediimi and bacteria during the life of the culture, but we tried
to imitate as closely as might be the processes of colloidal nature
which we assumed on good evidence to take place.
The various methods used may be mentioned here: (a) The
fatty acid antigen in varying doses, in ether solution, was over-
laid on the surface of 100 cc. of broth in Erlenmeyer flasks of
250 cc. capacity. This was soon abandoned, (b) The fatty
acids were floated in bulk on the broth smface. This method
was also unavailable, (c) The fatty acids in alcoholic solution
were pipetted upon the surface of the medima, and also emul-
sified by mixing at once, (d) The same methods were used
with the K and Na salts, and with the ethylic, glyceryl and
cholesteryl esters. Several flasks of each description were always
made so as to permit of daily examination. All the operations
were carried out m a sterile manner. Departures were made
from the standard medium to include veal infusion without
peptone, peptone solutions alone, and, finally, to eliminate all
protein, colloids of mastic-fat in water and salt solution.
fatty acids, or their salts, derived from the bacteria, in just such amounts as
inhibit the growth of the germs, and at the same time cause the lysis of cells.
It is significant that the dose of the Na salts of the anthrax antigen just sufficient
to prevent the development in broth of the bacilli from spores, 60 mgm. per
liter, is that which toxic and lytic broths were found to contain, and approxi-
mately that which was added of the alkali salts to the artificial lysins and toxins,
as will be shown later.
' Loc. cit.
no
C. C. WARDEN, J. T. CONNELL AND L. E. HOLLT
The alcoholic solutions of the antigen fatty acids, salts and
esters were sterile and of convenient strengths for the pipetting
of small amounts to the broth with the minimum of alcohol.
Control experiments showed that the addition of corresponding
quantities of alcohol alone gave rise to no precipitation or other
appreciable change. The antigens were added in weights vary*
ing from 1 mgm. per 100 cc. to 20 mgm. per 100 cc. in a maxi-
mum of 1 cc. of alcohol/ without material change in the pH
either at once or with the passage of time. After inocidation
the flasks were placed, without stirring, save where emulrificar
tion was done at once, in the incubator at 35^ to 37^C. where
they remained undisturbed until examined. The pH of the
broth was also made to vary from the standard so as to try the
effects of such concentrations as 7.38, 8.0, 8.1 and 8.33. Some
of the flasks were made alkaline to the lower figures by ammonia
added in a sterile manner after autoclaving and cooling. Sev-
eral flasks were incubated imder lowered oxygen tension. When
a flask was removed from the incubator the pH of the contents
was taken, and the degree of clearness noted, as well as the
presence or absence of sediment and of faint sciun of imemul-
sified fat upon the surface. As a rule 2 cc. quantities taken from
the center of the fluid were then injected subcutaneously into
guinea pigs averaging 275 grams weight.
The results of these experiments are shown in tables 4 and 5.
TABLE 4
•
r ATTT ACnOB
•
TOTAI.
OUXKBA
PZ<M
ivumotMD
OIBO
8 mg. artificial diphtheria antigen added to broth Burfaoe.
Incubation at 37®C.. five to six days
82
15
25
79
Same dosage K or Na salts of fatty acids added to broth
surface. Incubation 37*C. five to six days
11
Mastic emulsions i alkali salts : no incubation
20
Number of pigs dying in 1 to 4 days. . .
Number of pigs dying in 5 to 14 days. .
Number of pigs dying in 14 to 30 days.
21
50
29
THE NATURE OF TOXIN
111
TABLE 5
Shomng a specimen portion of (he deaUi record in greater detail
pH
7.3
0
2
1
1
3
7.6
2
3
3
2
3
7.8
1
4
1
3
2
7.9
9
6
8
4
4
8.04
4
6
2
5-10
4
8.3
r*** •••• • •
Deaths
1
Aloohollo solution fatty aoids:
Incubatioii (days)
8-12
Deaths
4
Days to kill
10-14
Deaths
4
There were included in these tables only those animals dying
without infection which presented at autopsy a definite picture
of the macroscopic lesions characteristic of death from diph-
theria toxin, viz., great emaciation, hemorrhages into the cap-
sules of the adrenals and kidneys, enlarged and hemorrhagic
kidneys, injection and hemorrhage of the limgs. Free fluid in
the pleiural sacs and intestinal injection were variable signs.
The best results were obtained from dark colored broth inocu-
lated on the surface with 8 mgm. of the fatty acid antigen and
allowed to remain at 37®C. for five to six days, and which, at the
time of injection was clear, or with a fine colloidal haze, had a
pH of 7.9 to 8.1, a very slight or no surface pellicle and a slight
sediment consisting for the most part of crystalline phosphates.
Nearly all animals injected with such broth dkd. Filtration
through a Berkefeld filter greatly diminishea the toxicity.
Distinctly cloudy fluids did not give good results. The antigen
in the form of the K salts gave good results, while no deaths at
all were obtained from the broth containing the ethyl, glyceryl
or cholesteryl esters. We foimd that with the same broth
inoculated with the same dose of antigen, in the same manner
so far as control was possible, there were obtained fluids of
many degrees of emulsification from clearness to dense cloudi-
ness. The reason for this in the absence of contamination was
not apparent. We had difficulty also in making different lots
of broth alike, particularly in color, some being pale, others dark,
depending somewhat on the quality of the veal used for making
the infusion.
112 C. C. WARDEN, J. T. CONNELL AND L. E. HOLLY
A notable feature of the results was the irregularity in killing
time. Not infrequently a toxic broth which killed one guinear
pig in two days did not kill the other of the pair until much
later. We attempted to account for this peculiar result by
recognizing the extreme instability of such colloids, the slightly
different conditions encoimtered in the tissues of the various
guinea-pigs sufficing to alter the physical state of the injected
fluid.
Control guinea-pigs that died following injection of Strepto-
coccus and of Pneumococcus artificial antigen broth showed
pulmonary congestion and hemorrhages without particular
damage to kidneys or adrenals.
The most serviceable colloids of mastic were found, after
many trials, to be those prepared by adding to an alcoholic
solution of mastic of known concentration the desired amoimt
of alcoholic solution of fat antigen, and then emulsifying in
sterile water or salt solution by adding the alcoholic mixture to
the fluid kept in constant whirling motion. The emulsions were
pale white with orange colors by reflected light, and the par-
ticles were beyond the limits of microscopic vision. The clearest
results were obtained with colloids containing 5 mgm. of mastic
and 5 to 8 mgm. of the K salt antigen in 100 cc. of diluent, and
brought to a pH of 7.9-8.0 with NaOH. On standing the pH
shifts to the acid side. The injections were made with freshly
prepared sterile emulsions.
The pathological picture exhibited in guinea-pigs dying from
diphtheria and artificial toxin, while characteristic, presents
certain featiu-es which in the long run do not appear to be dis-
tinctive of that poison alone. Out of the control animals in
number at least equal to the determinants and kept under the
same conditions, there were found two pigs dead following
injections of supposedly tuberculous urine showing hemorrhages
into the adrenals, and one apparently normal pig, without
infection, showing the same lesion. The kidneys of these ani-
mals were not noticeably affected. These three control guinea-
pigs were the only examples however, in this and in previous
work upon fat antigens, in which lesions in any way similar to
those of diphtheria toxin were observed.
THE NATURE OF TOXIN 113
The diphtheria fatty acid-colloidal fluids used for injection
were not hemolytic for rabbit cells in the test tube, whereas
those prepared with the K salts were strongly so. Vesilloflf*
showed that the bacilli from very yoimg broth cultiu'es removed
by centrifugation and suspended in salt solution were hemolytic.
Lubenau^ states that broth cultures are hemolytic between the
second and fourteenth days, varying with different strains.
In seeking an explanation for the instability of our artificial
toxic colloids we were reminded of the fact that the methods of
emulsification so far employed must be of the crudest nature
compared with those which accompany the disintegration of the
bacilli. We regard the cells, bacterial or other, as consisting of
emulsion colloids of water, protein, fat, salts, etc., having at
their surfaces or limiting layers an excess of those substances
which lower surface tension and aid in regulating permeability,
and which, according to the principle of Willard Gibbs must
exist at the surfaces, namely emulsified fats, their acids and salts,
and protein. The colloidal state of the limiting surfaces is
probably different from that within the cells — a reversed type
of colloid like a wiater-in-oil emulsion, in contrast to an oil-in-
water emulsion to which one may compare the state of the
interior of the cells.^" Cells disintegrating or autolyzing in a
watery colloidal menstruum such as broth possess dispersion
means of remarkable power owing to the highly emulsified state
of the fats which, liberated under such conditions, must pass to
interfaces in the fluid in a manner far more delicate than we can
readily approach in an artificial way. With these ideas in mind
we believcKi we should be able to obtain greater stability in the
artificial toxins if we emulsified the fat antigen prior to adding it
to the broth. Accordingly we combined the antigen with solu-
tions of the commoner proteins at hand such as hemoglobin,
casein, egg albumen, gelatin, and a protein derived from the
BacL typhosum, substituting the alkali salts of the antigen for
the fatty acids because of their somewhat greater emulsifying
* Russk. Vrach., 1013, October 13, p. 235.
• Centr. f. Bakt., 1901, 30, 365.
1* Clowes, Science, 1916, 43, 750-757.
114 C. C. WARDEN, J. T. CONNBLL AND L. E. HOLLY
properties. The colloids formed in this manner were of great
interest. If to a solution of 10 mgm. of hemoglobin in 5 cc. of
salt solution there was added drop by drop the alcoholic antigen
solution a somewhat opalescent colloid resulted. When this
mixture was added to the standard broth in constant motion
drop by drop there resulted beautifully clear, stable liquids even
when the amoimt of fat antigen exceeded 200 mgm. per 1 liter.
When, however, the hemoglobin solution alone, or the hemo-
globin-antigen solution was added to the broth all at once,
instead of gradually, the resulting fluids became cloudy. The
same results were noted with fat-free casein-antigen and the
typhoid protein-antigen mixtures. The emulsions made with
fresh egg white and with gelatin were never perfectly clear.
Of particular interest were the colloids made with the t3rphoid
protem-antigen emulsions. The typhoid protem itself, of which
mention has been made in an earlier paper, is soluble in salt
solution, non coagulable by heat, contains but traces of amino
nitrogen and is highly toxic for laboratory animals in small
doses. It is toxic also when its solution is mixed with broth
by the drop method, 1 cc. of the fluid containing 0.25 mgm.
injected intraperitoneally into guinea-pigs being fatal in twenty-
four hours. On the other hand twice the dose produces no symp-
toms at all if the protein solution be added to the broth all at
one time. The addition of the fat antigen to the colloid increases
the toxicity, and gives to the autopsy picture its distinctive
character. Guinea-pigs dying from the effects of the protein
alone present no signs beyond sUght injection of the visceral and
parietal p)eritoneimi whereas those djring from the protein
antigen emulsions show characteristic signs of diphtheria toxin
poisoning. We do not believe that the .typhoid protein, derived
as it is from the germ bodies that have imdergone prolonged
defatting extractions with alcohol and with ether, represents
the proper protein of the bacteria during life, but this view does
not militate against the conception that the proteins of some
microorganisms liberated by autolysis in fluids may also be
somewhat toxic if emulsion in a proper colloidal state occurs.
We are inclined to the belief that the potentialities for toxin
THE NATURE OF TOXIN 115
production are always present when bacteria are permitted to
undergo lysis in fluid cultiu'e media, and that actual toxin pro-
duction depends first on the characters of the emulsified fat
antigen complex and second upon its colloidal arrangement.
The mixtures of hemoglobin and broth, and of casein and
broth did not show toxicity whereas these emulsions containing
the fat antigen were toxic.
Still another factor instrumental in the making of suitable
protein-antigen broth colloids is that of the color of the broth.
The pigment of broth appears to be a distinct aid to emulsifica-
tion. Very light colored broth is a much poorer colloidal mediiun
than one which is dark. Besredka^^ noted that the filtrates of
his streptococcus lysin which had lost some of the color dming
the filtration were impaired in hemolytic power. Connell and
Holly showed that a broth which had been passed through a
Berkefeld filter prior to the addition of artificial megatherium
antigen had practically lost its hemolytic power as compared
with the imfiltered broth containing the antigen. Very slight
alterations in broth lead to great colloidal changes.
A very important factor also is the maturation of the protein-
fat antigen-broth colloids. A period of time of at least one
hour at 20°C. after the mixing of the ingredients is essential to
the development of maximmn hemolytic and toxic power, after
which time, at 4^C. the activity remains stationary for a con-
siderable period and then gradually declines. Heat inactivates
these mixtures in a manner similar to true hemolysin and toxins.
The toxicity of the artificial fat-protein colloids is shown in
the specimen protocol given in table 6. All the injections were
TABLE 6
Artificial colloid no, i; 35 cc. of standard broth to which was added in divided
doses 10 mgm. of tjrphoid protein dissolved in 5 cc. salt solution.
Artificial colloid ru>, f : The same, to which the protein solution was added in a
single dose.
Artificial colloid no, $: The same, to which was added in divided doses 5 oc. of a
salt solution emulsion of 10 mgm. of tjrphoid protein with 4.8 mgm. of K salt
diphtheria antigen.
Artificial colloid No. SA: The same, with 5 mgm. of typhoid protein.
^1 Ann. de I'lnst. Past., 1901, 16, 880.
116
C. C. WARDEN, J. T. CONNELL AND L. B. HOLLY
TABLE t—C<nUinuti
Artificial coUoid no, 4: 35 cc. of standard broth to which was added in divided
doses 5 cc. of a salt solution emulsion containing 10 mgm. of fat-free casein
and 4.8 mgm. of K salt antigen.
Artifidal eolMd no, 6: The same, with 10 mgm. of hemoglobin substituted for the
casein.
Artificial colloid no. 6: The same, with 10 mgm. of gelatin substituted for the
hemoglobin.
Artificial colloid no, 7: The same, using 100 mgm. of fresh egg white as protein.
AMOUNT
QVISKA
INJBOTBD
PIO
IMTBA-
BB8ux;n
NUMBBB
PBBITONB-
AXXT
Guinea-pigs injected with colloid no. 1
1
2
3
4
5
Died in 12 hours, intestines hemorrhagic
Died in 4 hours, intestines hemorrhagic
Died in 4 hours, intestines hemorrhagic
Lived
Lived
Guinea-pigs injected .with colloid no. 2
6
7
8
No s3rmptoms
No symptoms
No S3rmptoms
Guinea-pigs injected with colloid no. 3
9
2.0
Died 4} hours; typical lesions
10
2.0
Died 5 hours,
; typical lesions
11
2.0
Died 3} hours.
; typical lesions
12
2.0
Died 7 hours,
; typical lesions
13
2.0
Died 6 hours,
; typical lesions
14
1.0
Died 7 hours,
; typical lesions
15
0.5
Died 15 days
16
0.5
Lived
17
1.0*
Lived
18
1.0*
Lived
19
2. Of
Lived
20
2.0t
Lived
21
2.0t
Lived
^ Plus 260 units antitoxin,
t Plus 500 units antitoxin.
THE NATURE OP TOXIN
117
TABLE tt—CoMliitfctf
UX/SB
Guinea-pigs injected with colloid 3a
22
23
Died second day; typical lesions
Died third day; typical lesions
Guinea-pigs injected with colloid 4
24
2.0
Died third day; typical lesions
«
26
2.0
Died fourth day; typical lesions
26
1.00*
Died seventh day; fair lesions
27
l.OO*
Died seventh day; fair lesions
Guinea-pigs injected with colloid 5
28
2.0
Died third day; typical lesions
20
2.0
Died first day; typical lesions
30
2.0
Died fifth day; fair lesions
31
2.0
Died tenth day; typical lesions
Guinea-pigs injected with colloid 6
33
33
Died second day; good lesions
Lived
Guinea-pigs injected with colloid 7
34
35
Lived
Lived
made intraperitoneally into guinea-pigs of 250 grams average
weight. The autopsies showed the characteristic lesions. All
the colloidal fluids were matured for one and one-half hours at
20^C.
The neutralizing action of antitoxin upon artificial toxin is
indicated in the foregoing table. The dose of toxin used was one
always fatal to guinea-pigs in six to eight hours. It woidd have
occasioned no surprise had antitoxin failed to protect, since at
best we had only hoped to approximate the toxic colloid in our
artificial mxtures, but the experiments while they have not been
118 C. C. WARDEN, J. T. CONNELL AND L. B. HOLLY
carried on to the extent one would desire seem clearly to indi-
cate a protective influence, specific or otherwise, but propor-
tionate to dosage, on the part of the antitoxin.
Further observations upon the production of artificial toxin
mixtures have suggested the availability of emulsifying sub-
stances other than proteins, such, for instance, as the dyes, of
which Congo red has thus far alone been tried. This question
is of interest in connection with the coloring matter of broths
noted earlier.
B. MEGATHERIUM. THE ANTIOEN
The strains of B. megatherium were two in number, one of our
own, and that known as No. 7 kindly sent us from the Museum
of Natural History, the latter having been used and commended
by Rous, Robertson and Oliver."
Heavy cultures of the organism were grown for twenty-four
to thirty-six hours at 35°C. in Roux flasks on beef-peptone 1
per cent agar, the mass removed in small amounts of water and
saponified in the manner previously described. The collected
fatty acid complex was then examined and found to consist of
approximately 56 per cent of insoluble imsaturated fatty acid
and 44 per cent of volatile fatty acid. The saturated fraction
obtained by steam distillation had a melting point of 30°C. a
neutralization value of 233 mgm. NaOH, and a calculated M.W.
of 175, showing that it probably consisted wholly of capric acid.
The insoluble residue from the distillation, after conversion into
the Pb salts and extraction with ether, showed the absence of
further satiurated acids, and the fluid acid obtained by conver-
sion of the Pb salts gave an I.V. of 90, a MutraUzation value of
142 mgm. NaOH and a calculated M.W. of 283, data quite in
agreement with an oleic acid. The tentative formula for the
Megatheriimi antigen, then, consisted of oleic acid 56 per cent
and capric acid 44 per cent. This was different from any pre-
vious complex studied but resembled in physical characters
most closely that for B. arUhracis.
i« Jour. Exp. Med., 1919, 29, 283.
THE NATUKE OF TOXIN
119
The antigen in the form of the Na salts with cholesterol was
then tested for complement fixing power with the senuns of
rabbits immunized with washed Megatheriimi organisms^ and
with Megatherium hemotoxin. The procedm-e in this experi-
ment was identical with that used in testmg the Diphtheria
antigen. The results appear in table 7.
TABLE 7
BSBUMS
1. Rabbit injected, organisms.
2. Rabbit injected, organisms.
3. Rabbit injected, toxin
4. Rabbit injected, toxin
6. Rabbit injected, toxin
6. Normal rabbit
7. Normal
8. Normal
9. Normal
Control, no serum
ANTZaBNB
Control sferm
Artificial fat
Buspenaion
antisen
++
++
++
+4-
++
++
++
++
++
++
+
+
++
++
-f+ =■ no hemolysis, complete inhibition; + = partial hemolysis; — =
complete hemolysis, no inhibition.
Table 8 shows the results of the agglutination-precipitation
tests of the same serums with the artificial fat antigen.
TABLE 8
Each tube contained: Antigen solution 0.08 cc, serum 0.2 cc. and salt solution
1 cc. The tubes after mixing and shaking were placed in the ice box over
night and read the following morning.
BKBUM NUMBBB
ACnVB BBBI71I
XNACTITATBD BBBUlf
1
+
+
2
• +
+
3
+
+
4
+
+
5
+
+
6
—
—
7
+ .
+
8
—
—
Control, no serum
—
—
+ a precipitation; — « cloudy, no precipitation.
JOUBHAL or BACTBBIOLOGT, VOL. YI, NO. 1
120
C. C. WARDEN, J. T. CONNELL AND L. E. HOLLY
Table 9 shows the results of the precipitation test with the
same serums.
TABLE 9
Antigen No, 1, True Megatherium toxin broth.
Antigen No. B, Artificial toxin broth, composed of 40 cc. broth containing 5
mgm. of Typhoid protein and 2.4 mgm. of the K salts of the Megatherium
antigen.
Each tube contained 0.5 cc. of antigen and 0.04 co. of diluted serum. Readings
taken as in table 7.
8KBUMS DILUTXD 1:00
SBBUmi DILXITBD 1:1S0
BBBXnil NCMBKR
(1)
Toxin
Aitifieiai toxin
Toxin
Artificy toxin
1
2
3
4
5
6
7
8
Antigen only
++
++
++
++
++
+
+
+
++
+
These experiments showed that in all probability the arti-
ficial antigen was approximately correct. We observed in these
and in later tests that many normal rabbits have natural anti-
bodies against the B. megaihenum and its toxin. This fact was
noted by Todd."
In order to test further the antigenic action of the artificial
fat complex, rabbits were immimized by divided S.Q. injections
of 0.5 mgm. doses emulsified both in broth and in salt solution.
Eight days after the sixth and last injection the rabbits were
bled and the senmis separated and inactivated at 56^C. for
thirty minutes. The following table shows the results of com-
plement fixation carried out in the manner previously described.
From these experiments it appeared that the senuns of rabbits
immunized with the artificial antigen of B. megatherium con-
tained agglutinating and complement fixing antibodies in fair
amount together with strong antilysins. Connell had pre-
i< Lancet, 1901, 2, 1663; Trans. Path. Soc. Lond., 1902, 63, 196.
THE NATURE OF TOXIN
121
TABLE 10
BXXUIIB
1. Rabbit injected, salt solution emulsion
2. Rabbit injected, salt solution emulsion
3. Rabbit injected, broth emulsion
4. Rabbit injected, broth emulsion
5. Normal rabbit
6. Normal rabbit
Control, no serum
ANTXOBNft
Mogatherium
Butpeiwion in
salt ■olution
++
+
+
Artificial
antigen
++
+
+
TABLE 11
The actme serum agglttHnaied a ettepeneian of washed Megatherium in salt eoluHon
Each tube contained: Salt solution suspension 1 cc. and 0.04 cc. serum. Tem-
perature 4°C. for two hours.
BBEUIIS
•UBPENSION
1
•
+
2
■f
3
++-I-
4
++
5
—
6
—
Control, no serum
—
+++ = complete agglutination and precipitation; ++ ™ almost complete
agglutination; 4- » partial agglutination; — = no agglutination.
TABLE 12
Showing (he presence of antihemolysis in the same serums which were tested against
the clear centrifugated lysin of a twenty-four hour veal-Bacto 'peptone 1 per cent
broth culture of which 0.6 cc. caused complete hemolysis of 1 cc. of a $ per cent
suspension of rabbit red cells in salt solution in eight minutes at S7^C.
Each tube contained: 0.5 cc. of fresh hemolysin, 1 cc. of cell suspension and 0.04
cc. of serum. The tubes were shaken and placed in a water bath at ST'^C.
for two hours, and then allowed to stand at 20^C. over night.
SBBUMS
• 0.04 cc. OP ACTIVB SEBUM
0.04 cc. OP iNAcrivx bbbum
DILUTBD 1/6 WITH BAX/I BOL17TION
1
....
_
2
—
—
3
—
—
4
—
—
5
++
■++
6
++
++
No serum
++
•
— = no hemolysis; ++ = complete hemolysis.
122
C. C. WARDEN, J. T. CONNELL AND L. E. HOLLY
vionsly shown that the serums of rabbits umnunized with Mega-
therium organisms and with toxin contained strong agglutinins
and precipitins. The Megatheriimi antibodies diminish fairly
rapidly in the serums of rabbits after having reached their
maximum. This fact was shown by repeated experiments upon
the antihemolytic power of the serums from both the series of
animals immunized with germ bodies and toxin, and with the
artificial antigen, they having been bled two days and again
four days after the first drawing. The subsidence in antibody
titer was shown to be p&rallel in the two series.
TABLE 13
Shows the hemolytic and toxic power of our strain of B. megatherium
Toxin no. 1: Twenty-four hour broth culture (composition given above) centrifu-
gated clear at high speed, of which 0.04 cc. hemolyzed 1 cc. of 2 per cent red
cell suspension in twenty minutes.
Toxin no, B: Six day broth culture, centrifugated clear. 1 cc. hemolysed 1 cc.
of red cell suspension in thirty minutes.
GUIIIBA
PIG NTTM-
1
2
3
4
▲MOUNT IN-
JBCTBD IN-
TOXIN
TBOPBBI-
NUMBER
TONBAIXT
2
1
2
1
2
2
2
2
RESULTS
Died in less than 12 hours
Died in less than 12 hours
Died in less than 12 hours
Died in less than 12 hours
Autopsies showed: Abdomen distended; peritoneum bright red, cavity con-
taining hemolyzed blood; small intestines hemorrhagic with hemorrhages into
the lumen; lungs slightly injected; bloody fluid in pleural sacs; heart muscle
injected; bloody transudate over thighs.
Guinea-pigs nos. 1 and 2 showed much more intense signs than nos. 3 and 4.
This experiment indicated that both the hemolytic and toxic
powers of twenty-four hour cultures of the strain were greater
than those of the six day cultures and that, hemolysin and toxin
were probably the same substance.
THE NATURE OF TOXIN 123
DISCUSSION
We believe with Bordet," Todd," Craw," and many others
whose work our observations tend to confirm that hemolysins
are true toxins. Some toxins may not be hemolytic for the
reason that the toxic particle may be of a size which does not
readily form adsorption aggregates with red cells, or because of
the protective action of proteins or other emulsifying substances.
All antigens so far examined are hemolytic in certain colloidal
states.
We have brought considerable evidence to show that the toxins
of C. diphth^riae and of B. megatherium probably consist of the
respective fat antigens of the organisms existing in definite
colloidal states, the particulate natiu-e of the complexes being an
indispensible factor. As will be stated in greater detail in
another paper the particulate character of all antigens is neces-
sary to the colloidal concept of immune processes. Just as
bacteria, parasitic in the blood and tissues of an animal, are
colloidal particles having specific and characteristic surface
chemistry, so also are the artificial fat antigens which have
been used as substitutes for the germ bodies. The mode of
action of such colloids is twofold, the primary one being that of
''surface," or particles, alone, the secondary one that of the
specific chemistry of the particles regulating the specificity of
the immune response. The injection of unorganized particulate
sxuface (kaolin, charcoal) leads to adsorptions and induced
toxicity of the plasma of the animal (anaphylaxis) ; injections of,
or infection by, bacteria or other cells also produce adsorptions,
but the character of the substances adsorbed must be different
for each species of cell, depending on the chemical complex
constituting its surface.
The result of such adsorptions on the body fluids is a depriva-
tion of some of their constituents, followed by the fluids com-
pensating, or making good their loss by an attack upon certain
1^ Bordet-Gay, Studies in Immunity, 1909, p. 186. et seq.
" Loc. cit.
»• Proc. Roy. Soc. Lond., Ser. B., 1905, 76, 179.
124 C. C. WARDEN, J. T. CONNELL AND L. E. HOLLY
groups of body cells which may contain the missing substances
upon their surfaces. There is considerable evidence pointing
to the fact that toxins and antigens need not act directly on the
cells but through the medium of the fluids bathing them. The
substances primarily adsorbed, when regained gradually and in
excess from the cells we regard as specific antibody.
The specific fat antigen complex of a cell may be one which
in its particulate character may produce poor or ready response
on the part of the body fluids, the result being inferior or strong
antibody, as for instance Streptococcus and F. cholerae; while on
the other hand the definite colloidal size of the antigen particle
may be necessary to powerful antibody production, for example
the C. diphiheriae; and again the colloidal dispersion of the
antigen may be variable and still yield all antibodies from the
agglutinins at one extreme to antitoxin at the other, as with
the B. megatherium. It is conceivable also that the fluids and
cells of the body respond better to some fat complexes than to
others, irrespective of colloidal arrangement. At best poor
antibodies result from attempted immunizations of laboratory
animals with the bodies of streptococci, and the same is true
with the artificial antigen and with the true streptococcus
hemolysin, but considering the extraordinary colloidal richness
of mammalian fluids and cells this idea does not seem so tangible
as another which is, briefly, that the antigenic complexes of
these microorganisms have not up to the present been employed
in a proper colloidal form, and we are inclined to think that
further study on the fluid media in which the bacteria are grown
will throw Ught on the obsciu-e problem.
A necessary corollary to these principles is that all antigen-
antibody reactions, from agglutination and precipitation through
complement fixation to toxin-antitoxin ag^egates, are but
phases of the same phenomenon acting from one extreme of the
colloidal realm to the other, and that all phases must be possible
with all cell antigens if only the proper colloidal state can be
found. Dean*' showed that complement fixation and precipi-
1' Lancet. 1918, 1, 45.
THE NATUMJ OF TOXIN 125
tation are phases of the same reaction, and J. Alexander^* has
seen the diphtheria toxin-antitoxm union by ultramicroscopic
methods.
It will be observe that no mention has been made of the
so-called '^lipoids." These substances play no part in the
phenomenon whatever. The term "fat" has been given a
somewhat elastic use to include the fatty acids and their salts
and esters. Cholesterol is not a lipoid but an alcohol. The
writers are of opinion that the evidence for the existence of hard
and fast lipoid substances such as lecithin and kindred bodies,
as such, in the fluids and cells of the body is very unsatisfactory
and doubtful. The mere fact that they may be extracted from
dried tissues by certain solvents does not si^iify at all that they
existed as entities therein. There are as many kinds of lecithin
as there are kinds of tissue, and, on the other hand, Barbieri and
his pupils^' failed to find a trace of lecithin in 8000 eggs. The
availability of, if not the necessity for, delicate, easily shifted,
labile adsorption compounds of electrolyte-fat-protein within
the body fluids is, however, undisputed, and it is probable that
the whole mechanism of immunity occiu^ in just such emulsion
colloids. The proper emulsification of bacterial and their
artificial antigens with emulsifying agents is regarded as the
sine qua non of toxin production. The r61e of cellular protein
aside from some such action does not appear to be paramount
and is not otherwise essential to antibody formation. The
"type" antibody response to protein and the "specific" anti-
body response to cells are but phases of the same process. Fat-
free protein, having no fat at its surface, has nevertheless chem-
ical configuration and particulate size, factors assuring adsorp-
tions and antibody production, and the antibodies respond
clearly to the antigen "type" only, lacking the sharp specificity
of cellular antibody for the very reason of the fat-free character
of the antigen.
The similar behavior of true and artificial lysins and toxins in
relation to heat, pH, reagents, adsorbents, effects on animals, etc.,.
>' Beehhold-BuUawa, footnote, p. 195.
» Gazcetta, 1917, 47, 1.
126 C. C. WARDEN, J. T. CONNELL AND L. E. HOLLT
has been brought out in the paper of Ck>nnell and Holly On
the Nature of Hemolysin."
We believe there has been adduced fair evidence warranting
the following tentative conclusions:
1. The C. diphtheriae and B. megatherium possess character-
istic fat complexes which are, under proper colloidal conditions,
the true antigens of these microorganisms. Artificial fat anti-
gens have replaced the antigens of the germ bodies in the various
immune reactions.
2. The lysins and toxins of the C. diphtheriae and the B.
megatherium are the same substances, being, respectively, the
specific fat antigens of the microorganisms existing in definite
and particular colloidal states.
3. Aside from colloidal or emulsifying activity cellular protein
appears to have no place in the immune reactions studied.
THE GAS PRODUCTION OF STREPTOCOCCUS KEFIRS
JAMES M. SHERMAN
From the Research Laboratories of the Dairy Division, United States Department of
Agriculture^ Washington, D. C,
Received for publication August 7, 1920
In her work on cheese streptococci, Miss Evans (1918) has
noted the presence in Cheddar cheese of gas-forming strepto-
cocci apparently similar to a streptococcus first isolated by von
Freudenreich from kefir. It was observed also that the gas,
which consisted entirely of carbon dioxid, was produced much
more abundantly in some media than in others. For example,
in trypsin-digested milk a relatively large amount of gas was
formed while in lactose broth a much smaller volume was
obtained, notwithstanding the fact that the latter medium
imderwent a vigorous acid • fermentation. This indicated that
the source of the carbon dioxid might be something other than
the sugar.
Aside from its purely physiological interest, knowledge of the
source of the carbon dioxid produced by this organism is of
scientific and practical importance in connection with the curing
of Cheddar cheese. Van Slyke and Hart (1903) showed that
carbon dioxid is given off from Cheddar cheese throughout the
Cluing process. The lactose of cheese, however, is entirely con-
sumed during the first few days; hence the source of the carbon
dioxid is not the sugar. The discovery by Miss Evans of the
occurrence of a gas-producing streptococcus in Cheddar cheese
naturally suggested that this organism might account for the
evolution of carbon dioxid from cheese of this type. In an effort
to throw some fight on this subject the work reported in this
paper was undertaken.
> Published with the permission of the Secretary of Agriculture.
127
128
JAMES M. SHERMAN
The two cultures employed in this work were obtained from
Miss Evans and belonged to the collection used in her studies of
cheese. For the determination of carbon-dioxid production the
special tube designed by Eldredge and Rogers (1914) has been
used. The cultures were grown in 30 cc. of broth and the car-
bon dioxid absorbed with barium hydroxid. Titrations were
expressed in cubic centimeters of ^ bariiun hydroxid neutralized.
Following the hypothesis that the carbon dioxid formed by
this organism might be derived from some source other than the
sugar, a number of experiments were run with various sugar-free
media but in no instance was a significant amount of this gas
TABLE 1
Relation of peptone concentration to carbon-dioxid production
MEDIUM NO. 1:
MSDIUMNO. 2:
MBDIUM NO. 3:
1.0 per cent peptone
CULTURB
1.0 per cent yeast
1.0 per cent NasHP04
0.3 per cent KHiPO«
0.2 per cent lactose
Same aa medium 1 except
2.0 per cent peptone
Same as medium 1 esoept
4.0 per cent peptone
2 ar
5.9*
5.9
5.8
2ar
5.7
6.0
5.7
96 gq
5.8
6.0
6.0
96 gq
5.8
6.2
5.8
* Cubio centimeters of ylr Ba(OH)s neutralised.
obtained. Other experiments were conducted in an effort to
show the relation between the amount of carbon dioxid produced
and the concentration of nitrogenous constituents of the culture
medium. For example the evolution of carbon dioxid was meas-
ured from media consisting of 0.2 per cent lactose, 1 per cent
dried yeast and varying amounts of peptone. The results of
such an experiment are shown in table 1. It may be seen from
this table that there was just as much carbon dioxid formed in
the broth containing only 1 per cent of peptone as there was in
those containing a greater concentration. The results of experi-
ments of this type and of numerous tests with various sugar-free
media of various compositions would not indicate that the gas
produced by this organism is derived from the nitrogenous
portion of the medium.
GAS PRODUCTION OP STREPTOCOCCUS KEFIR
129
Organic acids naturally suggested themselves as a possible
source of carbon dioxid. These were therefore tested in a broth
consisting of 2 per cent pf peptone, 1 per cent of dried yeast
and 0.5 per cent dibasic sodium phosphate. The sodium salts
of formic, acetic, propionic, butjrric, caproic, lactic, malic,
valeric, oxalic, tartaric, citric, and succinic acids were subjected
to this test but in no case was there an increase in carbon dioxid
over that obtained from the same medium without the addition
of an acid.
The' sugar content of the medium, of course, was considered
as a possible source of carbon dioxid and experiments were con-
TABLE 2
RsUUion of lactose concentration to carbon-^ioxid production
CUITUKB
MBDIUM NO. 1
4.0 per cent peptone
1.0 per cent yeeat
1.0 percent NMHPO4
0.8 per cent KH1PO4
MBDXVM NO. 2
Same aa medium 1
pliu 0.2 per cent
MKDIUM NO. 8
Same as medium 1
plus 0.4 per cent
lactoee
MEDIUM NO. 4
Same as medium 1
plus 0.8 per cent
2ar
2ar
96 gq
96 gq
0.6*
0.4
0.4
0.4
7.6
7.4
6.8
6.6
13.6
13.6
11.7
11.9
22.9
22 6
18.8
19.6
* Cubio centimeters of tv Ba(OH)s neutralised.
ducted in order to throw some light on this question. The
observation of Miss Evans, that a small amount of gas is obtained
in ordinary lactose broth whereas a^ greatly increased volume is
given off by the organisms when grown in digested milk, was
confirmed. Experiments conducted on this point, using a well-
buffered broth and varying the lactose content showed, however,
that the carbon dioxid produced increases with the increased
concentration of sugar. This is true up to the point where the
lactose content results in acid production beyond the amount
cared for by the buffer. In table 2 are given the results of an
experiment which shows the increase of carbon dioxid evolved
with the increase in lactose concentration. This experiment
was verified on several occasions.
130
JAMES M. SHERMAN
From observations on this point no hesitation is felt in con-
cluding that the source of the carbon dioxid produced in these
experiments was the lactose contained in the medium and not
any of the other possible sources.
It was thought, since the gas produced by this organism is
apparently derived from the sugar, that the greater production
of carbon dioxid in digested milk over lactose broth might be
explained by the greater buffer content of the milk medium.
In fact it was noted early in the work that the amount of gas
obtained from lactose broth was increased with the addition of
phosphate. We therefore compared in other experiments the
carbon-dioxid production of these cultures in digested milk
TABLE 3
Carbon-dioxide production in digested milk and in highly buffered lactoee broth
kCBDiuii:
Beef infusion
CULTURE
TBTP8IN-DIOE0TKD MILK
8.0
1.0
per cent peptone
percent NatHPOi
0.5
2.0
per cent KH«PO«
per cent lactoee
2
ar
27.0*
23.6
2
ar
27.7
23.2
96
gq
26.6
31.1
96
gq
26.3
30.1
* Cubic centimeters of tt Ba(OH)s neutralized.
and in highly buffered lactose broths. The data obtained from
one of these tests are given in table 3. It will be seen that the
carbon-dioxid production in lactose broth may be so mcreased
by an increase in the buffer content of the medium as to give
results comparable to those obtained from digested milk.
The conclusion to be drawn from the experiments reported
in this paper is that the carbon dioxid produced by organisms
of the Streptococcus kefir type, when grown in ordinary lactose
broths, is derived from the carbohydrate portion of the media.
With reference to the carbon dioxid produced in the ripening of
Cheddar cheese, after the original lactose content of the cheese
is exhausted, it would not be safe to draw definite conclusions
from these observations. However, from tests with this organ-
GAS PRODUCTION OP STREPTOCOCCUS KEFIR 131
ism in various sugar-free media, and in media containing a
variety of organic acids, it would appear doubtful whether it
could be held, responsible for the normal carbon-dioxid produc-
tion of Cheddar cheese. With the cheese-ripening problem in
view, other tests were run in which glycerol was used as a pos-
sible source of carbon dioxid. These experiments also gave
negative results.
REFERENCES
Eldbbdge, E. E., and Roobbs, L. A. 1014 The bacteriology of cheese of the
Emmental type. Centbl. Bakt. (etc.), 2 Abt., 40, 6-21.
Eyanb, Alice C. 1018 A study of the streptococci concerned in cheese ripen-
ing. Jour. Agr. Research, 18, 235-252.
Van Sltkb, L. L., and Habt, E. B. 1903 The relation of carbon dioxid to
proteolysis in the ripening of Cheddar cheese. N. Y. Agr. Expt. Sta.,
Bui. no. 231.
THE IMPORTANCE OF PRESERVING THE ORIGINAL
TYPES OF NEWLY DESCRIBED SPECIES
OF BACTERIA
C.-E. A. Vi^NSLOW
Ameriean Miueum of Natural Hiatory, New York City
Received for publication July 10, 1920
One of the most serious difficulties with which systematic bac-
teriology must contend is the incompleteness of the published
descriptions of new species and varieties. More care is now ex-
ercised than was formeriy the case but even the most exhaustive
descriptions must become incomplete as new diagnostic tests are
introduced in the future. The systematists who deal with the
higher plants have established the custom of preserving in
museum collections the actual type specimen on which a specific
description is established so that a later worker with new ideas
in regard to specific characters can always examine the original
plant and determine its actual characteristics.
In dealing with bacteria we cannot derive information of any
special value from the study of stained slides which would corre-
spond to the dead herbarium specimens of the botanist. The
only alternative is the preservation of living cultures and this is
a less satisfactory procedure in view of the fact that certain char-
acteristics may, and sometimes do, alter as a result of long-con-
tinued cultivation on artificial media. Nevertheless the preser-
vation of such hving t3rpes of cultures offers the only possibility
of stabilizing bacteriological nomenclature.
There are now at least three institutions in existence which
aim to preserve type cultures for the systematic bacteriologist.
Krai's Museum at Vienna (now under the direction of Dr. Pri-
bram) has survived the war and the revolution and has just
issued a new catalogue. The Museum of Living Bacteria at the
American Museum of Natural History in New York has now
been in operation for nearly ten years; and during the past year
133
134 C.-E. A. WINSIiOW
a third institution, the National Collection of Type Cultures,
has been established by the Medical Research Council of Great
Britain at the Lister Institute under the direction of Dr. J. C. G.
Ledingham.
Dr. Ledingham has asked for American assistance in his work
and it is obviously most desirable that the closest cooperation
should exist. He will furnish the American Museiun with any
new cultures he receives and we will send him all of ours that he
may desire. Such an arrangement will not only make for the
convenience of British and American bacteriologists, but will
o£fer a double insurance against the loss of strains of delicate
constitution.
The present note is presented to call the attention of the bac-
teriologists of America to the facilities offered at the Lister In-
stitute and the American Museimi and to urge upon all who
may describe new bacterial species the great importance of
promptly depositing with us the original type strain so that it
may be available for the comparative study of systematists in
futiu-e years.
PROGRESS REPORT FOR 1920 COMMITTEE ON
BACTERIOLOGICAL TECHNIC
H. J. CONN, Chairman, K. N. ATKINS, I. J. KLIGLER, J. F. NORTON, and
G. E. HARMON
Received for publication December 10, 1020
Committees dealing with various matters of bacteriological
technic have been appointed in the past by this Society and by
other organizations interested in bacteriology. There have been,
for example, the committees on standard methods of water
analysis and on standard methods of milk analysis of the Ameri-
can Public Health Association, also our committee on methods
of milk analysis to cooperate with the latter, and our committee
on the descriptive chart. With the exception of the committee
on the descriptive chart, all these committees have had for
their chief function the standardization of technic and the
establishment of official methods. Even the conmiittee on the
descriptive chart at first entertained the plan of establishing
official methods for pure culture study; but as the work of the
committee progressed, it proved that it might have a wider
usef uhiess as an agency through which different procedures might
be compared and their relative merits for different purposes
established without giving official standing to any one technic.
So important did this particular fimction of the committee
appear, and so many sunilar problems along other lines were
called to its attention, that finally the committee on the chart
resigned and a new committee was appomted m December 1919
to take up in the same manner various pomts of technic of interest
to bacteriologists. A continuation of the work on the chart
was assigned to this committee as part of its fimction.
The logic of such a committee as a part of our Society is
evident. The other bodies with committees on bacteriological
technic are in general interested in official control work and
135
JOVMSAL or BACTXBIOLOaT, TOL. YI, NO. 2
136 CONN, ATKINS, KLIGLER, NORTON AND HARMON
desire methods that give liniforin and reasonably reliable results
with as little labor as possible, rather than methods giving the
most accurate scientific data. As a society of bacteriologists,
however, we should be interested in the accuracy of technic
rather than in simple and inexpensive methods.
WORK ON THE DESCRIPTrVE CHART
The use of the descriptive chart has lately come to be mainly
for instruction purposes. Hence the recent committee on the
chart drew up a folder especially designed for instruction. There
has been considerable demand for this chart, but two modifica-
tions have been quite generally called for : its condensation into
smaller space, and the omission of the old and illogical group
nimiber. To see how generally this opinion is held among bac-
teriologists, an enquiry was addressed to each instructor who has
ordered the Society charts during the last two years. The
replies received have almost unanimously been in favor of a
single sheet chart without the group number. These two modi-
fications, it was pointed out, would make the chart more useful
not only to instructors but to investigators as well. Accordingly
both modifications have been adopted in the new chart which
the committee is proposing to the Society this year, together
with various minor changes which it is hoped wUl be found to
be improvements.
The new chart is like the instruction folder in the omission
of the detail which made the old card poorly adapted to the
instruction laboratory, but a few of the more commonly used
tests, omitted from the instruction chart, such as that for indol,
are included on the new form. By the use of finer type and the
reduction of the space left for sketches, all this material has been
condensed on two sides of an 8§ by 11 inch sheet. Nevertheless,
some blank space is still retained for sketches and for recording
the results of special tests. The group number, as such, is
omitted entirely; but aU the useful purposes of the group nimiber
are retained by adopting a new form of marginal characterization.
In place of the group number, an ''Index number" has been
REPORT OF COMMITTEE ON BACTERIOLOGICAL TECHNIC 137
substituted, the object of which is merely to assist the student
in filing a large number of the completed charts according to the
salient characteristics of the organisms described on them. Its
use, however, is optional; it is plainly stated to be intiended for
index purposes only; and as it does not contain the generic
symbol, there is no danger of its suggesting to the novice that
it is intended to supplant the specific name of an organism.
If this chart meets the approval of the Society, it will be
printed and will be ready for distribution at about the time that
this report appears in the Journal. The old charts will still
be kept on sale as long as there is any demand for them. All
the charts may be obtained from the chairman of this com-
mittee (address Geneva, N. Y.). A sample copy of the new chart
will be sent to anyone on request.
METHODS OF PURE CUI/TURE STUDY
The committee on the descriptive chart prepared two or three
reports on methods of piu-e culture study (1918, 1919, 1920),
which the present committee plans to keep up to date. To do
this, new methods are being investigated that they may be
published in future reports. The methods at present under
investigation are: methods of determining acid production from
sugars and other carbon compoimds; methods of determimng
diastatic action on starch; modifications of the Gram stain. A
preliminary pubhcatibn on the first of these problems has already
been made this year by Conn and Hucker (1920). There is
nothing yet ready for pubhcation on the other problems, further
than the material which appeared in the 1919 report of the com-
mittee on the descriptive chart.
METHODS OP COUNTING BACTERIA
0
There is no phase of bacteriological technic that has been
given more attention by scientific organizations than methods of
coimting bacteria. The reason for this is the importance from
the public health standpoint of knowing the number of bacteria
in any food or drink for human consiunption. It must not be
138 CONN, ATKINS, KUGLER, NORTON AND HARMON
forgotten, however, that there is one other equally important
object in counting bacteria, for it is only by this means that we
can determine the abundance of the organisms in any particular
habitat — ^a problem of value from the standpoint of pure science.
This latter aspect of the matter especially concerns this Society
rather than organizations interested in disease or public health.
The very fact that the subject is being so thoroughly investigated
from the standpoint of the sanitarian makes it all the more
important that it be studied by this Society also. Standardi-
zation of methods — ^which has been the chief aim of other organi-
zations taking up the matter — ^tends to prevent progress by
fixing the technic. To coimteract this tendency, the conmiittee
on technic plans to compare the various methods of counting
bacteria, laying chief stress upon their accuracy, rather than upon
their adaptabiUty to routine use.
There are three criteria by which methods of counting bacteria
can be judged: (1) agreement of duplicate determinations; (2)
size of the coimts obtained; and (3) actual accuracy of the counts.
The first of these, agreement of duplicate determinations, is the
object desired in control work, where incomplete coimts are
entirely suitable, provided a imif orm fraction of the total number
of bacteria is counted. Size of the coimts is the most commonly
used criterion as to the relative merits of different methods
of counting, because it is generally recognized that ordinary
coimts are but partial ones and the presumption is that the
higher count is the more nearly correct. Actual accuracy, how-
ever, although a far better criterion, is the hardest of all to apply,
because counts may be too high instead of too low, and there is
no absolute standard of comparison with which to check up
results. Even the best bacterial counts are but estimates because
the total numbers are too high to count with absolute accuracy,
and high magnification is necessary to see the individuals; so
the only way the accuracy of any one method may be determined
is by comparing it with other methods and discounting the
probable sources of error in each method.
There are three general tjrpes of methods by which bacteria
niay be counted : the dilution method, the plate method, and the
REPORT OF COMMITTEE ON BACTERIOLOGICAL TECHNIC 139
microscopic method. The dilution method (whereby a medium
is inoculated with progressively decreasing quantities of the
material imder investigation until a dilution is reached too great
to contain any bacteria) is cumbersome and is not applicable
to many types of bacterial flora. The plate method and the
microscopic method, each with various modifications, are in
common use and can be apphed to a great variety of bacterial
habitats. Each method has its advantages and each its dis-
advantages; but by using both methods and properly comparing
the results, it is possible to obtain very good information as to
the actual number of bacteria in the material imder investigation.
An admirable investigation of this sort, of the methods of count-
ing bacteria in milk, has recently been made by Breed and Stock-
ing (1920).
Although milk has been investigated in this way more than
any other material, there are other natural habitats of bacteria
where it may be fully as important to know the best methods
of detennining the actual numbers of organisms present as well
as to have official methods for routine use. There are, for
example: water, soil, sewage, vaccines, and various foodstuffs,
such as cheese, ketchup, butter, ice-cream, hamburg steak,
dried egg powder, and so forth. The field is too broad to cover
at once; but by attacking one problem at a time and by the
eventual establishment of various sub-committees, it is hoped
to round up the matter in time.
Shortly after the appointment of the conmoittee, the problem
of microorganisms in ketchup was referred to it. In this case the
work is practically limited to the microscc^ic method^ as the
processing of the material kills the greater part of the organisms
originally present. Counting is difficult, and yet results are
important because they have already been used in the control
of this food industry. It was pointed out to the committee
thart the industry would be glad to finance an investigation, but
wanted it entirely free from their influence. (The name of the
person or firm offering the money is not known to us.) The
matter was turned over to the New York Agricultural Experiment
Station, and it was found that they would gladly furnish the
140 CONN, ATKINS, KLIGLEB, NORTON AND HARMON
facilities for the work, but did not wish to accept money from
a commercial source. The Experiment Station, therefore, took
it up with the National Research Coimcil. Upon receiving the
endorsement of the Research Council of our Society, the National
Research Coimcil agreed to act as an intermediary and to become
responsible for the supervision of the investigation. In this
way a responsible, scientific, and disinterested supervision of the
work has been secured.
Although this work is no longer in the hands of the conmiittee
on bacteriological technic, and when completed will be published
as an independent piece of investigation, it is given its place
in this report because the problem was originally submitted to
the committee and the investigation was planned as a part of
the general committee program. It is regarded as merely a
beginning. Other similar problems are to be investigated in
the future. One that has already been referred to the committee
is the counting of bacteria in vaccines and other similar prepara-
tions. Anyone interested in this matter is hereby urged' to
correspond with the chairman of this committee on the subject.
STANDARDIZATION OF STAINS
As this committee is primarily interested in the accuracy of
technic, one of the first points that has been called to its attention
is the inaccuracy of certain procedures (e.g.. Gram stain) due
to the present unreliability of dyes used in staining. It was
suggested that the committee might undertake to test the various
stains on the market and to certify the reliable products, also
that it might do what it could to stimulate the production in
America of dyes needed but not at present manufactured in
this country. A circular letter was addressed to the members
of the Society and there was found to be much interest, a con-
siderable number of members volimteering to help in the work.
The matter has also been discussed with certain producers and
distributors of biological stains.
Th^re is plainly a demand for work of this sort, and the com-
mittee is willing to undertake it if it can be properly organized.
REPORT OF COMMITTEE ON BACTERIOLOGICAL TECHNIC 141
Certain difficulties are in the way, in establishing satisfactory
relations with commercial firms, and in securing the time and
labor necessary to organize the work; but it is felt that these
difficulties can be overcome. Further announcements will be
made if the present plans develop.
REFERENCES
Brebd, R. S., and Stocking, W. A., Jr. 1920 The accuracy of bacterial counts
from milk samples. N. Y. Agr. Exp. Sta., Tech. Bui. 75, 1-^.
Conn, H. J., and Huckbb, G. J. 1020 The use of agar slants in. detecting fer-
mentation. J. Bact., 6, 433-435.
Conn, H. J., bt al. 1918 Methods of pure culture study. Preliminary report
of the committee on the chart for identification of bacterial species.
J. Bact., 3, 115-128.
CoNNy H. J., BT AL. 1919 Methods of pure culture study. Progress report for
1918 of the committee on the descriptive chart of the Society of Ameri-
can Bacteriologists. J. Bact., 4, 107-132.
Conn, H. J., bt al. 1920 Report of the committee on the descriptive chart for
1919. Part I. Methods of pu^ culture study. J. Bact., 5, 127-143.
A STUDY OF THE VARIATIONS IN HYDROGEN-ION
CONCENTRATION OF BROTH MEDIA
LAURENCE F. FOSTER and SAMUEL B. RANDALL
From the Department of Pathology and Bacteriology^ University of California
Received for publication August 15, 1920
At the present time it would seem scarcely necessary to lay
emphasis upon the importance to bacterial growth and metabo-
lism of the reaction of the environmental culture mediimi. That
different degrees of acidity and alkalinity in media may pro*
foundly influence the morphology, rate of fermentation, pigment
production, growth, or viability of bacteria has been so thoroughly
recognized that in the routine preparation of culture media as
carried on in every bacteriological laboratory, the proper adjust-
ment of reaction is carefully regulated. The use of scales of reac-
tion such as that of Fuller, based upon adjustment to a definite
''degree" of titratable acidity, has permitted a certain amount
of uniformity, and in general, it may be said that these old titri-
metric procedures have served a veiy useful purpose. But with
the development, during the last few years, of the newer physico-
chemical conception of hydrogen-ion concentration the theory
of titration has undergone a fundamental change. As a conse-
quence many of the data obtained in earlier investigations are
of little value, having been based upon unsound premises.
An adequate conception of the far-reaching biological effects of
hydrogen-ion concentration may best be gained through a study
of the classic works of Michaelis (1914),' Sorensen (1912, 1909a,
1909b) and Clark and Lubs (1917a, 1917b, 1917c). The fol-
lowing statemei^t from the works of the last-named investigators
will serve to emphasize the importance to the science of bacteri-
ology of this modem conception of acidity and alkalinity:
^ Bibliography is found at the end of the third article, in this series, p. 231.
143
144 LAURENCE F. FOSTER AND SAMUEL B. RANDALL
Hydrogen-ion concentration influences the condition in solution of
every substance with acidic or basic properties — ^native proteins and
their hydrolytic products, amines and amides, carboxyl, sulphonic,
and phenolic compounds, even alcoholic compounds, as well as many
inorganic compounds. It has a large effect on the effective solubilities
and dispersion of colloids, upon determining tautomeric equilibria, and
in one way or another in governing the activity of catalysts such as
hydrol3rtic enzymes and oxidases. One or the other of these effects,
induced directly or perhaps indirectly by the hydrogen-ion concen-
tration must impress bacterial life.
That the expression of reaction in terms of titratable acid or
alkali does not adequately define the true reaction of a solution
has perhaps best been brought out by W. M. Clark (1915a) in
his admirable paper, ''The 'reaction' of bacteriologic culture
media." The objections to the older procedure may be sum-
marized in a quotation from Clark and Lubs (1917a) :
^ The titrimetric method, designed originally for the quantitative
estimation of strong acids and bases, cannot be applied to complex
mixtures of very weak acidic and basic groups such as are f oimd in the
constituents of most culture media. In so far as the method is used to
determine the "free acid" or to adjust to a certain degree of ''free acid"
it is an absolute failure when applied to culture media. There is how-
ever, an even more fundamental reason why the titrimetric method is
inappropriate. Two media adjusted to the same degree of acidity may
have widely divergent hydrogen-ion concentrations as shown by Clark
(1915a).
With the development of the hydrogen electrode, making pos-
sible a direct measurement of hydrogen-ion concentration, some
of the experimental and mathematical difficulties involved in the
older methods were obviated, but there still remained to be elab-
orated some simpler and more rapid procedure that would be
adapted to the adjustment of culture media and to the study of
reaction changes in bacterial cultures. Guidei} by the earlier
work of Friedenthal (1904), Sahn (1904), Friedenthal and
Salm (1907) who were the first to give a well worked-out series of
indicators, Sorensen (1909a) in 1909 published his colorimetric
method for determining hydrogen-ion concentrationsr^Since
HYDROGEN-ION CONCENTRATION OP BROTH MEDIA 145
this time a number of modified procedures have been suggested
by Levy, Rowntree, and Marriott (1915), Hurwitz, Meyer and
Ostenberg (1915, 1916); McLendon (1916); Bamett and Chap-
man (1918); Clark and Lubs (1916a, 1917a, 1917b, 1917c); Haas
(1919) ; so that at the present time it is a relatively simple mat-
ter to prepare and have on hand in the ordinary bacteriological
laboratory a suitable set of colorimetric standards for the meas-
urement of the hydrogen-ion concentration of media and cultures.
Tt is to Clark and Lubs (1917b, 1916b), Lubs and Clark (1915,
1916) that we are especially indebted for several new and valu-
able indicator substances as well as for a careful study of the
ranges and usefulness of an entire set of indicators for the exam-
ination of biological fluids.
Deeleman (1897) in 1897, using the titration procedure, noted
that media underwent certain changes in reaction during steriliza-
tion and sought to avoid such variation through the addition of
proper amounts of sterile acid or alkali to the autoclaved material.
Hesse (1904) used the same procedure in the adjustment of his
media and f mrther emphasized the fact that only that type of
glassware which yields no alkaU should be employed for contain-
ers, to prevent the increase in alkalinity that otherwise might
occur. According to S6rensen (1909a) however, such factors as
alkalinity from glassware and COt from the atmosphere exert
only slight effects if the medium in question is properly buffered.
Using the titration method, Anthony and Ekroth (1916) at-
tempted to bring media to a stable reaction by repeatedly alka-
linizing and autoclaving, but were unable to produce such a
stabilized condition even after many additions of alkali, supple-
mented by a total of fourteen hours autoclaving. They explain
the change as due to the formation of acid principles through hy-
drolysis. In one case five times the quantity of base needed was
added through an error, with the result that after several steriliza-
tions the reaction of the broth fell to the required level. Wright
(1917) has suggested that the amount of alkali indicated by titra-
tion is never sufficient to bring about a complete neutralization
of the medium, it being always necessary to add a considerable
excess over the amount indicated. On the other hand, Noyes
146 LAURENCE F. FOSTER AND SAMUEL B. RANDALL
(1916) states that properly prepared media do not increase ap-
preciably in acidity when the length of sterilization is increased
or when repeated autoclavings are carried out. It is a known
fact that many proteins may exist in solution only between cer-
tain limits of hydrogen-ion concentration and that slight changes,
at or near the critical zones, cause the formation of precipitates.
This phenomenon occurs in peptone solutions and as Kligler
(1917) has shown it is possible to establish the limits of Pb which
determine precipitation for each brand of peptone.* Cook and
Lefevre (1918) showed that as much as 12 per cent of peptone
may be lost through precipitation depending on whether this
material were added previous to coagulation and filtration or sub-
sequently. That a change in Ph accompanies such a precipitation
in media has been found by Clark (1915a) who reported a fall
in Pb of 0.80 (from 8.52 to 7.72) in an infusion broth containing
0.5 per cent KJB[P04. Itano (1916a) using the hydrogen elec-
trode in his Pb measurements, was able to establish a rough cor-
relation between the changes in Pb of an extract broth upon auto-
claving and the increase in COOH groups as determined by the
f ormol titration of Sorensen. Strangely enough the changes in Pb
reported by Itano were always of the nature of an increase in
alkalinity, and with this there appeared an increase in formol-
titrating nitrogen, indicating that hydrolysis had occurred. As
a result of boiling the broth for forty-five minutes this observer
found that the material became stable as regards further changes
in Pb. This last experiment, however, was tried only on media
adjusted between Pb 5.45 and 6.88. By sterilizing the constitu-
ents of his media separately it was possible to adjust to the desired
Pb and obtain values which remained fairly constant throughout
the entire experiment. Norton (1919) has reported that appreci-
able changes in the reaction of neutral and alkaline media, but little
variation in the acid range, result from sterilization. Davis (1920),
in recognition of the possibility of a change in the Pb of media '
adjusted in the alkaline range, has suggested that for the proper
preparation of a glucose broth of Pb 8.0-8.2 reactioq it is well to
s The symbol Ph of S5rensen is used throughout to designate the hydrogen-
ion concentration.
HTDROGBN-ION CONCENTRATION OF BROTH MEDIA 147
bring the material to an initial Ph of 8.6. Davis also emphasizes
the superiority of the autoclave over the Arnold for media steril-
ization pointing out that prolonged heating is always to be avoided
in order that the vitamine or hormone content may not undergo
destruction. On the other hand, Fennel and Fisher (1919) report
that in the preparation of over one himdred lots of beef infusion
broth the initial Ph of 7.8 did not show variation as a result of
autoclaving. In connection with his study of the effect of initial
reaction of a medium upon Corynebacterium diphtheriae, Bunker
(1919) noted certain reaction changes in his media upon steriliza-
tion. The variations appeared almost entirely on the alkaline
side and were always noted as increases in acidity.' Very re-
cently, Grace and Highberger (1920b) have carried out experi-
ments with extract broth which seem to indicate that changes in
reaction upon sterilization may not be of any greater order than
are the changes which a medimn may undergo simply upon stand-
ing, following autoclaving. The variations of greatest magnitude
occurred in the alkaline range and all changes were toward a
more acid reaction. No consistent tendencies could be detected,
therefore it was not possible to come to definite conclusions as
to the reasons for the observed changes. However, the possibili-
ties of the influence of glass and atmospheric COs, as well as of
slow hydroljrsis, were suggested.
Early in the present investigation it was noted that culture
media (broth) adjusted to definite Ph levels underwent changes
in reaction upon autoclaving, thus rendering difficult the prepara^
tion of broth of desired reaction. Consequently it was consid-
ered important to investigate these changes with a hope of finding
an explanation and perhaps of discovering some means of avoid-
ing them.
METHODS AND TECHNIC
Standard aolviions
All solutions were prepared according to the methods outlined
by Clark and Lubs (1916a, 1917a) from boric acid and salts which
> The term acidity in the present paper signifies true acidity as expressed in
terms of Pn*
148
LAUBENCE F. FOSTER AND SABiUEL B. RANDALL
had been recrystallized three to five tunes. Triple distilled water
served as solvent. The stock solutions, as well as the standard
buffer mixtures, were kept in heavily paraffined, glass-stopi)ered
bottles. Check determinations on the mixtures at the outset
and after a period of seven months showed that the standard buf-
fers, from bottles in which the paraffin was not broken, had re-
mained constant in Ph in spite of the fact that molds had devel-
oped in some of the liquids. Sorensen (1909a) reported a similar
observation on solutions after nine months standing. The de-
sired Ph ranges and the solutions used in their preparation are
given below :
m/5 Potassium acid phthalate, m/6 NaOH 4.0-5.8
M/6 KH,PO«, M/6 NaOH 6.8-7.6
m/6 HtBOi, M/6 KCl, M/6 NaOH 7.8-9.0
IndiccUors
The indicator solutions were the following:
GBBMICALNAMB
Ortho carboxy benzene aso di-methyl
aniline
Di brom ortho cresol sulphon phthalein
Phenol sulphon phthalein
Thymol sulphon phthalein (alkaline
range)
COMMON NAMB
Methyl red
Brom cresol purple
Phenol red
Thymol blue
COMOBK-'
TBATXON
XK SO PSB
CBMT
CtHaOH
perctnt
0.02
0.04
0.02
0.01
BAlfQB
Ph
4.4-6.0
6.2-6.8
6.8-8.4
8.0-0.6
Color standards
Color standards were prepared by adding 0.3 cc. of the required
indicator solution to 5 cc. of the buffer mixture. Tubes of color-
less glass and uniform bore, 4 by f inches were used for the color
standards as well as for the test liquids. Fresh standards were
made up each week, as fading is apt to occiu- if the solutions are
allowed to stand for a longer period. This is most pronoimced
in the methyl red series and least noticeable in the brom cresol
purple series.
HYDROGEN-ION CONCENTRATION OF BROTH MEDIA 149
Colorirnetnc determination of hydrogen-ion concentraiion
In properly buffered solutions it is possible partially to elimi-
nate such factors as color and turbidity by diluting the test fluid
with water. Preliminary tests showed that with broth and cul-
tures it was possible to dilute Ice. of the material with 4 cc. of
distilled water without altering the hydrogen-ion concentration.
Accordingly this technic was employed in all the determinations.
Freshly boiled and cooled distilled water was used for diluting
as preliminary tests had shown that unboiled water gave slightly
lower Ph readings. The Ph of the water itself was usually found
to rise from 4.8 to 6.8 upon boiling, probably due to liberation of
carbon dioxide. To eliminate factors of color and turbidity more
completely Walpole's (1911) method of superposition was used by
employing the comparator block described by Demby and Avery
(1918). All determinations were carried out at room tempera-
ture. The limit of error in the readings was 0.1 Ph.
The adjustment of broth media
One cubic centimeter of the broth was diluted with distilled
water (freshly boiled and cooled). Two acid solutions and two
basic solutions were kept on hand. They were n/1 HCl and an
3xact 1:10 dilution of the same; n/1 NaOH and an exact 1:10
dilution. A specially made micro burette, of 1 cc. capacity and
graduated to 0.01, contained the diluted acid or base. This
was added to the tube containing the medium, water, and 0.3
cc. of the proper indicator solution imtil the color produced therein
exactly matched that of the color standard of desired Pb. The
reading on the micro burette was then taken and by calculation
the amount of stock acid or base needed to adjust the total
amount of broth was determined. Following the addition of the
acid or base to the entire lot of medium a check determination
was always carried out. The broth was autoclaved at 15 pounds
for twenty minutes. In case this caused the formation of a pre-
cipitate the medium was filtered and subjected to a second auto-
claving for twenty to thirty minutes at 10 pounds pressure. The
low presfi[ure prevents a second precipitation of the medium. The
150 LAXJBENCE F. FOSTER AND SAMUEL B. RANDALL
Ph should always be taken on the broth following the final auto-
claving as well as at the outset of any given experiment.
The reason for this will appear in the experiments about to be
described.
In case the broth was to contain a sterile sugar this was added
aseptically in 10 per cent solution to the sterile medium to avoid
any possibility of splitting the sugar through heating. This pro-
cedure is especially important if the broth is adjusted in the acid
or alkaline range as it is a known fact that glucose and other
sugars are altered by heating with even small amounts of acid or
base (Mathews, 1916). Furthermore, Mudge (1917) has observed
an increased titratable acidity when sugars, at least disaccharides,
are autoclaved with media. By adding the sugar aseptically in
concentrated solution no change in reaction was ever noted.
Experiment I. The extent of the changes in hydrogeririon concen-
tration which broth media adjusted to different initial Pm
levels undergo upon aviodaving and standing
The imadjusted broth was divided into portions of 75 cc. which
were brought to values ranging from Ph 5.0 to 9.0 at intervals of
0.4. Five cubic centimeter amounts were then tubed and auto-
claved at 15 pounds for fifteen minutes after which they were
allowed to cool and Ph readings taken. The tubes comprising
each lot were divided into three sets, one of which was allowed to
remain at room temperature, another was placed in the ice chest,
while the third was incubated at 37®. After standing at these
temperatures for intervals of two, seven, and fourteen days tubes
were removed and Ph determinations made.
Five series were carried through and the data obtained are to
be found in tables 1 to 5.
I
II
III
IV
V
COMPOSITION or BBOTH
Beef infusion
Beef extract
Bacto beef
Beef infusion (repetition of I)
Beef extract (repetition of II)
BS8DIAS IN TABLN
1
2
3
4
5
HTDBOQEN-ION CONCENTRATION OF BROTH MEDIA
151
Reference to tables 1 and 4^ containing data for the two beef
infusion series, reveals differences in Pb changes as a result of auto-
claving. Whereas every tube of series I showed an increased
acidity upon sterilization, the tubes of series lY from 5.0 to 5.8
inclusive exhibited a decrease in acidity; those of Pb 6.1-7.3 suf-
fered no alteration in reaction, while those lying in the 7.8-^.9
range showed a definite increase in acidity. Upon standing, the
greatest changes in both series are manifest in the 8.6 and 9.0
TABLE 1
Experiment J. Changes in reaction upon autockunng and standing. {Betf
infusion broth)
Composition:
DistiUed water 1000 oo.
Chopped lean beef. / 300 grams
Peptone (Parke, Davis & Co.) 10 grams
NaCl 5 grams
BSfOBB
AUTO-
AirXB
AUTO-
BOOM TBMPBBATUBB
AFTBB DATS
XCa CHBffiP AJTBB DATS
IWOUBATOB ATTBB DATV
CLAvnra
2
7
14
2
7
14
2
7
14
5.0
4.8
4.8
4.4
4.7*
4.8
4.4
4.7*
4.8
4.4
4.7«
5.3
5.0
4.9
4.8
5.0*
'4.9
4.8
5.0*
5.0
4.8
5.0*
5.8
5.6
5.5
5.4
5.3
5.5
5.4
5.3
5.5
5.4
5.3
6.2
5.9
5.8
6.0
5.8
5.8
6.0
5.9
5.8
6.0
5.9
6.5
6.2
6.2
6.4
6.2
6.1
6.3
6.2
6.2
6.4
6.2
7.1
6.9
6.8
7.0
7.0
6.8
6.8
7.0
6.7
6.9
7.0
7.3
7.1
7.1
7.2
7.3
7.1
7.2
7.3
7.1
7.3
7.8
7.3
7.3
7.6
7.6
7.3
7.5
7.6
7.4
7.6
7.6
8.1
7.8
7.7
7.9
7.8
7.7
7.8
7.8
7.7
7.9
7.8
8.6
8.4
.8.4
8.4
8.1
8.4
8.4
8.1
8.4
8.4
8.1
9.0
8.6
8.6
8.5
•
8.2
8.5
8.5
8.2
8.6
8.6
8.3
^ The unexpected increase in alkalinity may have been more apparent than
real due to a fading of the standard buffer mixtures of the methyl red series.
tubes. These changes are in the nature of increases in acidity
and are as great in magnitude as those produced by autoclaving.
A possibility of this sort has apparently been overlooked by many
observers. No differences worthy of mention appear as a result
of storing the broth imder different conditions of temperature.
Passing to the two beef extract series (tables 2 and 5) a remark-
ably small number of alterations are notable in one case (V).
An increase in acidity of 0.2 Ph occurred in the two lots of highest
JOt7BMAL or BACTBBXOLOGT, VOL. YI, NO. 2
152
LAURENGB F. F08TEB AND SAMUBL B. RANDALL
Ph, namely the 8.6 and 9.0 tubes. These two lots were practically
the only ones to exhibit changes upon standing, the 9.0 registering
an acidity change of 0.7 Pb after fourteen days standing. In series
II (table 2) decreases in acidity are noted in the acid and alka-
line ranges upon autoclaving while within the range 6.6-7.3 the
broth remained unchanged. In every lot of this series the acidity
increased upon standing, the greatest changes occurring in the
TABLE 2
Experiment I, Changes in reaction upon autoclaving and standing. {Beef extract
broth)
Composition:
DistiUed water 1000 cc.
Liebig's beef extract 3 grams
Peptone (Parke, Davis & Go.) 10 grains
NaCl 6 grams
BirOBB
AITUI
BOOM TBlfPBBATUBB
ATPKB DATS
lOB CBBSr AITBB DATB
OKJUBAXOB AITBB DATE
AOTO-
AUTO-
CLAYIMa
oi<A.yxiro
2
7
14
2
7
14
2
i
14
6.0*
6.2*
5.3
4.6
4.7
5.2
5.1
4.8
5.3
4.8
4.8
5.3*
5.4*
5.6
4.7
4.8
5.5
6.1
4.8
5.5
4.8
4.8
5.8
6.0
6.1
5.2
5.2
6.1
5.2
5.2
6.1
5.2
5.2
6.2
6.4
6.3
5.6
5.6
6.3
5.4
5.6
6.3
5.6
5.6
6.6
6.6
6.6
6.2
6.3
6.6
6.3
6.4
6.6
6.5
7.0
7.0
7.0
6.8
6.8
7.0
6.8
6.8
7.0
7.3
7.3
7.3
7.0
7.0
7.3
7.0
7.0
7.3
7.0
7.0
7.7
7.9
7.9
7.5
7.8
7.9
7.4
7.6
7.9
7.4
7.8
8.0
8.3
8.4
7.8
7.9
8.4
7.7
7.9
8.4
7.6
7.9
8.7*
8.9*
8.5
8.4
8.6t
8.6
8.4
8.6t
8.6
8.6
8.7t
9.0*
9.2*
8.8
8.6
8.8t
9.0
8.4
8.6t
9.0
8.6
9.0t
* Precipitate.
t A slight fading of the standard buffer mixtures of the thymol blue series
may have occurred thus accounting for the apparent increase in alkalinity.
more acid and alkaline ranges. Here, as previously mentioned
in the case of beef infusion broth, the changes on standing seem to
be independent of the environmental temperature.
The results in the bacto-beef series (table 3) are similar to thoae
noted in the case of beef infusion. A decreased acidity in general
appears in the range, 5.0-6.2, the 6.6-8.2 tubes remain practic-
ally unchanged, while the most alkaline members, 8.6 and 9.0
show increases in acidity upon autoclaving. Upon standing at
HTDBOGBN-ION CONCENTRATION OF BBOTH MEDIA
153
the three different temperatures the same general tendencies as
have been observed in series IV may be noted.
It appears that there is no marked consistency in the variations
which a given type of broth medium may exhibit as a result of
autoclaving and standing. The same conclusions have been
reached by Grace and Highberger (1920b) working with beef ex-
tract broth. Itano (1916a) however, reported only decreases in
acidity in lots of extract broth adjusted throughout a wide range
TABLES
Experiment J. Changea in rectcHon upon autocUmng and standing, (Bacto-heef
broth)
Composition:
Distilled water 1000 cc.
Bacto-beef , 50 grams
Peptone (Parke, Davis A Co.) 10 grams
NaCl 5 grams
BBTOBS
AUTO-
▲tlTO-
CLATnro
AVTBBDATS
lOB CHnr AVTBB DATB
niCUBATOB Al^UI DAT!
di^yiira
2
7
14
3
7
14
3
7
14
6.0*
6.4*
5.5
5.4
5.6
5.5
5.4
5.7
5.4
5.5
5.7
5.4*
6.2*
5.7
5.8
5.6
5.7
5.7
5.5
5.8
5.7
5.7
5.S*
6.3*
6.1
6.0
5.9
6.3
6.0
5.9
6.1
5.9
5.8
6.2
6.6
6.6
6.3
6.2
6.6
6.5
6.4
6.4
6.3
6.2
6.6
6.6
6.6
6.5
6.4
6.6
6.5
6.4
6.6
6.5
6.5
6.9
70
7.0
6.9
6.8
7.0
6.9
6.8
7.0
7.0
6.8
7.3
7.6
7.4
7.4
7.3
7.5
7.1
7.5
7.4
7.4
7.5
7.8
7.8
8.0
7.9
7.8
7.9
7.8
7.7
7.9
7.9
7.8
8.2
8.2*
8.2
8.1
7.9
8.2
8.0
7.9
8.2
8.1
7.9
8.6
8.4«
8.3
8.3
8.2
8.4
8.2
8.2
8.4
8.4
8.3
8.9*
8.6*
8.5
8.2
83
8.5
8.2
8.2
8.6
8.3
8.6
♦ Precipitate.
of Ph. His medium contained 2 per cent peptone which, as is
well known, acts as a strong buffer. By sterilizing the compo-
nents separately he was able to avoid anything more than slight
alterations in reaction. No data were collected relative to the
possibility of changes upon standing. The discrepancies appear-
ing in the present beef infusion series were not so unexpected
when it is considered that two different lots of beef were employed
in their preparation, but the lack of uniformity in the changes
154
LAITItENCE F. FOSTER AND SAMUEL B. RANDALL
registered by the two beef extract series is not explainable ui)on
such a basis for the same components were used in the preparation
of each.
The remainder of the work has consisted of attempts to deter-
mine the causative factors in these reaction changes in order that
some procedure might be devised to obviate the effects produced.
Although certain investigators have pointed out that the glass-
ware employed may exert an effect upon the reaction of the con-
TABLE 4
Experiment 7. Changes in reaction upon autocUmng and etanding, {Beef
infueion broth)
Composition :
Distilled water 1000 cc.
Chopped lean beef 300 grama
Peptone (Parke, Davis & Co.) 10 grams
NaCl 5 grams
BSFOBS
Arrro-
AVTBB
AIJTO-
CLATXKO
BOOM TBMPBBATUBB
ArTBBDATS
ICB CHBR AVTEB DAT8
mOUBATOB AITBB HATS
CLAVINO
2
7
14
2
7
14
2
7
14
5.0*
5.3*
5.2
5.3
5.3
5.2
5.3
5.3
5.2
5.3
6.3
6.4*
5.6*
5.5
5.6
5.5
5.5
5.6
5.4
5.4
5.5
6.4
6.6
5.8
5.6
5.8
5.8
5.6
5.8
5.8
5.6
5.8
6.8
5.8
5.0
5.9
6.0
6.0
5.9
6.0
6.0
5.9
6.0
6.0
6.1
6.1
6.1
6.2
6.2
6.1
6.2
6.2
6.1
6.2
6.2
6.5
6.5
6.5
6.5
6.5
6.5
6.5
6.5
6.5
6.5
6.5
7.0
7.0
6.9
7.1
7.1
6.9
7.0
7.1
6.9
7.0
7.1
7.3
7.3*
7.2
7.4
7.3
7.2
7.3
7.3
7.2
7.3
7.3
7.8
7.6*
7.5
7.6
7.6
7.4
7.5
7.6
7.4
7.6
7.6
8.0
7.9*
7.8
7.9
7.9
7.7
7.9
7.9
7.8
7.9
7.9
8.6*
8.5*
8.3
8.3
8.3
8.3
8.3
8.3
8.3
8.3
8.3
8.9*
8.6*
8.4
8.4
8.3
8:.4
8.4
8.3
8.4
8.4
8.3
* Precipitate.
tained media, experience in this laboratory has not borne out these
contentions. In the course of the present work it hasahnost
invariably been found that Ph determinations on a given medium
distributed in different tubes check closely. Consequently this
factor has at no time been seriously considered as even partially
contributory to the reaction changes encountered.
It has been emphasized that in the very large majority of cases
the reaction change was in the direction of an acidity increase
HTDBOOEN-ION CONCENTRATION OF BROTH MEDIA
155
and further that the degree of variation upon standing was usu-
ally as great as upon autoclaving. In view of those findings the
possibility of an absorption of sufficient COi from the atmosphere
to account for the changes noted was considered. Experiments
II and III were carried out to decide this point.
TABLES
Experiment 7. Changes in reaction upon autoclaving and standing. (Beef extract
hroth)
Composition :
Distilled water 1000 cc.
Liebig's beef extract 3 grams
Peptone (Parke, Davis A Co.) 10 grams
NaCl 5 grams
BBTOBB
▲OTO-
AVTBB
▲OTO-
CLAYIKO
BOOM TBMFBBATUBB
AFTSB DATS
ioboh:
HT AfTKBDATi
niOUBATOB ATTBB DATB
ctJLrma
2
7
14
2
7
14
2
7
14
4.8*
4.8*
4.8
4.8
5.0
4.8
4.8
5.0
4.8
4.8
4.9
6.0*
5.0*
5.1
5.2
5.1
5.1
5.2
5.1
5.1
5.2
5.2
5.6
5.6
5.6
5.6
5.5
5.6
5.6
5.5
5.6
5.5
5.5
5.8
5.9
5.9
5.8
5.8
5.9
5.8
5.8
6.1
6.2 '
6.1
6.0
6.4
6.1
6.0
6.0
6.5
6.5
6.5
6.3
6.4
6.5
6.3
6.4
6.5
6.9
7.0
7.0
7.0
6.9
7.0
7.0
6.9
7.0
6.9
7.3
7.3
7.2
7.2
7.2
7.2
7.2
7.2
7.3
7.2
7.2
7.8
7.8
7.6
7.4
7.4
7.6
7.4
7.4
7.6
7.5
7.4
8.1
8.0
8.0
7.9
7.8
8.0
7.9
7.8
7.9
7.9
7.9
8.6
8.4*
8.2
8.2
8.0
8.2
8.1
8.0
8.2
8.0
9.0
8.8*
8.3
8.2
8.1
8.3
8.2
8.2
8.4
8.3
* Precipitate.
Experiment II. The effect of exposure in an atmosphere of 00%
upon the reaction of broth
Beef infusion broth, prepared and adjusted as outlined in the
preceding experiment, was tubed, autoclaved, and treated as
follows: (1) Control-beginning. (2) Exposed twenty-four hours
in plugged tubes to an atmosphere of CO2. (3) Control after
twenty-four hours.
The results shown in table 6 indicate that direct exposure of
broth to COs causes very decided increases in acidity, the amount
of increase becoming greater as the alkalinity of the broth
166
LAX7RENCE F. FOSTER AND SAMUEL B. RANDALL
increases. That such a condition is abnormal is, of course, quite
obvious, but the experiment serves to indicate that COj may not
be ruled out as a factor in causing acidity increases in media upon
standing.
TABLE 6
Experiment II
Pb after auioclaving
Ph after exposure to COt for 24 hours
Pb (control) after 24 hours
5.3
5.3
5.3
5.6
5.4
5.6
5.
5.5
5.8
86
.ob.2|6.5
5.65.75.8
6.06.26.5
7.17.4
5.96.116
7.17.4
7.6
2
7.6
7
6
98
26
7.98
.3
3
384
6.4
8.4
Experiment III. The effect of exposure of sterilized broth to an
atmosphere free from COi
Tubes of the medium prepared in the preceding experiment were
autoclaved and treated as follows: (1) Control, allowed to stand
at room temperature. (2) Placed in a COr-free atmosphere.
Ph readings were made at the outset, after seven days, and after
fourteen days. To obtain atmosphere free from CO2 air was
drawn through a train of Woulff bottles containing concentrated
NaOH, 20 per cent Ba(0H)2, and CaCU into a large Navy jar
containing the tubes of media.
By inspecting table 7, it will be noted at once that practically
the same changes in Ph occurred in both sets of tubes. This
would seem to dispose of atmospheric CO2 as a factor operative in
causing the increases in acidity so frequently noted in the previ-
ous experiments.
TABLE 7
Experiment III
Ph after autoclaving
Pb after 7 days in atmosphere
Ph after 7 days in COj-f ree air ... .
Pr after 14 days in atmosphere
Ph after 14 days in COs-free air . . .
5.1
5.2
5.1
5.0
5.0
5.3
5.5
5.4
5.4
5.4
5.8
5.8
5
5.8
5.7
86
6.16
6.16
06
6.16
6.0j6
36
46
6
6
46 6
36.6
7.0
7.1
7.1
7.2
7.4
7
416.67.07.3
7.3
6.9
47
8.5
8.3
7.6
7.8
8
7.88.08.418
7.9
8.0
8.0
8.08.318
8.3
8.7
8.6
6
6
8.4
Assuming that the external factors of glassware aa&d atmospheric
C0» are not sources of change in reaction of broth media it will
be necessary next to examine the internal factors, namely, the
possibility of chemical changes in the medium itself. The organic
HYDBOGBN-ION CONCENTRATION OF BROTH MEDIA 167
components of broth media are in themselves complex compoimds,
which in some cases, are relatively unstable and reactive. It has
long been noted that in the preparation of media precipitates
occur when certain amounts of acid or base are added. In some
cases precipitation occurs as soon as the acid or base is added, in
other cases autoclaving seems to be required to bring down the
material. Kligler (1917) has established certain zones of hydro-
gen-ion concentration for aqueous solutions of peptone within
which precipitation occurs, and has investigated the nature of
the precipitates themselves. In the acid range he beUeves that
the material arises largely from protein substances as upon redis-
solviQg it gives reactions of proteoses and peptones, whereas in
the alkaline range it is made up largely of phosphates. It is
rather significant that the ranges of Ph in which we find the great-
est change in reaction upon sterilization and standing are those
within which precipitation is apt to occur during adjustment of
the media.
The r61e of peptone in media is two-fold. It furnishes nitrog-
enous food in the form of protein split products (peptones, pro-
teoses, peptides, amino acids) and through its property of combin-
ing with acids and bases acts as a bufifer. According to Rettger,
Berman, and Sturges (1916) and Davis (1917) American peptones
are lower in albumoses and higher in amino acids than Witte's,
some of those examined by the latter having two or three times
the content of amino acids.
It seems quite certain that during autoclaving of culture media
the higher nitrogenous complexes are hydrolyzed to lower split
products. This would be particularly true in media adjusted in
the acid or alkaline ranges, inasmuch as acids and bases act as
positive catalyzers of a protein hydrolysis. During the splitting
of a protein by hydrolysis there occxir marked changes in the
acidity or alkalinity of the solution in which the change takes
place. Sorensen (1912) has reported an experiment in which the
digestion of peptone by trypsin was carried out, measurements of
hydrogen-ion concentration and determinations of the increase
in formol-titrating material being made at intervals. The in-
crease in hydrogen-ion concentration did not stand in relation to
158 LAURENCE F. FOSTER AND aAMUEL B. RANDALL
the increase in COOH groups and Sorensen concluded that the
increased base-binding power was due to the formation of pep-
tides. T. B. Robertson (1918) has studied rather intensively
the changes in hydrogen-ion concentration which take place ding-
ing the hydrolysis of certain proteins and concludes that the power
to bind acids and bases resides in the -COHN- groups, inasmuch
as the protein molecule does not contain a suiO&cient number of
terminal -COOH and -NHj groups to account for its high combin*
ing capacity for acids and alkaUes. While bound up in the pro-
tein molecule these groups do not assist in the neutralization of
acids and bases but during hydrolysis the bonds are opened and
the binding capacity is increased.
Itano (1916a) has reported an increase in formol-titrating nitro-
gen in media upon steriUzation and has apparently shown that
at least a rough proportionality exists between the change in Pb
(increase) and the increase in amino acids as measured by the
method of Sorensen.
With the view to ascertaining whether or not the changes in Ps
found in the experiments described could be correlated with an
increase in COOH groups produced through hydrolysis of the
peptone or protein of the broth the following experiments were
carried out:
Experiment IV. The relationship between Pn changes in media and
changes in formol4itraiing nitrogen
Five lots of beef infusion broth were adjusted to Ph values
ranging from 5.2 to 9.2 and each lot distributed in three 30 cc.
portions. The Ph and formol number were determined: (1)
before autoclaving; (2) after autoclaving; (3) after seven days
standmg at room temperature.
Technic of formol titration^ Kendall, Day, and Walker (1913):
Five cubic centimeters of the broth was diluted with 50 cc. of dis-
tilled water and 1 cc. of phenolphthalein (1 per cent alcoholic
solution) was added. The material was titrated to a faint pink
with n/20 NaOH or n/20 HCl. Five cubic centimeters of
neutral formalin were then added and the mixture allowed to
stand for thirty minutes after which it was again titrated with
HTDBOGEN-ION CONCENTRATION OF BBOTH BOSDIA
159
n/20 NaOH. From the last figure, the fonnol number was
obtamed.
Formol number {F. N.): Milligrams of formol-titrating N per
100 cc. of culture.
The results of the experiment are contained in the following
table :
TABLES
Experiment IV
BSFOBB ATTTOCLArnro
AVTBB AXnTOCLATZHO
AITBB BBTBN DATB
Ph
P.N.
Ph
F.N.
Ph
P.N.
6.2
40.4
5.3
44.8
6.3
44.8
6.2
42.0
6.3
47.6
6.3
47.6
7.2
42.0
7.2
47.6
7.2
47.6
8.2
43.4
8.0
44.8
8.0
44.8
9.2
43.4
8.8
43.4
8.8
47.6
As a result of autoclaving, slight increases in formol-titrating
nitrogen are manifest in every lot of broth excepting that adjusted
to Ph 9.2 which was the only flask to show any appreciable change
in Ph. The greatest increases in formol niunber are seen in the
lots which showed little or no reaction change. No change in
formol-titrating nitrogen occurs during the first seven days fol-
lowing autoclaving except in the 9.2 lot. Here a small increase
occurred. From the results of this one experiment it must be
concluded that changes in the Ph of broth as a result of autoclav-
ing and standing bear no relationship to changes in formol-titrating
nitrogen. The results are at variance with those reported by
Itano (1916a) in which decreases in the hydrogen-ion concentra-
tion of broth upon autoclaving appeared to be roughly correlated
with increases in formol-titratiug nitrogen. It perhaps should be
noted that fewer changes in Ph were recorded in experiment IV
than were apparent in the earlier experiments.
At present, the most logical explanation of acidity increase
noted in the various experiments would rest upon the observation
of Robertson that as the hydrolysis of a' protein proceeds the base-
binding capacity of the material increases through the opening
up of the -COHN- group of the protein molecule.
160 LATJBENCE F. FOSTER AND SAMUEL B. RANDALL
SUMMARY AND CONCLUSIONS
1. Broth (beef infusion, beef extract, ''bacto-beef") adjusted
to Pb values ranging from 5.0 to 9.0 undergoes a change in hydro-
gen-ion concentration upon autoclaving. This change is most
marked in media adjusted in the alkaline range (7.8-9.0), less
great in the acid range (5.0-6.2), and is usually inappreciable in
the neutral range (6.&-7.4). The maximum change is about 0.4
Ph and in the majority of cases is not over 0.2 Ph.
2. The change is usually an increased acidity (decrease in Ph).
Decreases in acidity have been observed in a few instances but
these are exceptional.
3. In media of the same composition the reaction changes are
not necessarily imiform in different experiments.
4. Autoclaved broth imdergoes changes in hydrogen-ion con-
centration upon standing; the degree of change is not influenced
by the environmental temperature within the limits, 10°C. (ice
chest) and 37*^0. (incubator).
5. The reaction changes upon standing, as in the case of auto-
claving, are most noticeable in the alkaline range, less marked in
the acid range, and least in the neutral range. Neutral media
usually do not change at all upon standing.
6. The change upon standing is ahnost invariably in the direc-
tion of an increase in acidity.
7. Broth adjusted to various Ph levels ranging from 5.0 to 9.0
and exposed in tubes plugged with cotton to an atmosphere of
CO2 for twenty-four hours shows marked alterations in reaction.
The change is always an increase in acidity, as would be expected.
The greatest change occurs in the alkaline range.
8. Upon allowing broth adjusted to various Ph levels to stand
in a COr-free atmosphere the same reaction changes were noted
as in duplicate lots of broth allowed to stand in the air of the lab-
oratory. The increases in acidity exhibited by broth upon stand-
ing do not seem to be due to an absorption of atmospheric COj.
9. Reaction changes in media of Ph 5.2 to 9.2 do not appear to
stand in relation to changes in formol-titrating nitrogen.
10. The possibility of an increase in acidity of broth through
the opening up of -COHN- groups during hydrolysis of the pro-
tein constituents suggested by Robertson remains a plausible one.
THE RELATION OF HYDROGEN-ION CONCENTRATION
TO THE GROWTH, VIABILITY, AND FERMENTATIVE
ACTIVITY OF STREPTOCOCCUS HEMOLYTICUS
LAURENCE F. FOSTER
From the Department of Pathology and Bacteriology, University of California
Received for publication August 15, 1020
I. THE FINAL HYDROGEN-ION CONCENTRATION PRODUCED BY
STREPTOCOCCUS HEMOLYTICUS IN BROTH CONTAINING
VARIOUS FERMENTABLE SUBSTANCES
In 1912, Michaelis and Marcora (1912) working with a cul-
ture of BacL coll in lactose broth were able to show by means of
accurate electrometric measurements^ that this organism carries
its fermentation of the sugar to a definite level of hydrogen-ion
concentration and then ceases its activity. This point is reached
regardless of the initial reaction of the medium and cdn be
described as a physiological constant for the particular organism
used. This finding was confirmed three years later by W. M. Clark
(1915b) ^ who pointed out that the final hydrogen-ion concentration
established as a physiological constant by Michaelis and Marcora
for a single strain of Bact colt applied to other strains as well.
That the hydrogen-ion concentration of the culture, rather than
the total acid produced, is the factor limiting activity of the
organism seemed evident from the work of Clark. The useful-
ness of this so-called physiological constant appeared later as
the result of the researches of Clark and Lubs (1915) who sug-
gested a method of differentiating the bacteria of the colon-
aerogenes group by means of a correlation with gas formation of
the final hydrogen-ion concentration produced in glucose broth.
In this work was laid the experimental foundation of the methyl
^ Bibliography is found at the end of the third article in this series, p. 231.
161
162 LAUBENCE F. POSTER
red test in use at the present time. Ayers (1916) in an investi-
gation of the final hydrogen-ion concentration in some 200 cul-
tures of streptococci was able to demonstrate a somewhat higher
acidity^ in cultures of the non-pathogenic than in those of patho-
genic species grown upon glucose broth. Later work by Ayers,
Johnson, and Davis (1918), as well as by Avery and Cullen
(1919a), has led to the suggestion of a rapid presumptive test for
the differentiation of bovine and human streptococci based
upon differences in the final hydrogen-ion concentration pro-
duced in glucose broth. However, as Brown (1920) has pointed
out, no single procedure can perhaps serve to differentiate the
two varieties absolutely inasmuch as atypical strains are some-
what frequent. Cullen and Chesney (1918), Jones (1920,
1920a), Avery and Cullen (1919b), and Lord and Nye (1919),
working with pneumococci of the various types in glucose broth,
have foimd a final hydrogen-ion concentration that is in close
agreement with the constant established for the streptococci.
This value appears to be the same in all types irrespective of
immunological character. The works of Fred and Loomis (1917)
upon alfalfa bacteria, of Bimker (1916-1917, 1919) and Davis
(1918) upon CorynebacL diphtheriae, of Itano (1916a, 1916b)
upon B. svbtiUs and certain streptococci, of Cole and Onslow
(1916) upon the typhoid group, of Clark (1917) upon Lacto-
bacillus bulgaricus, of Waksman and Joffe (1920) upon Actino-
mycetes, of Ayers and Rupp (1918) upon members of the alkali-
forming group, of Wolf and Harris (1917a, 1917b) upon Clostridium
welchii and C. sporogenes, of Gillespie (1916, 1918) on soil organ-
isms, and of Cohen and Clark (1918) upon various organisms
are indicative of an attempt on the part of present-day workers
to gain a more accurate knowledge of the metabolic activities of
micro-organisms through the measurement of changes in the
hydrogen-ion concentration brought about in culture media.
Determinations of titratable acidity and ammonia, according to
Kligler (1916), give an indication of the extent of carbohydrate
* The terms acid and acidity in the present paper refer to true acidity as ex-
pressed in terms of Ph, except when the reference is specifically to titratable
<icid or acidity.
STREPTOCOCCUS HEMOLYTICUS 16S
and protein splitting by bacteria, whereas measurement of the
hydrogen-ion concentration in cultures measures the resultant of
both these actions.
It seemed advisable at the beginning of the present phase of the
mvestigation to obtain information as to the level of final acidity
produced by Streptococcus hemolyticus in broth media contain-
ing a number of the conmion fermentable substances employed
in the bacteriological laboratory. Accordingly experiment I was
carried out.
Methods and technic
CvUure. All of the work to be described in the present paper
was carried out on one pure strain of Streptococcus hemolyticus^
This strain, designated as the ''H/' was originally isolated from
the limg in a fatal case of bronchopneumonia compUcated by
endocarditisi and corresponds to culture nmnber 136 in the series
obtained during the investigation of pneumonia in military
camps by the Rockefeller Commission. The "H" strain was
of high virulence, owing to repeated passage through rabbits
in an investigation of experimental streptococcus empyema, and
the pleural fluids of such animals, taken at autopsy with sterile
precautions (Gay and Stone, 1920), were foimd to serve as an
excellent source of culture material. All pleural fluids were
stored in the ice chest as the contained organisms have been
found to remain viable under such conditions for a number of
weeks. A transplant of 0.2 cc. of the pleuritic exudate was made
into 5 cc. of 1 per cent glucose broth and the tube incubated for
eighteen hours. As this first generation culture invariably con-
tained a considerable amoimt of cellular debris, a second sub-
culture was prepared in a similar manner. This second genera-
tion served as a source of inoculum in practically all of the
experiments to be described. The eighteen-hour incubation
period was chosen inasmuch as preliminary tests had shown
that rapid growth nearly always obtained in sub-cultures pre-
pared from a parent culture of this age.
Culture media. Beef infusion broth served as the basis of
the media employed throughout the work as it is a generally
164 LAURENCE F. POSTER
recognized fact that the pathogenic streptococci develop more
luxuriant growth upon this medium than upon broth prepared
from beef extract. In some of the experiments "Bacto-beef"
(Digestive Ferments Company) was employed instead of beef
juice as a base. Growth upon this medium was found to be as
luxuriant as upon the usual beef infusion broth. The broth
contained 1 per cent peptone (Difco or Parke, Davis, and Com-
pany), and 0.5 per cent NaCl. Adjustment to the desired Pa
was made according to the method previously described. The
limits of Ph, 7.0-7.6, were found to favor luxuriant growth of the
organism. The prepared broth was always incubated for
twenty-f oiu" hours previous to inoculation to insure its sterility.
Ph determinations .* These were made by the method described
in a former paper using 1 cc. of culture plus 4 cc. of freshly boiled
and cooled distilled water. A tube containing the same mate-
rials without indicator was alwajrs used by the method of super-
position to eliminate as far as possible factors of color and
tm-bidity. Determinations carried out in this way permitted
readings to within 0.05 Ph in nearly all cases.
Experiment I. The final hydrogen4on concentration of Strepto-
coccus hemolyticus in broth containing various fermentable
substances commonly employed in the bacteriological laboratory;
also an attempt to investigate the possibility of an experimental
adaptation to a given sugar medium, through repealed transplant
talion.
Inoculation of 0.4 cc. of an eighteen-hour, second-generation
culture was made into 10 cc. lots of beef infusion broth contain-
ing the given fermentable material in 1 per cent concentration.
Transplants from each tube were made, into sterile lots of
media of corresponding composition after twenty-foiu' hours
incubation. In this manner five generations were carried.
Althougih the "H" strain had previously been found to produce
the characteristic final hydrogen-ion concentration quite con-
' The 83rmbol ?■ of Sdrensen is used throughout to designate the hydrogen
ion concentration.
STREPTOCOCCUS HBMOLYTICUS 166
sistently within the first twenty-four hours following incubation,
nevertheless in this experiment it was decided to allow a f orty-
eight-hom* incubation period before making Pb determinations
to insure the completion of the fermentation.
Reference to table 1 shows that of the several groups of sub-
stances tried only the hexoses and disaccharides were fermented
by the streptococcus. A wide variation in final Pr is noted.
No explanation of these differences is attempted at the present
time. Clark (1916b) working with BacL coli, reports lower
Pr levels in glucose broth than in lactose broth, while Jones (1920)
has described a similar phenomenon in cultures of Streptococcus
hemolyticus and pneumococci. Similar results are evident in the
present experiment. An interesting fact brought out is that
plain broth shows an increase in hydrogen-ion concentration.
It is also to be noted that in no case in which fermentation did
occur was the characteristic final Pb reached in the first genera-
tion. This would seem to indicate that in procedures for differ-
entiation based upon final Pr levels, several transfers of the cul-
tures should be made upon the same medium before conclusions
as to the final hydrogen-ion concentration are drawn. In nearly
all cases the characteristic final value was reached after one
transfer.
The fact that plain broth shows an increase in hydrogen-ion
concentration when inoculated with the streptococcus would
seem to indicate that sufficient muscle sugar is present to permit
fermentation to the Pr level indicated. To decide this point,
a lot of infusion broth was inoculated with Bad. coli to ferment
out any free sugar, after which it was filtered, adjusted, and
sterilized. Upon inoculation with a culture of Streptococcus
hemolyticus it was found that the final Pb was the same as that
noted in the experiment just described. In this case the initial
Pr of the broth was slightly lower, namely, 7.36. A similar
result was experienced when sugar-free, bacto-beef broth was
tried. In their studies of the metabolism of Streptococcus pyo-
genes and other organisms Kendall and his associates (1912c,
1912a) found increases in titratable acidity in plain broth cul-
tures but carried out no determinations of hydrogen-ion concen-
166
LAURENCE F. FOSTER
tration. According to these investigators, the phenomenon
may be explained on the basis of a selective action of the organ-
ism in question upon that portion of Witte's peptone which Pick
(1898) has shown contains a relatively large fraction of a sub-
TABLEl
Expcnvncnt I
•
Ph
(ixitial)
OBNIKATIOX
irUllBKX
CASBOBTDHATS
1
2
8
4
6
1
None
f
7.50
6.70
6.70
6.70
+ +
6.70
2
Glucose
7.60 1
«
6.10
+++
4.80
+++
4.85
3
Fructose
7.60 1
5.30
•
+++
6.10
5.10
6.10
6.05
4
Mannose
7.60 1
6.40
5.20
5.26
5.20
5.20
5
Galactose
7.50 j
+++
6.60
+++
5.40
+++
6.40
5.40
5.30
6
Xylose
7.50 1
6.60
6.70
•
6.70
++
6.70
7
Sucrose
7.50 1
+++
6.35
5.20
6.10
6.16
5.10
8
Lactose
7.60 1
+++
6.60
+++
6.50
+++
6.40
5.40
6.40
9
Maltose
7.60 1
5.40
+++
6.30
+++
5.15
+++
6.10
+++
6.15
10
Inulin
7.50 1
6.60
6.60
6.70
6.70
6.70
11
Glycerol
7.50 1
6.60
+-f
6.70
6.70
6.70
6.60
12
Mannite
7.50" 1
6.60
6.60
6.70
4"f
6.70
6.70
STREPTOCOCCUS HEMOLYTICUS 167
stance reacting typically like a carbohydrate. Although the
peptone used in the present experiments was not Witte's it
seems entirely possible that American peptones such as the one
used here (Parke, Davis and Company) might contain a similar
carbohydrate substance. The fact that a definite increase in
hydrogen-ion concentration has always been observed in the
sugar-free broth employed surely would lend support to such a
supposition.
n. THE INFLUENCE OF VARYING AMOUNTS OF GLUCOSE AND BUFFER
SALra UPON THE FINAL HYDROGEN-ION CONCENTRATION
OF STREPTOCOCCUS HEMOLYTICUS
It has long been recognized that the acidity produced by cer-
tain organisms in culture media results from the elaboration of
acid substances through a fermentation of material, mainly of
carbohydrate nature. With the introduction of accurate meth-
ods of evaluating the acidity produced in bacterial fermentations
through a determination of the concentration of the hydrogen-
ions, it became necessary to investigate the factors which may be
operative in the production of a limiting or final hydrogen-ion
concentration. Thus, Clark and Lubs (1915) in their work on
the differentiation of the bacteria of the colon-aerogenes family,
used media containing amounts of glucose varying from 0 to 0.5
per cent and demonstrated that by increasing the concentration
of the sugar up to a certain point a greater final acidity resulted.
If sufficient sugar was present for the limiting acidity to be pro-
duced, no alkaline reversion occurred in their cultures. Browne
(1914), using cultures of BacL coli in lactose-broth, foimd that
acid production was less marked in media containing under 1
per cent sugar but that the use of amoimts over 1 per cent resulted
in no increase. Browne titrated his cultures with n/20 NaOH
but failed to make determinations of the final hydrogen-ion con-
centration. Avery and Cullen (1919b) foimd that pneumococci
were able to reduce the Ph of glucose-broth from 7.50 to 5.10
provided 0.4 per cent of the sugar was present. Increasing
concentrations of glucose up to 4 per cent showed no change in
JOXTBlfAL OP BACrXBIOLOOT, VOX.. ▼!, NO. 2
168 LAURENCE F. FOSTER
final Ph. In the work of the same mvestigators (1919a) upon
Streptococci of human and bovine origin it was shown that the
same final Ph is reached in broth containing 0.5, 1, or 1.5 per
cent of glucose. Sekiguchi (1917) foimd the highest production
of acid by streptococci with 0.5 to 2 per cent of glucose. Amounts
of sugar over 5 per cent caused reduction in acid formation
though growth was not hindered. H. Jones (1920) has recently
foimd that a nmnber of organisms are able to produce their
characteristic final hydrogen-ion concentration provided 0.2
per cent or more glucose be present in the medium. He failed
to state the initial Ph of the medium which factor has an impor-
tant bearing on the minimum concentration of a sugar needed
for production of the final acidity by any given organism. The
effect of varying amounts of xylose upon the production of
volatile acid by xylose fermenting organisms has been studied
by Fred, Peterson, and Davenport (1919) who foimd that 2
per cent of the sugar gave the maximum production of acid.
The presence in the culture medium of substances which through
their buffer effect have the power of neutralizing some of the
acid as it is produced is of interest and importance in this
connection.
Henderson and Webster (1907) in 1907 suggested the use of
phosphates to preserve neutrality in media during the growth of
acid- or alkali-forming organisms, and Clark (1915a) has more
recently pointed out in considerable detail the great importance
of properly buffered media in bacteriological work. Using lots
of broth containing different buffers, Clark (1915b) showed that
Bact. coli produces somewhat lower levels of Pr in the more
highly buffered media.
Kligler (1916) working with cultures of Bact. doacae, Bact.
aerogenes, and Bact. coli studied the final Ph as influenced by
different concentrations of peptone, NasHP04, and glucose.
The concentration of peptone was foimd to influence the utiliza-
tion of glucose by the organisms in such a way as to result in a
lower final Pb with a low peptone concentration in the medium.
In some cases the presence of buffer allowed all of the sugar to
be used up with a subsequent rise of Ph thus indicating that an
STREPTOCOCCUS HEMOLTTICUS 169
alkaline phase had been mitiated' through the splittmg of pep-
tone. The presence of buffer, accordmg to Kligler, keeps the
hydrogen-ion concentration below the lethal point and thus
allows the organism to continue its activity over a longer period.
As a result of this regulatory power the amoimt of glucose which
may be used will vary, within limits, with the relative amount
of buffer material present. Bronfenhrenner and Schlesinger
(1918) working with BacL coli have tried similar experiments by
noting the effects of varying amoimts of lactose, peptone, and
buffer salts upon gas formation and final Ph. After trying some
294 combinations, these investigators concluded that with any
given concentration of carbohydrate the amoimt of free acid
depends upon the concentration of buffer in the medium. As
the amount of peptone increases, the per cent of sugar attacked
is smaller and lower hydrogen-ion concentrations result. The
necessity of carefully controlling the composition of media
employed in fermentation experiments is emphasized.
From the foregoing review the following facts seem to have
been well established:
1. In any given medium a definite concentration of sugar
must be present if the organism in question is to produce its
characteristic final hydrogen-ion concentration.
2. This minimum concentration of sugar wiU depend upon the
concentration of buffer salts present, as well as upon the concen-
tration of peptone in the medium.
3. In making estimations of this minimum concentration of
sugar required for the production of the final hydrogen-ion con-
centration the quantity of buffer should be known as well as the
initial Ph of the culture medium.
4. With increasing concentrations of buffer salts there is an
increased neutralizing power which delays the production of the
final acidity level, thus allowing the organism more time for
fermentation.
170
LAURENCE F. F08TEB
Experiment II* The effect of varying concentratiofia of glucose
upon the final hydrogevr4on concentration of Streptococcus
hemolytums
Ten cubic centimeter amounts of beef infusion broth contain-
ing concentrations of glucose varying from 0.10 to 1 per cent
were inoculated with 0.4 cc. of an eighteen-hour culture of
Streptococcus hemolyticus in 1 per cent glucose broth and incu-
bated for three days to ins\u*e the completion of the fermenta-
tion. Ph readings were then made. The results are shown in
table 2.
TABLE 2
Experiment II
1
2
iiaonjM
Beef infusion broth
Beef infusion broth (sugar free)
Pa
(ikitial)
6.90
7.35
Ph (fxxal; in glqcosb (pbb cbnt)
5.60
16.706.05
0.1
OJ
0.S
5.005
5.605.10
0^
105.05
5.15
IjO
5.10
5.00
In (1) which was adjusted to an initial Ph of 6.9 the final Ph
was attained in a glucose concentration of 0.2 per cent, whereas
in (2) which was adjusted to an initial Ph of 7.35 the final value
was not shown in the 0.2 per cent glucose but did appear in the
0.3 per cent tube. As would be expected the minimum concen-
tration of glucose needed to give the characteristic final Ph is
dependent upon the initial Ph of the broth. Amounts of glucose
\ over this minimum concentration have no further effect upon
the level of the final hydrogen-ion concentration.
Experiment III. The influence of a buffer salt upon the final
hydrogen-ion concentration of Streptococcus hemolyticus in
broth containing varying concentrations of glucose
Bacto beef broth was adjusted and distributed in twelve
lots in flasks. After autoclaving, the requisite amounts of
glucose and di-potassium phosphate, K2HPO4, were added in
the form of sterile 10 per cent solutions bringing the total volume
of material in each flask to 25 cc. Following twenty-four
STREPTOCOCCUS HBMOLYTICUS
171
hours incubation to insure sterility each flask was inoculated
with 1.25 cc. of an active twenty-two-hour culttire. Determi-
nations of Ph and '^reaction" were made after an incubation
period of four days. The "reaction" was determined by titrat-
ing 5 cc. of culture with n/50 NaOH, using neutral red as an
indicator and calculating the number of cubic centimeters of n/1
NaOH needed to neutralize the acid in 100 cc. of culture. Tibbie
3 contains the results of the experiment.
TABLES
Experiment III
irtTMBBB
OliUCOBB
KtHFOi
Pb (nrxTZAL)
PH'CnifAL)
••■BAcnow"*
per emU
ptr ufU
1
0.3
0
6.go
6.10
0.72
2
0.3
0.2
6.90
5.06
1.41
3
0.3
0.5
7.20
5.20
2.13
4
0.3
1.0
7.20
6.30
2.43
5
0.5
0
6.75
5.20
0.70
6
0.6
0.2
6.70
5.00
1.54
7
0.5
0.5
7.20
6.05
2.18
8
0.5
1.0
7.20
6.20
2.16
9
1.0
0
6.90
6.15
0.81
10
1.0
0.2
6.90
6.00
1.56
11
1.0
0.5
7.20
4.90
3.36
12
1.0
1.0
7.20
5.20
4.73
* Cubic centimeters of n/1 NaOH required to neutralize 100 cc. of culture.
As will be seen by referring to table 3 the final Pb characteris-
tic of the streptococcus is not reached in the media containing
0.3 per cent and 0.5 per cent glucose plus 1 per cent phosphate
(numbers 4 and 8 in table). These concentrations of glucose
are apparently not sufficiently great to allow the formation of
enough acid to bring the culture to the characteristic level,
whereas in the case of the 1 per cent glucose plus 1 per cent
phosphate a characteristic final Pr is reached. Correlated with
these facts are the differences in titratable acid as shown in the
last column of the above table. It is an interesting fact that
virtually the same final Pb is shown in the greatei* number of the
172
LAX7RENCE F. FOSTER
above cases and yet the total quantities of actual acid, as shown
by titration, are widely di£ferent. No better illustration of the
eflSciency of a buffer could be offered. Very obviously the utili-
zation of glucose is here closely related to the concentration of
buffer present. A further fact, of interest and importance, is
that the final hydrogen-ion concentration rather than the total
acid produced is the factor which limits the fermentative activi-
ties of the organism.
Experiment IV. The influence of horse serum in glvcose broth
upon the final Ph of Streptococcus hemolyticus
Ten cubic centimeter lots of beef infusion broth (sugar-free)
containing varying amoimts of glucose and horse serum were
prepared and inoculated with 0.4 cc. of an eighteen-hour culture.
After an incubation of three days Pb determinations were made.
The results of (2) in experiment II are inserted in table 4 for
purposes of comparison.
TABLE 4
Experiment IV
NUICBBB
HOBSB-BBBUIC
Pb (iNznAL)
Pb (fINAL) IN OLUOOSB (PBB CBBT)
0
0.1
0.2
O.S
0.6
1.0
1
2
2 (exp. II)
Pir cent
5.0
10.0
None
7.40
7.60
7.35
6.80
6.80
6.70
6.70
6.60
6.05
6.10
5.90
5.60
5.05
5.15
5.10
5.00
5.00
5.15
5.00
5.10
5.00
As in experiment II it is to be noted that 0.3 per cent glucose
is the minimum concentration which will permit the attainment
of the characteristic final Pb. The greatest differences in Pb
between the media containing horse serum and (2) of experi-
ment II are seen in the tubes containing 0.1 per cent and 0.2
per cent glucose. It seems possible that in these cases the
horse serum prevents the increase in acidity of the medium to a
small extent through its action as a buffer. In those tubes con-
taining sufiicient glucose for the production of the final Pb char-
acteristic of the organism no differences in the level of this final
value are seen. That we do have a decided difference in the
rates of acid production will be shown in a later experiment.
SISEFTOCOCCXJS HEMOLYTICUS
173
ExperimerU V. The buffer action of horse serum in hroth
To investigate further the buffer effect of horse serum titra-
tion curves of broth containing 1 per cent glucose, 1 per cent
glucose plus 5 per cent horse serum, and 1 per cent glucose plus
<>^l'Ht^'^^
%> hlCCUCH^
FlO. 1. EXPERUISNT V
10 per cent horse serum were plotted after the following proce-
dture had been carried out: To 10 cc. portions of the three types
of broth mentioned above, amoimts of n/50 acetic acid varjring
from 1 to 12 cc. were added and the Ph taken. The curves were
174 LAUBENCE F. FOSTEB
ft
plotted using the cubic centimeter of acid as abscissae and the
Ph readings as ordinates. Reference to the curves (fig. 1) will
show that horse serum in these concentrations exerts a slight
but distinct buffer effect. The 10 per cent series does not show
a much greater buff^ action than the 5 per cent series however,
and the effect in no case is anything like that noted in the case
of K2HPO4 (experiment III).
ni. THE RATE OF ACIDITY FORMATION ENT CULTURES OF STREPTO-
COCCUS HEMOLTTICUS
•
Considerable work by a number of investigators has demon-
strated that the life cycle of a given organism, as measured by
the number of viable cells present at various intervals following
inoculation, may be separated into very definite periods. Thus,
Chesney (1916) has suggested a division into foiu* phases: (1)
latent period or lag, (2) maximiun growth period, (3) stationary
period, (4) period of decline.
No sharp dividing lines may be drawn between the periods,
and their duration will vary in the case of the same organism
with such factors as the amount of inoculum, age of parent
culture, and initial reaction of the medium. Buchanan (1918)
described seven periods in the life of an organism: (1) initial
stationary phase; (2) lag phase when growth proceeds at a slowly
accelerating rate; (3) maximiun or logarithmic period in which
the rate of increase in numbers is constant; (4) period of nega-
tive growth acceleration, the organisms are increasing at a
decreasing rate; (5) maximum stationary period; no increase in
numbers; (6) period of accelerated death, decrease in taking
place at an increasing rate; (7) logarithmic death phase; death is
occurring at a constant rate.
With the development of procedures for the mathematical
analysis of the several phases (Buchner, Longard, and Riedlin
(1887), Buchanan (1918), Slator (1917), Ledingham and Penfold
(1914) has come the possibility of more definite knowledge con-
cerning the growth activities of organisms.
BTRBPTOCOCCUS HBMOLYTICUS 176
A search through the literature reveals the fact that the
latent period or lag phase has received the bulk of the attention
of workers in Una field. Mtlller (1896) perhaps was the first to
recognize the phenomenon while working with cultures of Bad.
typhosum at temperattires simulating febrile conditions. The
duration of lag was found by him to vary with the age of the
culture used for seeding, being shorter for young than for older
cultures. He believed the phenomenon to be the result of an
alteration of the cells sustained upon transplantation to a new
medium, the duration of lag representing the time required for
the organisms to recover from the injury. Rahn (1906), working
with Pa. fluoreBcenBj studied the influence upon lag of the amount
of inoculum and concluded that the larger the niunber of organ-
isms used for seeding, the shorter the lag. Penfold (1914) later
demonstrated that this effect held, up to a certain limit, beyond
which an increase in the amount of inoculum exerted no influence
upon the duration of the lag period. In case of small inocula,
however, Penfold showed that a diminution in amount of seed
invariably caused a lengthening of lag. He found that older
cultures caused lengthening of lag only up to a certain point, for
example, a foiur-day culture gave the same diu^ation of lag as a
twelve-day cultture in the case of Bact. coli. Barber (1908)
working with single cells {Bad. coli) was the first to show that
under proper conditions lag may be eliminated. He used
rapidly dividing cells which were accustomed to the medium
employed and was able to find no evidence of inhibition upon
transplantation. This observation has received substantiation
at the hands of Penfold (1914), Chesney (1916), and Salter
(1919), all of whom worked with Bact. coli. Coplans (1909)
also states that with Bact. coK, there is ordinarily no absolute
lag upon transplantation to a favorable medium. New milk
ordinarily possesses inhibitory properties but this investigator
found that heating momentarily to lOO^'C. caused a disappear-
ance of this special inhibitory quality. Salter (1919) found also
that the age of the parent culture exerted a considerable influence
upon the diuration of lag, thus confirming the observations of
previous investigators. Lane-Claypon (1909) has studied the
176 LAT7BENCE F. FOSTER
•
rate of growth of organisms as affected by different temperatures^
and has demonstrated a conformity of her curves with the Van't
Hoff-Arrhenius law within certain limits.
The various other phases in the life of a culture have beea
investigated to a less extent but from the work of Buchanan
(1918) and Ledin^am and Penfold (1914) it seems probable
that growth is a discontinuous process in the sense that devdop-
ment of a given organism is dependent upon different laws in the
successive phases of the life of the cultm^e.
An illustrative ciuve follows:
U2I
(5)
ft)
(J) I
Fig. 2. Illxtbtrative Curve of Acid Formation bt Streptoooocus
HEIIOLTTICUB IN GlUGOBB BrOTH
(1) Initial stationary period.
(2) Lag period. Acid foimed at a slowly increasing rate.
(3) Maximum period. Acid formed at a constant, maximum rate; curve-
is an oblique, straight line.
(4) Period of negative acceleration. Acid formed at a decreasing rate.
(5) Maximum stationary period. Final Ph has been attained; curve is a
straight line parallel to the abscissa.
STREPTOCOCCUS HEMOLYTICUS 177
If broth containing glucose be inoculated with an actively
growing cultiure of Streptococcus hemolyticus and incubated,
there ensue changes in the hydrogen-ion concentration of the
medium culminating in the establishment of a limiting or final
reaction. A study of these changes, as measured at regular
intervals, indicates that the course is a perfectly definite one
capable of being separated into the following characteristic
phases: (1) Initial stationary period, no change in reaction;
(2) latent or lag period, acid formation at a slowly increasing
rate; (3) maximum period, acid formation at a constant rate;
curve an oblique straight line; (4) period of negative accel-
eration, acid formation at a decreasing rate; (5) maximum
stationary period, final Ph reached^ curve a straight line parallel
to the abscissa.
It will be noted that this sub-division of the course of reaction
change corresponds with Buchanan's life phases of a bacterial
culture based upon numerical determinations of viable organ-
isms, with the exception that his two final periods, representing
a decrease in number, cannot, of necessity, apply to an acid
curve such as is characteristic for the streptococcus. The work
of Cullen and Chesney (1918) on pnemnococci has shown a close
relationship between growth-rate and speed of acid production
in plain broth, and accordingly these observers have concluded
that acid formation is to be considered as ah active metaboUc
process, closely associated with the growth activities of the
organism. In examining the curves of Cullen and Chesney one
is struck by the close parallelism that exists between the various
phases in the life of the pneiunococcus, as measured by nmnbers
of viable cells on the one hand, and by acid formation on the
other hand. As might be expected, a rise in the growth curve
always preceded! slightly a rise in acidity. Lord and Nye (1919)
have reported results of similar natiu'e on pnemnococci grown
in glucose broth. During the first 12 hours of their experiment
the medium was found to change in reaction from Ph 7.65 to
5.25. Up to this point, a rapid increase in the number of cells
was evident, but during the subsequent acidification to the final
Pb, 5.15, a rapid decrease in viable organisms was apparent.
178 LAURENCE P. FOSTER
In both of these investigations it is evident that the maximum
changes in acid formation take place simultaneously with a
rapid development and multiplication of the bacteria and thus
show a conformity with the conception of Slator (1916) that
'' Chemical reactions brought about by microorganisms usually
proceed imder conditions where development of the organism
and changes in the composition of the nutrient medium take
place simultaneously." H. M. Jones (1920a) however, has
recently obtained results which contradict the work of Cullen
and Chesney, and Lord and Nye. Using cultures of pneumo-
cocci in glucose broth this investigator has shown that the growth
curve rises sharply at the fotui;h to fifth hour while the onset of
the maximum period of acid formation is delayed until the
twelfth hour. Examination of the cm^es of this experiment
shows the maximum period of growth to be associated with but
a slight alteration in the reaction of the medimn (7.4-7.0),
whereas, the interval of acid formation at a mRyinmiTn rate corre-
sponds with the period of growth at a decreasing rate. This
finding corresponds more or less closely to the observations of
Cohen and Clark (1918) upon BacL coli in ^ucose broth cultures.
The growth ciure was foimd to rise five hours previous to the
onset of the maximum period of acid production, and, as in
the experiments of Jones, the maximum period of acid formation
was found to be coincident with the period of growth at a decreas-
ing rate. At the point where strong symptoms of growth inhibi-
tion appeared, the Ph was found to correspond to the region at
which acetic acid had been previously shown to check growth
(5.6-5.7). The fermentative activity, however, was not seri-
ously checked until the culture approached the region in which
HCl had been foimd to inhibit growth (4.6-5.0). From a con-
sideration of these findings it will appear, in the cases of Bad.
coli and the pneumococcus at least, that the hydrogen-ion con-
centration may exert independent effects upon growth, on the
one hand, and upon acid formation on the other, so that in
experiments designed to follow the acid production of organisms
in carbohydrate media it will be unsafe to assume that maximum
changes m reaction parallel maximum rates of multipUcation of
bacterial cells.
STREPTOCOCCUS HEMOLTTICTJS 179
•
Clark (1915b), working with Bad. colt, was perhaps the first
to follow reaction changes in bacterial cultiures by means ot
determinations of hydrogen-ion concentration. No change in
Pb was noted under a period of ten hours in his experiment.
Itano (1916a) followed the changes in acidity in cultures of
B, sybiilis and noted in certain media of unfavorable initial Pb
that an ''automatic adjustment" toward a more favorable reaction
occurred during incubation. Working with Clostridium perfringens
(C. welchu) and C. sparogenea (Metchnikoflf), Wolf and Harris
(1917b) foimd that curves of acidity change followed closely
those of amino acid formation and gas production. Avery and
Cullen (1919b) used media of different initial Pb with pneiuno-
cocci and demonstrated that after completion of lag, growth, as
evidenced by the rate of reaction change, proceeded at about
equal speeds. Neither the final Pb nor the rate of acid for-
mation was affected by the use of various available mono- or
di-saccharides* The maximum period was found to lie between
the fourth and eighth hours following seeding. Bimker (19l9)
noted an initial acidity rise followed by alkaline reversion in cul-
tmres of Corynehact. diphOieriae and apparently has shown that
toxin production is closely associated with this phenomenon, as
no toxin could be demonstrated in cultiu:^ which failed to exhibit
an alkaline reversion. In a study of the logarithmic or maxi-
miun period in cultures of several organisms by Cohen and
Clark (1918) it was observed that bacteria may multiply rapidly
for a time in media varying considerably in initial reaction.
The maximum period of growth in the case of Bact coli fell
between the fifth and tenth hours. Schoenholz and Meyer
(1919), in their work on Bojct. typhosum, have reported changes
in the growth curve through the influence of hydrogen-ion con-
centration. Thus they foimd that growth at a maximum rate
set in five hours following incubation, if the initial Pb of the
medimn was 7.0. At lower and higher levels lag was of longer
duration.
Avery and Cullen (1919a), using streptococci of human and
bovine origin, found the greatest increase in acidity between the
seventh and twelfth hours, using eighteen-hour cultures as
1
180 LAUEBNGE F. FOSTER
sources of inocula. H. Jones (1920) has recently observed that
in the case of pathogenic streptococci the age of the parent
culture employed may exert a considerable infliience upon the
abundance of growth in sub-cultures which may, in turn, be
reflected in the final Pb values. He also observed that cultures
which were placed under conditions which tended to delay growth
failed to show the characteristic final Pb. The statement fre-
quently made that the final Pb of an organism is eventually
reached, provided the culture exhibits growth, obviously can not
apply to a delicate organism such as the streptococcus. Thro
(1915) called attention to the same fact in his observation that
with streptococci variations in luxuriance of growth were asso-
ciated with differences in the quantities of acid substances
produced.
Slator (1916) has devised an ingenious method for measuring
the rate of growth of a lactic acid-forming organism through an
indirect application of the titration values obtained at definite
intervals throughout the course of the experiment. Using the
formula suggested in a previous work (1917) he was able to show
close agreement in the values of the constant, k, in different
determinations. The possibility of simultaneous acid and alka-
line fermentations in cultiu^es of certain organisms has been
emphasized by Ayers and Rupp (1918) who state that such
actions may complicate and decrease the value of acidity deter-
minations in certain cases. Methods of measuring both fermen-
tations have been suggested by these investigators.
From the foregoing review it would appear that a study of the
progress of reaction changes in cultures of Streptococcus hemolyt-
icusy in order to furnish data of value, must of necessity entail
an investigation of a number of interacting factors. Accord-
ingly, experiments were planned to study the rate of acid
formation as influenced by the following: (1) Amount of inocu-
lum; (2) age of parent culture; (3) presence of a body fluid, horse
serum, (4) initial reaction of medium.
STREPTOCOCCUS HBMOLTTICTJS
181
Experiment VI. The inflrience of (he amount of inoculum upon
the rate of acid formation in glucose broth
Twenty cubic centimeters of 1 per cent glucose broth, Ph
7.10, were inoculated with varying amounts of an active, eighteen
hour culture of Streptococcus hemolyticus in 1 per cent glucose
broth and incubated. At two-hour intervals Ph determinations
were made on 1 cc. samples removed from the cultures with
aseptic precautions. AU cultures remained imcontaminated
throughout the entire period of the experiment. The results of
the experiment are to be found in table 5 and figure 3.
TABLE 5
(Experiment VI)
NUMBEB
IlfOCTTLUM
DCTBATION
8TATIONAJIT
PBBIOD
DUAATION
LAO PSKIOD
OMBSTOr
MAXIMUM
PBBIOD
DUBAnOH
M/XIMUM
PBBIOD
PhLOWBBING fMAXIMUM
PBBIOD)
Tota]
Per hour
1
2
3
4
5
ee.
0.2
0.4
0.8
2.0
4.0
koura
8
2
None
None
None
haura
6+
8 -
8^
6
4
10
8
6
4
2
4
2
6
0.8
1.35
1.40
1.45
0.4
0.34
0.70
0.24
Reference to the curves (fig. 3) shows that the rates of acid
formation are at least roughly proportional to the quantities of
inoculum used. It is interesting to find that the hourly rate
(table 5) during the maximum period is least in the case of (5)
notwithstanding the fact that this contained the largest inoculiun.
In other words, cultiures (4), (3), and (2) though showing more
prolonged lag periods than (5), are able to proceed with acid
formation at more rapid rates, once the maximum period is
initated. No Ph determinations were made within the initial
two-hour interval, hence it is not possible to assume that any
of the cultures showed an entire absence of the stationary period.
In (4) and (6), however, the stationary period, if present, was
probably of very short duration.
J
1
182
LAtTBENCE F. FOSTBB
5
^
i
(f
o
I!
t «
i
p
o ».
^ o
3 «
H o
03
H
03
CO
o
M
PC4
§
«
s
So
04
STREPTOCOCCUS HEMOLTTICUS
183
Experimerd VII. The relaiian of the age of parent culture to the
rate of add formation in glucose broth
Four cultures of Streptococcus hemolyticus were made in the usual
manner at intervals of six hours. After eighteen hours incubation
sub-cultures were made and these second-generation cultures incu-
bated. The schedule was so arranged that at the time of the
final inoculation into the mediiun of the experiment (20 cc. por-
tions of 1 per cent glucose broth) organisms would be taken from
parent cultures of six, twelve, eighteen and twenty-four-hours
age. One hour previous to the final seeding coimts of each
parent culture were made by the method of Wright in order
that each tube of broth to be used in the experiment might
receive approximately the same number of organisms. The
inoculiun was based upon the proportion, 0.8 cc. <rf a twenty-
four-hoiu: culture per 20 cc. of broth.
Bacterial counts
MUMBBB
AOB
OBGANIBlfS
XKOOULUlf
hourt
mUlionM per eu. mm.
ce.
1
6
248
7.40
2
- 12
1068
1.68
3
18
1548
1.48
4
24
2282
0.80 (basis)
Examination of the curves (fig. 4) shows that (2) (from twelve
hour culture) reaches the characteristic final Ph earliest, then
come in order the tubes from the six-, eighteen- and twenty-four-
hour parent cultures. The onset of the maximum period is seen
to follow the same order. As might be expected, the differences
are shown almost entirely in the duration of the lag and station-
ary periods of the four cultures. It is a fact of interest and
importance that the rates of acid formation during the maximum
period (table 6) were practically equal in the four cases.
From a consideration of the work of various investigators
upon the life phases of an organism the results obtained here are
not unexpected. It has been repeatedly demonstrated that the
maximum rate of acid formation in glucose broth occurs between
JOUBHAL or BACTBBIOLOGT, TOL. ▼!, NO. 2
184
LATTBENCE F. FOSTER
OP
?
^
o
^
r "
e
z
o
0*
l\
m
^
■
" g
\
^v
^
g
1 \
Ni.
n3
1 \
>s
P
1 \
V
O
1
\
1
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\
\
5 ^
si
-: g 00
1
\
V
< X
1
\
\
>
V
\
M
1
>
^
\
I
1
^^^^
\
. o ^
I
t
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^ B PS
1
1
^^^^
\
2 o
I
\
^^s
&\
^ b
\
\ ^
(
a\
B
i\
\ •
V
N
V
^^^
-
■
9 %
» a
si
s
PS
S
•
•
o
^'"
^ t\l
'^
"^"
«0
O
"w"
■^
V» CD
O M
•^
VJ
n^
*0
^
s
^
**i
V>
>^
vi
vsf >i;
n; n
^:
C^:
STREPT0C6CCUS HEMOLYTICTJ8
185
the sixth and twelfth hours of incubation, provided the inoc-
ulum be taken from an eighteen-hour parent culture. If it be
assumed that during this interval the organisms are growing
rapidly and that their metabolic activities are at a maximum it
would be anticipated that transplantation of organisms during
this period to a favorable medium would result in resumption of
growth and metabolism with a minimum of lag. The close
parallelism in the curves of (1) and (2) bears out this supposition.
That the organisms decrease progressively in vitality with the
lengthening of their period of contact with the products of their
own metabolism is brought out in the curves of (3) and (4).
TABLE 6
Experiment VII
NCMBBB
AQB OF PAR-
■MTCDI/riTRS
DUIIATION
BTATIONABT
PKBXOD
DUBATIOM
LAO PBBIOD
OMsvror
MAXIMUM
PBBIOO
Dn&ATIOK
MAXnCTTM
PVBXOD
Ph LOwnxNo
(maximum pbbiod)
Total
Per hour
1
2
3
4
houra
6
12
18
24
houra
0
0
0
4
hot/^a
4
2
6
8
4
2
6
12
houra
2
2
2
2(?)
•
0.90
0.90
0.85
0.80
0.45
0.45
0.425
0.40
Here are seen more prolonged lag periods, indicating that the
organisms required more time to recover from the injury sus-
tained in the previous environment. The injury, however,
appears to be only temporary for in all cases acid production is
seen to proceed at practically the same rate following the onset
of the maximum period. The entire absence of lag in acid
production has never been observed with the streptococcus.
Experiment VIII. The rates of add formaiion of Streptococcus
hemolyticus in glucose broth and in glucose-serum broth
Forty cubic centimeter portions of infusion broth (initial Ph
7.20) containing (1) 1 per cent glucose, and (2) 1 per cent glucose
plus 5* i)er cent horse serum were inoculated with 1.6 cc. of an
eighteen-hour glucose broth culture and incubated at 37°.
Determinations of hydrogen-ion concentration were made at
186
LAURENCE F. FOSTER
•
5
O
9>9
tf
<
c
o
n
H
00
O
P
•J
o
o
O 8
>* PS
P
«
S
I
fa
a
8
P
o
E«
H
H
o
^
W 3
o
Vft*
N
Vi
J
3
C4
STREPTOCOCCUS HEMOLYTICUS 187
the outset and at two-hour mtervals by removing aseptically 2
ec. of material from the flasks. The experiment continued
through twelve hoiu^, at the conclusion of which period both
cultures had reached their characteristic final level of Ph.
The outstanding fact here, as may readily be seen by reference
to the curves (fig. 5); is a more rapid attainment of high levels of
acidity on the part of the culture containing horse sermn.
Though a stationary period of two hours is noted in each, the
lag in the glucose culture- is of two hours longer duration than in
the glucose-serum culture. A close parallelism in rates is seen
during the maximum period.
It would seem logical to expect that the differences manifest
in the above experiment would be closely correlated with the
rates of increase in numbers of cells in the two cultures; in other
words, multipUcation at a maximuni rate would be initiated
earlier in the serum-glucose medium. It is a well recognized
fact that we have at our disposal no very satisfactory method
of enimierating viable streptococci. The method of Wright,
though useful in the standardization of bacterial vaccines, gives
only approximate results, and moreover, furnishes values whicji
represent the total organisms, viable and nonviable, present in
a culture. On the other hand, the method of plating dilutions
of a culture which is recognized as valuable in numerical deter-
minations of such organisms as Bad. coli and Bad. typhosum,
is not adequate for enumerations of streptococci owing to the
fact that single colonies upon the plate almost invariably repre-
sent streptococcal chains of varjring length. Moreover, there
arises a possibiUty of the breaking up of coccal chains through
the mechanical disturbance occasioned in preparing dilutions of
the ctdture.
Though the inadequacies of these two procedures were recog-
nized it was nevertheless considered advisable to repeat experi-
ment VIII supplementing the Ph determinations at two-hour
intervals with estimations of the number of viable organisms
through the mediimi of plate coimts.
188
LAI7BENCE F. FOSTER
Experiment IX. The relationship between the rates of add forma-
tion and growth of Streptococcus hemolyticus in glucose
broth and in glucose-serum broth
Forty cubic centimeter portions of 1 per cent glucose broth
and 1 per cent glucose-5 per cent horse-serum broth were pre-
pared and incubated to insure sterility. Inoculations were
made from an eighteen-hour, second-generation culture in 1
per cent glucose broth into the two lots of media. Ph deter-
minations and plating of dilutions were carried out every two
hours. The experiment continued through twelve hours.
Technic of plating. 1.8 cc. of plain broth were used as dilut-
ing fluid throu^out. 0.2 cc. of culture was transferred into
this amoimt of broth and the fluids mixed by carefully drawing
up and down in the pipette, after which 0.2 cc. of this dilution
were added to 1.8 cc. of broth, etc. imtil all the dilutions required
had been made. Especial care was taken to avoid agitation of
the material during the preparation of the dilutions. Nutrient
agar containing 10 per cent of defibrinated rabbit's blood was
used as a plating medium.
Table 7 contains the results of the e^eriment.
TABLET
Experiment IX
GLUCOBB
OLUCOSBSXBUM
BOVBS
Ph
Counts*
Ph
Counta*
0
2
4
6
8
10
12
7.65
7.65
7.60
7.50
6.80
5.90
5.60
1.68
0.38
158.00
1,498.00
3,243.00
260,000.00
Infinite
7.65
7.65
7.20
5.90
5.15
5.05
4.90
1.68
40.30
140.00
76,000.00
713,600.00
Infinite
1,040,000.00
* Counts are expressed in millions per cubic millimeter.
Attempts to construct growth curves by plotting the loga-
rithms of counts against time brought out certain irregularities
which made impossible the formation of smooth curves. Con-
STREPTOCOCCUS HBMOLYTICXJS
189
•
:?
o
I
ft
w
il
ft
i
x3
5!
<X> ^ N 5f >S <0 ^
^ ^ Vi* V> »0 Vi v«
«si
CO
M
M ^ v»
nS^ Ml >s»
^ ^ W ^ vA q>
\» N ^: N ^: ^
S
o
190
LAURENCE F. POSTER
sequently this procedure was abandoned. Curves of acid
formation are shown in figure 6. At each point on the curves
the number of organisms, expressed as millions per cubic milli-
meter, is shown. Examination of figure 6 shows that the two
curves are analogous to those of experiment VIII (fig. 5), thougih
the lag registered by the glucose-serum culture is of less duration.
The numbers of viable organisms as showh by plate counts bear
out the assumption that the earUer rise in acidity in a glucose-
serum broth is associated with a corresponding period of multi-
plication at a rapid rate.
Experiment X. The relation of the initial Pa of glucose-broth to
the rate of add formation by Streptococcus hemolyticus
Beef infusion broth was adjusted to various Ph levels, divided
into six portions, and sterilized in the usual manner. After
adding the proper amoimt of glucose, the tubes, containing 20
TABLE 8
Experiment X
NUMBER
Ph
(initial)
DURA-
TION OP
STATION-
ART
PEBIOD
DURA-
TION or
LAO
PEBIOD
ONSET OP MAXIMUM PEBIOD
DUBA-
TioN or
MAXI-
MUM
PEBIOD
Pr LOWKBTKO
(maximum PKHIOO)
Total
Per hour
1
2
6.20
6.20
10
No growth
Not reached in 14 hours
3
7.00
2
4
6th hour
2
0.85
0.425
4
7.50
2
2
4th hour
4
1.70
0.425
5
8.10
2
4
6th hour
2
1.26
0.625
6
8.65
2
?
Not reached
?
cc. of medium each, were incubated to insure sterility. The
inoculum consisted of 1.33 cc. of an eighteen-hour second-genera-
tion culture in 1 per cent glucose broth. A massive inoculum
was employed to complete the experiment within the fourteen
hours. The results are foimd in table 8.
Reference to figure 7 reveals an interesting point, namely,
that the cultures of initial Ph 7.0, 7.5, 8.1 reached practically
the same level of hydrogen-ion concentration after dght hoiu^
STREPTOCOCCUS HBMOLYTICU8
191
incubation. To attain this result the cultures of necessity
must have produced acid at varying rates. That this was true
is brought out by the curves which show a tendency toward
convergence after the second hour. From the data in table 8 it
Hours
Fig. 7. Experiment X. The Influence of Initial Ph of Bboth Upon the
Rate of Aciditt Formation
appears that culture (4) exhibited the shortest lag (two hours)
though culture (5) showed the most rapid rate of acid formation
diuring the maximum period, namely, a lowering of 0.625 Ph
against a lowering of 0.425 Ph in the cases of (4) and (3). Culture
192
LAUREXCE F. FOSTER
(6) began its acid fonnation after two hours at a slow, rather
constant rate but at the close of the experiment had only reached
a Ph of 7.0. After thirty hours its Ph was 6.0. It was not
known whether this culture ever reached the final characteristic
hydrogeurion concentration. Culture (1) showed no growth
while (2) was found to grow very poorly, the Ph after thirty
hours being at the same level as at the f ourteen-hour period.
TABLE 9
Summary
BZPBBI-
MBirr
AOB<»'
PLBUBAL
TLUIO
DUBA-
TION
0TATIOK-
ABT
PBBIOD
DUBA*
InON LAO
PBBIOO
ONSBT
MAZl-
llUlf
PBBIOD
Ph
(nmzAL)
Ph oranob
IfAXOCTTM
PBBIOD
DUBA-
TION
IfAXI-
MUM
PBBIOD
Ph LOWBBoro
Total
Per hour
Medium: 1 per
cent glucose broth
daye
houra
koura
houra
VI
18
4
4
8
7.10
6.46-6.70
4
1.36
0.34
VII
19
Undei2
6
6
7.25
6.70-5.85
2
0.85
0.425
VIII
18
3
5
8
7.20
6.60-n5.70
2
0.90
0.45
IX
24
2
6
8
7.65
6.80-5.90
2
0.90
0.45
VIII
IX
18
24
2
2
4
2
6
4
7.25
7.65
6.70^.70
7.20-5.90
2
2
1.00
1.30
0.50
0.65
From the foregoing data the following conclusions r^arding
the rate of acid formation in cultures of Streptococcus hemolyticus
may be drawn:
1. The curves of acid formation with time may be separated
into five characteristic periods: (1) Stationary period, (2) lag
period, (3) maximum period, (4) period of negative acceleration,
(5) maximum stationary period.
2. It is possible to reduce the duration of the stationary and
lag periods to a minimum through increasing the quantity of
inoculum. Whether this holds beyond a certain point is not
known.
3. The age of the culture that is serving as a source of inocu-
lum may exert a decided effect upon the duration of the station-
ary and lag periods in the sub-culture. If the inoculum be taken
from a culture during its maximum period, lag is reduced to a
STREPTOCOCCUS HBMOLYTICUS 193
minimum in the sub-culture and growth and acid production at
a maximiun rate are initiated early. This point is of consider-
able importance, though seemmgly it has been overlooked by
many workers.
4. The presence of 5 per cent horse serum reduces lag by from
two to four hours. This is correlated with an earlier period of
multiplication of organisms at a maximiun rate. Two possible
explanations of this phenomenon present themselves: (1) Nutri-
tive materials in some easily available form may be furnished by
the serum or, (2) growth-accessory substances (vitamines) may
be present in the enriching fluid. The second possibility would
be in accord with Kligler's finding (1919) that the presence of
tissue extracts shortened lag in the growth of Streptococcus hemo-
lyticus and other organisms. Ordinarily these accessory sub-
stances are furnished by disintegrating cells which accoimts for
the fact that massive inocula give better cultiures than light
inocula.
5. Entire absence of lag in acid formation has never been
noted. One case has been reported above in which a two-hour
lag was apparent in glucose-serum broth.
6. In glucose broth the maximiun period is initiated between
the sixth and eighth hour and is usually maintained for two
hours after which the period of negative acceleration sets in.
The Pb decrease per hour in this medium is 0.42 (average of
four experiments). In glucose-serum broth the maximum
periods sets in two to foiu* hours earlier and proceeds for two
hours. The Pa decrease per hoiu: during this period is 0.50.
Recent work in this laboratory by Dr. Marjorie W. Cook has
demonstrated that hemotoxin production by the ''H" strain of
Streptococcus hemolyticus occiu's nearly always between the
sixth and eighth hours. It is a fact of interest that this property
appears during the interval which is most frequently associated
with maximum acid formation.
7. In glucose broth of initial Ph ranging from 7.10 to 7.65 the
maximum period sets in when the Ph of the cultiu'e has been
brought to 6.45^.80. The relation of this level of acidity to
the optimiun Ph of the enzymes associated with acid production
might be suggested as a possible explanation of this phenomenon.
194 LAT7BENCE F. FOSTER
8. The initial Pb of broth exerts an effect upon the rate of
acid formation. A medium of Ph 7.5 was found to show a mini-
mum of lag, while the most rapid acid fonnation occurred in
broth of Ph 8.1. The optimum Ph of broth for growth and
acid production of the ^'H" strain of Streptococci hemolyticu8
apparently lies between these two points, Ph 7.5-8.1. Other
observers have fixed the optimum Ph of the streptococcus at 7.8.
IV. THE INFLUENCE OF THE INITIAL Ph OF BROTH UPON GROWTH
AND ACID FORMATION OF STREPTOCOCCUS HEMOLYTICUS
Before the elaboration of acciu'ate methods for determining
the true reaction of a medium much attention was given to the
study of the influence of acidity and alkalinity upon the physio-
logical activities of organisms. Unfortunately much of the
data obtained in these earlier investigations is of little value
owing to the fact that determinations of titratable acidity rather
than of true acidity were carried out. The fallacy of titrating
media by the older method has been established by Clark (1915a)
beyond question and if we are to accept the classic works of
Sorensen and Michaelis, as supplemented by a constantly
increasing mass of data by other investigators, it must be sup-
posed that the hydrogen-ion concentration rather than the titrat-
able acidity of the environmental medium is the determining
factor in regulating the metabolic activities of bacteria and
related organisms.
Though it is true that media adjusted by the old titration
method may vary considerably in their hydrogen-ion concen-
trations yet it has been possible in the past to cultivate bacteria
with a considerable degree of success. No doubt this has been
due rather to the fact that many bacteria are able to develop
within a fairly wide range of reaction than to the accuracy of
adjustment of the media. The effect of variations in initial Pb
would be demonstrable rather in altered rates of growth and
fermentation. In the case of some of the more delicate patho-
genic bacteria, small variations in reaction may induce very
decided effects and it is here particularly that the true reaction
STREPTOCOCCUS HEMOLYTICU8 195
must be carefully controlled. One example may serve to illus-
trate this point : H. M. Jones (1920) working with the various types
of pneumococci found that in a mediimi of Ph 7.0 no strain was
able to develop greater acidity than Ph 5.6, whereas if the initial
reaction was Ph 7.6 all strains gave a final hydrogen-ion concen-
tration ranging from 5.0 to 5.4. If the final Ph produced by
certain organisms is to serve a useful purpose in differential pro-
cedures, the level of the initial hydrogen-ion concentration of
the medimn must obviously be controlled so as to permit the
optimmn development of the organism in question, in order that
it may carry its fermentation to a maximum.
That there are levels of hydrogen-ion concentration which have
the effect of limiting the activities of certain organisms was
perhaps first recognized by Lazarus (1908) in 1908, who roughly
adjusted her media to various hydrogen-ion concentrations with
Htmus, phenolphthalein, and methyl orange after which the reac-
tions limiting growth were studied. The influence of reaction
was considered a modification of the conditions of assimilation
in that it exerted a definite effect upon the state of dissociation
of the materials which the organism in question could take up
or could alter.
With the recognition by investigators of the growing impor-
tance of the relationships of hydrogen-ion concentration to bio-
logical process in general, have come attempts to determine the
limits of reaction within which bacteria may develop. The
most complete single effort to establish such minimum, maxi-
mum, and optimum limits of Ph for a nmnber of pathogenic
organisms seems to have been that of Fennel and Fisher (1919).
In the course of the present investigation it has been possible to
collect from a niunber of sources data bearing on this point and
in recognition of the value of a compilation such as this to work-
ers in the field of bacteriology this information has been appended
to the present section of the paper.
196
LAUBENCE F. FOSTEB
Experiment XI. The relation of initial hydrogen4on concenbraiion
of broth to the growth of Streptococcus hemolytunia
Portions of infusion broth were adjusted to values ranging
from Ph 5.0 to 9.0 and after the addition of proper amounts of
glucose and horse serum, were incubated for twenty-four hours
to insure sterility. Each tube contained 5 cc. of medium. The
following series were used: (1) Plain broth, (2) 1 per cent glucose
broth, (3) 1 per cent glucose-5 per cent horse serum broth.
The inoculiun consisted of 0.2 cc. of an eighteen-hoiu: culture in
1 per cent glucose broth. Duplicate iminoculated tubes were
carried as controls. The results are found in table 10.
The following summary will perhaps serve better to express
the outstanding points of this experiment :
Minimum Pb permitting growth
Maximum Ph permitting growth
Ph limits within which luxuriant growth occurs <
vums
BBOTH
Ipbbcbmt
OLUCOBS-
BBOm
IPBBOBKT
OLUOOBBv
Smtotan
■■BUM-
BBOTB
6.35
8.60+
6.60
8.50
6.35
8.50+
6.35
8.50
5.70
9.25+
5.90
9.25
Whereas the limits of reaction which permit growth appear
to be the same in plain and in 1 per cent glucose broth, the
presence of horse serum in addition to the glucose enables the
organisms to tolerate greater degrees of acidity and alkalinity.
Hence it is to be emphasized that in expressing the levels of
hydrogen-ion concentration which limit the growth of organisms
the exact composition of the experimental media must be men-
tioned. It has been noted previously that horse serum exerts a
strong stimulatory effect upon the growth and fermentative
activities of the streptococcus. Here we find additional evidence
of such an action in an increased tolerance of the organisms for
acidity and alkalinity, manifested by growth throughout a wider
range of hydrogen-ion concentration.
From the results of experiment VIII it must be concluded that
the optimum Pb, based upon the rate of acid formation in 1
STREPTOCOCCUS HEMOLYTICTJS
197
per cent glucose broth, lies between Ph 7.5 and 8.1. If the mean
of these two exponents be taken, the value, Ph 7.8, represents the
optunum hydrogen-ion concentration for growth and acid pro-
duction. This corresponds to the optimum found by Fennel
and Fisher (1919) for Streptococcus hemolyticus. It is interesting
to note that this point corresponds exactly to the optimum estab-
lished for the pneumococcus (see chart) and other pathogenic
cocci, and that it is only slightly different from the Ph of human
blood.
TABLE 10
Experiment XI
1 PCR CKKT OLUCOBE BROTB
1 PXB CBlfT GLTTCOSB, 5 PBB
PLAIN BBOTH Ph
Ph
CXNT ROBSB BBRUM BBOTH
NITMBKB
'- u
Ph
Initul
48 hours
Control
Initial
48 houTB
Control
Initial
48 honn
Control
1
6.00
_
6.0
6.0
...
6.0
6.0
6.0
2
6.30
—
6.4
6.3
—
6.4
6.6
6.4=b
6.7
3
6.60
—
6.66
6.6
—
6.66
6.7
6.1+
6.7
4
6.70
—
6.60
6.7
—
6.6
6.9
6.06+++
6.9
6
6.06
—
6.00
6.06
6.96=^
6.0
6.3
6.00+++
6.3
6
6.36
5.5++
6.36
6.36
6.20++
6.36
6.4
6.00+++
6.4
7
6.60
6.0+++
6.70
6.60
6.16+++
6.70
6.80
6.00+++
6.80
8
7.00
6. 16+++
6.96
7.00
6.264-++
6.96
7.00
6.00+++
7.06
9
7.16
6.40+++
—
7.16
6.20+++
—
7.20
6.00+++
7.20
10
7.46
6.ao+++
7.30
7.46
6.1+++
7.30
7.60
6.00+++
7.40
11
7.86
6.80+++
7.60
7 86
6.26+++
7.60
7.70
4.90+++
7.66
12
8.10
7.00+++
—
8.10
6.20+++
—
8.10
6.00+++
8.10
13
8.36
6.90+++
8.26
8 36
6.20+++
8.26
8.30
6.00+++
8.30
14
8.70
8.10++
8.60
8.70
6.20+++
8.60
8.7
6. 10+++
8.60
16
9.40
—
8.96
9.40
8.96
9.26
6.20++
8.90
— No growth; =fc growth doubtful; + fair growth; ++ good growth; +++
excellent growth.
Wolf and Harris (1917a) working with Chstridium welchii and C.
sporogenes have found that the final hydrogen-ion concentration
produced by these organisms in media adjusted to different
levels is by no means a constant. By constructing curves to
show what they term "reaction resultants" an orderly relation-
ship between the point of initial and final Ph was noted. More-
over, in media adjusted within the acid range the character of
the ''reaction resultant" curve was dependent upon the type of
198 LAURENCE F. FOSTER
acid employed in fixing the initial reaction of the medium. Fur-
ther doubt has been thrown upon the '^phjrsiological constant"
theory by the work of Wyeth (1918) on Bact. coli. By constructing
'^reaction resiiltants" such as those suggested by Wolf and Harris
(1917a) he was able to show a definite relationship between the
initial and final Pb levels. The type of acid employed in adjusting
the medium was also f oimd to bear a definite relationship to the
final Ph produced by the organisms. From the foregoing results
these investigators concluded that no method of clinical differen-
tiation based upon the production of a characteristic level of
hydrogen-ion concentration may safely be applied, imless such
factors as the initial Ph of the culture mediiun as well as its
composition be very carefully controlled in every test.
Wolf and Harris (ibid.) have directed attention to the fact
that fermentations characterized by a slowly decreasing produc-
tion of acid in the period of depressed acceleration give rise
to a final Ph which is a constant regardless of the initial reaction,
provided the activities of the organism cease as soon as a definite
level of Ph is attained. Expressed differently, the "reaction
resultant" appears as a straight line parallel to the abscissa.
Seemingly this condition prevails in streptococcus fermentations
as table 10 reveals a marked constancy in the levels of final
Ph produced in glucose and in glucose-sermn media. So far as
the initial reaction is concerned it must be concluded that this
factor is without influence upon the production of a character-
istic hydrogen-ion concentration but that levels of initial Ph
which allow growth to occur satisfactorily will also conduce to
the attainment of the Ph level established as a "physiological
constant" of Streptococcus hemolyticus. That the composition
of the medium may exert an effect upon the final Ph however,
is illustrated in the values obtained with the glucose-serum
series (table 10). Here there is a tendency toward the produc-
tion of slightly higher points of hydrogen-ion concentration,
that is, lower Ph levels.
Limits of hydrogen-ion concentration which permit growth of organisms
OBaANBM
BBTBBBNCB
MBOIVM
MINIMUM
MAXI-
MUM
OPTIMUM
Pneumococcus
Demby and Av-
ery (1918)
Fennel and Fish-
Infusion broth
7.0
8.3
7.8
er (1919)
Infusion broth
7.2
8.2
7.8
Avery and Cul-
len (1919b)
Infusion broth
7.0
8.3
7.8
Streptococcus
Fennel and Fish-
Infusion broth
4.5
8.0
7.6-7.8
hemolyticus
er (1919)
Foster
Infusion broth (1
per cent glucose)
6.35
8.5+
7.8
Infusion broth (1
per cent glu-
cose, 5 per cent
cent horse se-
nim)
5.7
9.25+
»
Infusion broth
6.35
8.5+
Streptococcus
Grace and High-
Ascites broth
6.40
8.00
6.8
viridans
berger (1920a)
Fennel and Fish-
*
4.50
8.00
7.6-7.8
er (1919)
Streptococcus
Itano (1916b)
2^Xl0-«
erysipelatis
Meningococ-
Fennel and Fish-
Glucose-agar
7.40
7.80
7.6
cus
er (1919)
%
Gates
Senim-glucose
broth
6.10
7.80
7.4
Gonococcus
Cole and Liloyd
(1917)
"Tryptamine
B. E."
6.50
9.10
7,6
Fennel and Fish-
Starch-agar
7.0
8.00
7.6
er (1919)
(Vedder)
Bact, coli
Michaelis and
Marcora (1912)
Lactose broth
5.0
1
Shohl and Janney
Urine
4.6-5.0
9.2-9.6
6.0-7.0
(1917)
Wyeth (1918)
Infusion broth
4.30
(HCl)
Wyeth (1918)
Infusion broth
4.52
(lactic)
Wyeth (1918)
Infusion broth
4.77
(acetic)
199
200
LAURBNCE F. FOSTER
Limita of hydrogen-ion conceniraiion which permit growth of organiems — continued
OBOAnrmii
BXrBBXNCB
MBOIUM
luiriMinf
MAXI-
MUM
OPriMTTM
Bact. typhosum
Fennel and Fish-
er (1919)
Schoenholz and
Meyer (1919)
Nutrient agar
4.00
5.00
9.60
8.60
6.2-7.2
6.8-7.0
Bact, paraty-
phosum (A)
Fennel and Fish-
er (1919)
Nutrient agar
4.00
9.60
6.2-7.2
Bact. paraty^
phoeum (B)
Fennel and Fish-
er (1919)
Nutrient agar
4.00
9.60
6.2-7.2
BMt, dysente-
riae (Flex-
ner)
Fennel and Fish-
er (1919)
Nutrient agar
4.80
9.60
6.2-8.4
Bact, dysente-
riae (Shiga)
Fennel and Fish-
er (1919)
Nutrient agar
4.80
9.60
6.2-8.4
C. welchii
Wolf and Harris
(1917a)
Glucose-peptone
(2 per cent)
water
4.8
C. metchnikoff
Wolf and Harris
(1917a)
Glucose-peptone
(2 per cent)
water
4.94
Hemophilus
influemae
Fennel and Fish-
er (1917a)
Chocolate medi-
um
7.8-8.0
Coryn^act,
diphtheriae
Bunker (1916-17)
6.30
8.20
6.5-7.5
V. choleras
Fennel and Fish-
er (1919)
Extract agar or
broth
5.60
9.60
6.2-8.0
B. melitensis
Fennel and Fish-
er (1919)
Nutrient agar
6.30
8.40
6.6-«.2
STREPTOCOCCUS HEMOLYTICU8
201
Reaction of dijjereniial media
OMBBVKB
MSDXVM
Ph
(mimzmxtm)
Ph
(UAZniUM)
Ph
(OPIXMUM)
Fennel and Fisher (1919)
Endo
7.8-8.0
Kligler (1918)
7.8^.0
Fennel and Fisher (1919)
Brilliant green
6.40
7.20
6.8-7.0
Kligler (1918)
7.0-7.2
Meyer and Stickel (1918)
6.4r.7.0
Fennel and Fisher (1919)
Riissers double su-
gar
7.0
7.8
7.4r.7.6
Kligler (1918)
7.4
V. THE RELATION OF HYDROGEN-ION CONCENTRATION TO INHIBI-
TION AND DEATH OF STREPTOCOCCUS HEMOLYTICUS
It has long been noted that the growth of a microorganism be-
yond a certain point exhibits sjrmptoms of inhibition, manifest
first in a decreasing growth rate, second by complete cessation
of growth, third by a definite decrease in numbers, and finally
by death, at which point the culture becomes entirely sterile.
Inhibition, representing as it does an almost miiversal bacterio-
logical phenomenon, ensues from the toxic action of the products
of its own metabolism upon the organism itself. Through the
continuous accumulation of these waste products in the encom-
passing medium and through the inability of the organism to
escape their contact inhibition becomes more and more pro-
nounced and eventually death supervenes. If the metabolic
produqts are largely of acid nature these substances will exert a
harmful effect and if in greater concentrations, a fatal influence.
This fact has been well illustrated in the curves of acid formation
previously discussed.
Recognizing this principle, Elitasato (1888) in 1888 added
various acids to neutral media and then determined the mini-
mum dose required to kill BouA. typhosum and V. cholerae, and
the maximum dose which would still permit their growth. As
the results of these experiments were expressed only in terms of
percentage concentration they have for us now only historical
interest.
202 LAURENCE F. FOSTER
Paul and Kronig (1896, 1897) in 1896 pointed out that the
toxicity of metaUic salts for anthrax spores and for cells of
Staphylococcus aureus is dependent chiefly upon the eflfect of
the cation but that the anions and undissociated molecules as
well may exert a certain influence. Strong acids were found to
act in accordance with their concentration of hydrogen ions
and to depend to a small extent upon the specific action of
the particular anion or undissociated molecules. Winslow and
Lockridge (1906) in an extensive study of the toxic effects of
certain acids upon colon and typhoid bacilli found that strong
acids such as HCl and H2SO4 proved fatal in concentrations at
which they were highly ionized, whereas weak acids such as
acetic and benzoic, proved .fatal at concentrations where they
were but slightly ionized. In the latter the effect appeared to
be due rather to the whole molecules than to the actual concen-
tration of hydrogen-ions.
Paul, Birstein, and Reuss (1910a) attributed a considerable
toxic influence to the acid anion present as well as to the undis-
sociated molecules. The toxic action of hydrogen-ions upon the
cell appeared to be catalyzed by anions. This was found to be
especially true of the weak organic acids. This finding has been
supported by Norton and Hsu (1916) who added that the undis-
sociated molecules act as negative catalyzers of the action of the
hydrogen-ions. Addition of a salt having the same anion as the
acid in question was foimd to decrease the disinfecting power
through depression of the hydrogen-ion concentration (common
ion effect), though the retarding influence appeared to be greater
than would be expected from the decreased hydrogen-ion con-
centration alone. Salts not appreciably affecting the ionization
of the acid brought about an increase in disinfecting power.
These conclusions are not in accord with other results reported
by Paul, Birstein, and Reuss (1910b) These observers showed
that salts which exercised no disinfecting power in themselves
were capable of increasing the toxicity of inorganic acids having
the same or different anions.
A direct relationship between the degree of ionization of acids
and their toxicity for yeast cells was reported by Bial (1902)
STREPTOCOCCUS HEMOLYTICUS 203
who accordingly divided the acids used into three classes based
upon their ionization constants and similarity in toxicity. Sur-
prising differences in the toxicity of various acids for molds were
found by J. F. Clark (1899) m 1899. The degree of dissociation
seemingly stood in no relation to the toxicity and this observer
was forced to the conclusion that the inhibitory property, for
molds at least, resided largely in the undissociated molecules.
The approximate concentrations of a niunber of common
inorganic and organic acids required to inhibit growth of Strep-
tococcus pyogenes have been determined by Taylor (1917) in the
course of studies on the disinfection of war wounds. Consider-
able variation in potency was apparent with the organic acids
investigated though apparently no accoimt was taken of their
degrees of ionization.
Wolf and Harris (1917a) in their study of the effect of acids
upon the fermentations of Clostridium wekhii and C. sporogenes
point out that the influence is two-fold; first, that exerted by the
hydrogen-ions, and second, that due to the anions and undisso-
ciated molecules. Lactic acid was found to have about the
same toxicity as hydrochloric, whereas acetic, succinic, and
butyric inhibited growth at lower hydrogen-ion concentrations
(higher Ph). Wyeth (1918) reported similar results with Bdct.
coll. He points out that if the actual mass of acid be considered
hydrochloric was more inhibitory than lactic or acetic acids
but that the lethal points of such organic acids, in terms of
hydrogen-ion concentrations, were lower than that of hydro-
chloric. In equivalent quantities the highly ionized acids
proved more effective in inhibiting growth.
Lord (1919), has obtained data which lead him to believe
that acidity is the principal inhibitory factor in glucose broth
cultures of pneumococcus, though H. M. Jones (1920) very recently
has succeeded in demonstrating that in the presence of body
fluid such as blood serum or ascitic fluid the tolerance of this
organism for hydrogen ions is considerably increased. This
same phenomenon had been noted previous to the appearance of
Jones' article dining the coiu^e of the present investigation
upon Streptococcus hemolyticus and the facts have proved so
204
LAUBENCE F. FOSTER
interesting that they will be presented in this section of the
paper. •
In numerous experiments it has been observed that a glucose
broth culture of Streptococcus hemolyticus, after reaching a sta-
tionary level of hydrogen-ion concentration during the first
twenty-four hours, remains viable for a period varying from two
to five days. Subcultures made on each succeeding day during
this period of death show stationary and lag periods of increasing
duration. To gain some idea of the factors contributing to this
mhibition the following experiments were carried out:
Experiment XII. The growth and add production of Streptococcus
hemolyticus in neutralized fiUrates
A transplant of the usual quantity of an eighteen-hour culture
was made into 1 per cent glucose broth, Ph 7.5, and the material
incubated until sterile (five days). The culture was then filtered
through a sterile Berkefeld candle, after which the filtrate was
brought back to the original reaction with sterile NaOH and
re-inoculated with a fresh, actively growing culture. This
procedure was repeated until no further growth resulted upon
inoculation. The results are found in table 11.
TABLE 11
Experiment XII
rZLTBATI
riNALpH
OBO-WTH
BBOUQHT TO PR
1
2
3
4
5.10
6.00
5.30
+ + +
+ + +
+ + +
7.60
7.60
7.80
From the data shown in table 11, it would appear that acidity
is the chief factor causing inhibition and death of the strepto-
coccus in glucose broth cultures. The inhibition which finally
appears may be due to two factors; first, to an exhaustion of
nutrient materials in the medium, and second to the accumula-
tion of toxic products other than acid which check metabolism
and growth.
STREPTOCOCCUS HBMOLYTICUS 205
Chesney (1916) in a rather extensive investigation of the latent
period of bacteria noted variations in the toxicity of filtrates,
taken at intervals following the maximum period from plain
broth cultures. Inhibition appeared strongest at the time when
the culture had attained the simunit of its growth and became
progressively less as the period of incubation increased. At the
point where the culture became sterile a minimmn of inhibition was
shown. Filtrates taken early in the maximmn period of growth
showed no inhibitory property while those taken near the end
of the same period proved to be somewhat toxic. According to
Chesney the inhibitory substances represent waste products of
the bacterial ceUs or imused portions of food molecules, and the
alteration of the cells occasioned by their exposure to these
toxic materials is concerned with that structure or function
which is essential to metabolism and hence to growth. It must
be emphasized that in Chesney's experiments plain broth cul-
tiu*es were studied and that consequently the factor of acidity
was absent. In fact no determinations of hydrogen-ion concen-
tration were carried out.
It is a well recognized fact that plain broth cultures of the
streptococcus remain viable throughout much longer periods
than do glucose-broth cultures of the organism. This would
tend to substantiate the conclusion drawn from experiment XII
that acidity is the chief single factor causing inhibition and death
of the streptococcus. Natvig (1909) in an investigation of acid
production by the streptococcus arrived at the same conclusion.
Refrigeration of streptococcus cultiu-es is known to be one of
the best means of maintaining the viability of the organisms and
it has been observed in this laboratory that such a procedure is
especially useful in preserving the plemitic exudates employed
as a source of culture material in the present investigation. It
would be expected that the decrease in temperature occasioned
in transferring a culture from the incubator to the ice chest
would reduce the rates of metabolism and growth to a low level.
As a consequence the toxic products of bacterial metabolism
would increase in the mediimi at a much slower rate than if the
culture were incubated. Obviously this condition would tend to
preserve the viability of a culture for long periods.
206 LAURENCE F. FOSTER
Experirneni XIII. The inhibitory action of adds upon a cuUure
of Streptococcus hemolyticus
One per cent glucose broth was inoculated as usual with an
eighteen-hour actively growing culture and permitted to incubate
for eighteen hours. At the end of this interval a portion was
filtered with sterile precautions through a Berkefeld candle and
another portion was centrifugaUzed. Ph determinations were
then made upon the supernatant and the filtrate. Portions of
beef infusion broth containing 0.5 per cent KH1PO4 (to aid in
maintaining the reaction) and 0.5 per cent glucose were next
adjusted to the Ph levels of the cultures, using the acids indicated
in table 12. The supernatant fluid, Berkefeld filtrate, and tubes
containing the broth adjusted with acids were inoculated with
equal amoimts of an eighteen-hom* culture in 1 per cent glucose
broth. Tests of viability were carried out by streaking one
loopful of material on the surface of blood-agar plates at hourly
intervals. As will be seen by reference to table 12 some of the
tubes contained 5 per cent horse serum.
In the cases of (2) and (4) the addition of 5 per cent horse
serum caused a change in Pa toward the alkaline side and con-
sequently the results in these tubes are not comparable with
the others. The rather close agreement in toxicity between
lactic (1) and acetic (2) acids at the same Ph is of interest. The
mixture of the two acids m molecular proportions kiUed m
twelve hours, but inasmuch as the Pb of this tube was 5.15 as
against 5.25 in (1) and (3) the result cannot be considered as
evidence of increased toxicity. By comparing (6) with (1), (3),
and (5) the protective action of horse serum is strikingly illus-
trated. Tube (6) contained viable cells after fifty-four hours
contact with an acidity of 5.20; in other words, the streptococci
were able to tolerate the same degree of acidity for a period
nearly four times longer when in contact with 5 per cent horse-
serum. Close agreement between the toxicities of the super-
natant and filtrate are apparent ((7) and (8)) though neither
proved as toxic as lactic or acetic acids of the same hydrogen-ion
concentration.
STREPTOOOCCU8 HEMOLTTICUS
207
TABLE 12
EzperiTMrU XIII
▼XABILirT AFTBX ROUBS
6
7
8
9
10
11
12
13
14
15
16
17
19
21
32
36
54
ACID
(1)
£
+++
+++
+++
+++
+
+
(2)
1
i
+++
+++
+++
+++
+++
+++
+++
+++
+++
+++
+++
++
60++
10+
6+
4+
CS)
M)
8
to
o
1
<
+ + +
+ + +
+ + +
+ + +
+ +
35++
21++
6+
+++
+++
+++
+++
+++
+++
+++
+++
+++
+++
+++
+++
++
60++
24+
4+
2*
(5)
£
.s
++
++
po++
10+
6+
1-
(•)
I
•2 M
8£
(7)
+++
+++
+++
+++
+++
+++
+++
+++
+++
+++
+++
+++
+++
++
35+
23+
7+
le
Pi
I
a
(8)
+++
+++
+++
+++
+++
+++
+++
+++
+++
+++
+++
++
14+
6+
8
le
iff
I
+++
+++
+++
+++
+++
+++
+++
+++
+++
+++
+++
++
13+
12+
(»)
S
£
+
Numbers represent colonies developing from one loopful of culture.
+++ Profuse growth; ++ good growth; + growth sparse (less than 60 colo-
nies); sfe growth very doubtful (one or two colonies};.— no growth after twenty-
four hours incubation.
BX7MMART
1. Streptococcus h^molyticus is able to ferment the common
hexoses and disaccharides but not the polysaccharides. The
final hydrogen-ion concentration produced in broth containing
different sugars varies between the limits Pb 4.85-5.40. The
lowest Ph is registered in broth containing glucose; the hi^est
Ph in broth containing lactose. The characteristic final Ph is
seldom reached in the first generation but is usually attained by
208 LAURENCE F. F08TEB
the second generation culture. Subsequent transplants do not
show lower levels of Ph.
2. Plain broth cultures of Streptococcus hemolyticus show a
decrease in Ph which is practically the same as that exhibited by
cultiu'es of the organism in sugar-free broth. This is believed to
be due to a selective action upon that portion of the peptone mole-
cule which Pick has shown reacts typically like a carbohydrate.
3. Streptococcus hemolyticus is able to produce its characteris-
tic final Ph in neutral broth containing 0.2 per cent glucose.
Concentrations of glucose up to 1 per cent have no further
effect upon the level of the final Ph.
4. The final hydrogen-ion concentration of the streptococcus
is not influenced by the presence of KsHP04 in concentrations up
to 1 per cent providing sufficient glucose is present.
5. Titration curves show that horse serum in broth exerts a
slight but distinct buffer effect.
6. The curves of acid formation with time may be separated
into five characteristic periods; (1) stationary period, (2) lag
period, (3) maximum period, (4) period of negative acceleration,
and (5) maximiun stationary period.
7. Through an increase in the amoxmt of inoculum or by
employing a parent ^culture of suitable aige as a source of inoc-
ulum it is possible to reduce the stationary and lag periods to a
minimum.
8. The presence of 5 per cent horse serum in glucose broth
reduces lag in acid formation by two to four hours. This may be
due to, (1) the presence of growth-accessory substances, or (2)
the presence of easily available nutritive materials.
9. In glucose broth the maximum period of acid formation
is initiated usually between the sixth and the eighth hours and
is maintained for two hours. Maximiun production of hemo-
toxin has been found to occur between the sixth and the eighth
hours.
10. The most rapid formation of acid takes place in broth
adjusted to a Ph of 8.1, while a minimum of lag is shown in broth
of Ph 7.6. The optimum Ph for acid formation is believed to
lie between these two levels, or at 7.8.
STREPTOCOCCUS HEMOLYTICUS
209
11. The limits of hydrogen-ion concentration which support
growth of Streptococcus hemolyticua are as follows:
Ph
FI«AIN BBOTH
1 PBB CB2n
GLUCOBB
BBOTH
iFBBCBXT
OLUOOBB,
5 PBB CBMT
8KBUM BBOTH
MinimuTn permitting arrowth
6.35
8.50+
6.60-
8.50
6.35
8.50+
6.35-
8.50
5.70
Maximum permitting growth
9 25+
Limits permitting luxuriant growth. . . .<
5.90-
9.25
12. Acidity is the chief factor contributing to inhibition and
death of the streptococcus in glucose broth cultures. This is
evidenced by the fact that growth proceeds luxuriantly in fil-
trates from active cultures the acidity of which has been neu-
traUzed by a base.
13. At a Pb of 5.25 lactic and acetic acids appear to have
about equal disinfecting powers for Streptococcus hemolyticua.
Organisms* live for longer periods in filtrates from active cultures
than in broth brought to the same Ph with either lactic or acetic
acids.
14. A marked increase in tolerance for acid is shown by
streptococci in the presence of horse serum. In one test it was
found that viability persisted for a period nearly four times as
long in serum-glucose broth of Pb 5.20 as was evident in glucose
broth adjusted to the same Ph.
THE BIOCHEMISTRY OF STREPTOCOCCUS
HEMOLYTICUS
LAURENCE F. FOSTER
From the DepartmerU of Pathology and Bacteriology, University of California
Received for publication August 15, 1920
I. THE ACIDS PRODUCED BY STREPTOCOCCUS HEMOLYTICUS*
The cessation of activity in a glucose broth culture of Strepto-
coccus hemolyticus comes when a fairly constant point of hydro-
gen-ion concentration is reached. This change is caused by a
fermentation of the medium with a resultant formation of acid
substances. The present section of this paper has to do with
the chemical nature of these acid products.
A review of the literature reveals the fact that scant attention
has been paid to the biochemistry of bacterial fermentations.
Emmerling (1896), in 1896, carried out determinations of acids
obtained from the putrefaction of certain proteins through the
action of Proteus and Staphylococciis pyogenes. Tissier and
Martelly (1902) in a study of the putrefaction of meat foimd that
Streptococcus pyogenes could only split natural proteins after the
latter had been peptonized. The same organism rapidly attacked
glucose forming, chiefly, lactic acid. Clostridium wehhii and C.
sporogenes were found to produce acid and alkaline substances si-
multaneously. Later work by Wolf and Telfer (1917) upon these
last-mentioned organisms has shown that a large proportion of the
acid formed in their fermentations is volatile in character. The
method of Dyer (1916) was employed by these investigators in
determining the volatile acids. Forty per cent of the total acid
produced by the organisms mentioned proved to be non-volatile.
The exact chemical nature of this fraction was not determined.
^ Miss Bemice Rhodes rendered valuable assistance in carrying out the experi-
mental work described in this section of the paper.
211
212 LAURENCE F. FOSTER
•
In a study of the dcid fermentation of xylose by Fred, Peterson,
and Davenport (1919) the main products were found to be acetic
acid and lactic acid. The proportion of volatile acid to non-
volatile acid proved to be the same throughout the entire ten
to twelve days of fermentation; namely, 40 per cent of acetic
to 60 per cent of lactic acid. The two acids represented about
90 per cent of the sugar consimied.
Speakman (1920) investigated the biochemistry of acetone
and butyl alcohol fermentation of starch and showed that acetic
and butyric acids are formed as intermediate products. A
reduction of these acids to the corresponding alcohol subse-
quently sets in.
Methods
Volatile acids. Volatile acids were determined by the steam
distillation method of Duclaux (1900) as modified by Dyer (1916).
This procedure is one in which the acid solution is distilled with
steam at a constant volume. The distillate is collected in 10 cc.
fractions until 100 cc. have passed over, after which the remainder
is taken off in 100 cc. portions. These fractions are then titrated
with n/50 alkali, using phenolphthalein as indicator, and the
percentage of acid is calculated. The amount of acid in a given
fraction, the "distilling constant" for the fraction, is plotted
against the corresponding portion of distillate on logarithmic
coordinate paper. Pure acids are graphically represented as
straight lines and arrange themselves consecutively from the
lower to the higher members of the series. With a mixtiu^ of
two volatile acids the first part of the curve occupies a position
intermediate to the lines representing the distilling rates of the
higher and lower boiling acids. As the higher boiling acid is
removed, the curve gradually becomes parallel with the line
representing the lower boiling acid.
It follows that the distillate from an unknown acid mixture
may be approximately determined by plotting a curve from the
distilling constants and comparing this with the curves estab-
lished for known acids.
BIOCHEMISTRY OF STREPTOCOCCUS HEMOLYTICUS
213
The apparatus employed differed from that of Dyer (1916)
in that the heating of the flasks was done with gas instead of
electricity. By thoroughly insulating the flasks and connecting
tubes with asbestos it was possible to maintain a constant volume
throughout a long distillation.
To test the accuracy of the method several preliminary deter-
minations of pure acids were first carried out. The results
obtained for formic, acetic, and caproic acids are to be foimd in
TABLE 1
Distilling constants {pure adds)
FBACriON
rOBMIO AOZD
Aoanc ACID
m
CAPHOXO AGIO
ee.
10
2.0
4.66
24.55
10
3.8
9.45
43.85
10
5.5
14.17
58.83
10
7.5
18.93
70.25
10
9.8
23.57
78.30
10
12.0
28.16
83.90
10
14.0
32.59
88.16
10
16.4
36.91
91.46
10
19.0
41.19
93.90
10
21.2
45.24
95.74
100
35.6
71.89
99.22
100
52.4
89.60
99.95
100
63.5
99.49
table 1. Graphical representation of the distilling rates has
been made on logarithmic coordinate paper (see fig. 1). The
curves were found to fall between those of Dyer and those of
Wolf and TeKer. Attempts to use the color tests suggested by
Dyer did not meet with success and accordingly they were
abandoned.
Lactic add. It was presumed that the non-volatile portion
of the cultures consisted mainly of lactic acid; therefore the fol-
lowing quantitative method suggested by Fred, Peterson, and
Davenport (1919) was employed for its determinations:
The residue from the distillation flask was carefully evaporated
on a hot plate to a volume of about 40 cc. This was placed in a
Soxhlet extractor and extracted with ether for fifty to sixty hours
214
LAURENCE F. FOSTER
to remove the lactic acid. About 30 cc. of water were added to
the ether extract and the ether removed by distillation. The
water extract remaining was then titrated with n/10 Ba(OH)s
adding a 5 cc. excess of the base. The material was boiled for
fifteen minutes to convert all of the lactic kcid to the barium
salt, after which the excess of Ba(0H)2 was removed by neutrali-
zation with HsS04. This mixture was allowed to stand for
several hours on a steam bath, filtered, and the filtrate and
90
00 7Q « SI«SiaDO
%0cid
Fig. 1
washings evaporated to dryness. After taking up the residue
with water the material was again filtered to remove traces of
organic matter or carbonates. The filtrate was then made up
to a definite volume (50 or 100 cc.) and a 10 or 20 cc. aliquot
taken for analysis. A test for succinic acid was made at this
point by adding to the aliquot sufficient 95 per cent alcohol to
bring the volimie to 100 cc. Succinic acid, if present, gives a
precipitate, and the material must be filtered. The filtrate was
again evaporated to dryness and the residue taken up in 60 per
BIOCHEMISTBT OF 8TRBPTOCOCCT78 HEMOLTTICU8 215
•
emit alcohol. This alcoholic solution was carefully evaporated
to dr3mess in a tared dish and dried at 130^0. to a constant
weight. An excess of HsS04 was next added and the material
converted to BaS04 by ignition. From the weight of BaS04
obtained, the corresponding weight of lactic acid was readily
calculated. In case lactic is the only acid present the theoretical
yield of BaSO^ may be estimated from the weight of dried barium
salt previously found.
ExperimerU I. The volatile and nonrvolatile adds produced in
streptococcus fermentations
One hundred and fifty cubic centimeters of broth were inocu-
lated with 6 cc. of a first-generation, glucose broth culture of
Streptococcus hemolyticus and incubated for eighteen to twenty-
four hours. Determinations of the volatile and non-volatile
acids were made upon 100 cc. of this cultiu*e in the manner
described. Control determinations were carried out upon a
sample of xminoculated broth. The following results were
obtained:
Adds Brca
Volatile (as co. of n/10 acid per 100 ce. broth) 4.42
Lactic acid (as grams per 100 cc. broth) 0.031
The values shown in the table were applied as corrections in
the analyses of cultures.
Of the numerous estimations which have been made the results
of but three will be presented: Culture (1), 1 per cent glucose
broth; culture (2), 1 per cent glucose broth; culture (3), 1 per
cent glucose, 5 per cent horse serum broth.
The curves plotted from the ''distilling constants" (shown in
table 2) proved to be so closely analogous that only one result
will be shown. From the position of the line (fig. 1) representing
the distilling rate of culture (1) it would appear that acetic acid,
chiefly, is elaborated by the streptococcus during its growth in
broth media containing either glucose or glucose plus horse serum.
A trace of formic acid may also be present. This conclusion is
the only one that may be drawn at present even though the
JOUBMAIi CMP BAOrBBtObOOT, TOIL. YI, NO. 2
216
LAUBENCE F. FOSTEB
curve is not typical of a mixture of two volatile acids. No
attempt has been made to re-fractionate the distillates, conse-
quently the percentage of each acid in the volatile portion is not
known. Reference to table 3 indicates that no close agreement
exists between the per cents of volatile acid from culture (1)
and culture (2) though the same lot of broth was used in each
and the fermentation apparently progressed to the same point
as the final Ph of the cultures was practically equal. Culture
(3) gave a fraction of volatile acid still smaller than was noted
in the other cases.
TABLE a
Exp€Ttmcnt I
FKAOTIOir
oui;ruBB (1)
OX7Iin7BK(2)
OUXffUBB (8)
ee.
10
4.50
5.32
3.45
10
9.00
9.06
7.13
10
13.81
12.07
10.58
10
18.68
15.71
13.32
10
23.83
18.50
16.01
10
28.06
21.82
18.69
10
32.63
24.61
21 :8
10
35.84
27.62
24.07
10
39.26
30.10
27.05
10
42.14
32.36
30.26
100
61.19
59.40
60.06
100
77.32
77.62
76.56
100
93.45
91.17
88 26
100
99.80
100.90
ilJtI. vD
The lactic acid estimations in the two glucose broth cultures
do not correspond especially well and the value obtained in
culture (3) is smaller than would be expected.
Throu^ a lack of time it has been impossible to carry the
present phase of the investigation to a logical completion. As
a consequence it will be inadvisable to draw other than very
general conclusions from the data presented.
It may be concluded from results that are to be presented
later that in a 1 per cent ^ucose broth culture of the strepto-
coccus some 156 mgm. of glucose are utilized in the first twelve
to eighteen hours. From the data shown in table 3 it is possible
BIOCHEMISTRT OF STREPTOCOCCUS HEMOLYTICUS
217
to calculate the amount of glucose destroyed in the formation
of the acids. Assuming for the moment that the volatile fraction
consists entirely of acetic acid and the non-volatile fraction of
lactic acid, a calculation indicates that the total acidity of this
culture accoimts for only 50 per cent of the glucose utilized.
Fred, Peterson, and Davenport (1919) were able in" this way to
account for 90 per cent of the sugar utilized in their xylose
fermentations. The large discrepancy in the present experiment
may possibly be due to two factors, first to experimental error,
and second to the fact that another imknown non-volatile acid
is present in the fermentation mixtures.
TABLES
ExpcTitncrU I
OULTXTBI
Pr
TOLA-
TILK
Aca>
(N/10
ACID
PKB
100 00.)
LACrrO AOID
▼OLA-
TILB
ACID
i
m
Initial
Fmal
Per
100 CO.
N/IO
acid per
100 oe.
LAcno
ACID
1
2
3
Glucose broth
Glucose broth
Glucose serum broth
1
7.4
7.4
7.4
5.3 (18 hrs.)
5.4 (18 hrs.)
4.9 (24 hrs.)
ee.
1.196
2.98
2.68
granu
0.061
0.0725
0.0634
ee.
6.78
8.05
5.25
per eeni
15.0
27.1
33.8
per cent
85.0
72.9
66.2
II. THE METABOLISM OF STREPTOCOCCUS HEMOLYTICUS
Within the past few years evidence has been increasing which
indicates that bacterial metabolism and human cellular metabol-
ism have certain fundamental characteristics in common. We
are indebted principally to Kendall and his collaborators for our
more definite knowledge of the chemical activities of unicellular
organisms. Cellular metabolism consists of two distinct phases —
(1) the anabolic or structural phase, (2) the katabolic, destructive
or ''fuel" phase. As 'in the case of man, bacteria obtain struc-
tural material from nitrogenous nutrients while the energy
requirements are best satisfied by carbohydrate substances. The
analogy may be extended farther to the well known physiological
principle that "Carbohydrates spare body nitrogen." In other
words, those bacteria which are capable of utilizing both carbo^
218 LAUBENCE F. FOSTEB
hydrate and protein for katabolic purposes will attack the former
m preference to the latter (Kendall and Farmer, 1912a, 1912b).
This phenomenon, which has been established by Kendall and
his associates as a fundamental principle of bacterial metabolism,
may be eicpressed concisely, according to Kendall and Farmer
(1912d) in the statement that, ''Fermentation takes precedence
over putrefaction." These authors define fermentation as, ''The
action of microorganisms upon carbohydrates, putrefaction as
the action of microorganisms upon nitrogenous substances."
They state further that "The products of proteolytic activity,
which are only formed when bacteria are utilizing protein for
fuel are alkaline nitrogenous substances; the products of fermen-
tation, on the contrary, which are formed when bacteria are
utilizing carbohydrates for fuel, are non-nitrogenous, acid
products."
Inasmuch as nitrogen is the most important structural el^nent
entering into the composition of the cell, a quantitative measure
of nitrogen degradation must form a very important step in the
study of cellular metabolism. In man, nitrogenous waste is
excreted from the body mainly as urea, but with bacteria, which
are known to excrete nitrogen principally as ammonia, urea, if
formed at all, would represent a product of intermediary meta-
bolism. This theory is borne out by the fact that certam bacteria
are able actually to utilize urea.
Kendall and his associates (1913) have concluded after many
studies upon a variety of organisms that ammonia formation,
representing the final step in the degradation of proteins andprotein
derivatives, is the best available index of proteolysis by bacteria.
Ammonia formation is considered by Kendall and Walker (1915)
to result from intracellular deaminization of assimilated protein
derivatives, incidental to their transformation into energy.
Kendall, Day, and Walker (1913a) have estimated that the
amoimt of protein needed for structiu*al purposes by the bacterial
cell is in all probabiUty exceeded by the amoimt wasted through
excretion. The combined structural needs and structural waste
are much less than the fuel needs and the fuel waste. Further,
the fuel requirements only cease upon the death of the organism,
BIOCHEMISTRY OF STREPTOCOCCUS HEMOLTTICUS 219
whereas the structural needs are practically complete when the
cell attains its morphological maturity. Consequently the fuel
requirement is one of comparatively long duration. According
to the saine authors, a rapid disintegration of fuel materials
occurs in the case of saprophytic bacteria. In other words, stich
microorganisms must, in general, be considered more active
chemically than are pathogenic bacteria.
In the experiments conducted with the streptococcus it has
been noted that growth in vitro is always accompanied by elabor-
ation of acid products through the fermentation of materials of
carbohydrate nature. No medium has ever been used which
does not respond to the fermentative activities of this organism.
Kendall, Day, and Walker (1913b) state that when bacteria
are metabolizing carbohydrate the nitrogen requirement is
minimal, so that in glucose broth cultures of Streptococcus hemo-
lyticus we would expect the katabolic or "fuel" phase to pre-
dominate over the anabolic or structural phase of metabolism.
Moreover, the presence of horse serum in broth was found to
exercise a decided stimulatory effect upon growth rate and acid
formation, and also proved effective in permitting growth through-
out a wider range of hydrogen-ion concentration. From a con-
sideration of the fimdamental features of bacterial metabolism
as outlined in the foregoing discussion, it would seem obyious
that these phenomena represent a stimulated metabolism of the
organisms brought about through some property of the senun.
It was suggested previously that structural or growth-accessory
substances are perhaps furnished by this material thus permitting
the organisms to inaugurate their metabolic activities earlier
with consequent reduction of lag. This theory would be in
accord with the statement of Kendall, Day, and Walker (1913b)
that the structural function always precedes the vegetative or
fuel function chronologically, inasmuch as the cell must be
formed before it can carry on its appropriate activities.
The following experiments represent an attempt to study the
metabolism of the streptococcus in various culture media with
an especial effort to determine whether correlation exists between
the rates of acid formation and the rates of other metabolic
processes in (1) glucose broth, and in (2) glucose-serum broth.
220 LAURENCE F. FOSTER
Methods
Ammonia was determined by the Folin air current method
(1912) using 2 cc. of culture and collecting the gas in ^/50 acid
after which the residual acid was determined by back titration
with n/50 base. Results are expressed as milligrams per 100
cc. of cultiu*e.
Amino acids were determined by the f ormol titration method
of Sorensen previously described (see section I) .
Glucose was determined by the method of Bertrand (Hawk,
1918). As the presence of peptone and protein material in the
medium rendered the application of the method impossible, the
following procedure, devised by Dr. Marjorie W. Cook, was
employed to free the cultures from interfering substances:
Twenty cubic centimeters of culture was diluted to 100 cc.
with distilled water and precipitated with 10 to 15 cc. of saturated
tannic acid solution. After filtering, 5 to 7 grams of lead acetate
were added to the filtrate to remove excess of tannic acid and
this mixture was filtered. If the filtrate was turbid more lead
acetate was added. To the filtrate from this treatment was
added 2 to 3 grams of sodium oxalate. This removed the lead
as Pb(Ci04). The filtrate from this last treatment should be
perfectly clear and colorless. It is important throughout the
whole procedure to keep the containers and funnels covered thus
minimizing evaporation and reducing the error from this soiu*ce.
Two 10 cc. portions of this liquid were now used for determina-
tions of glucose.
Bacterial coimts were made by the method of Wright and
logarithms of the values so obtained were employed in plottmg
growth curves. It must be borne in mind that the method
of Wright gives only approximate results and that the values
represent the total number of organisms rather than the number
of viable cells.
Titrations of hemotoxin were made with sterile tubes, pipettes,
etc., to maintain the purity of the streptococcus cultures. Rab-
bit corpuscles which had been washed three times in 0.85 per
cent NaCl and made up in a 1 per cent suspension in beef infusion
BIOCHEMISTRY OF STREPTOCOCCUS HEMOLTTICtTS
221
broth were used in the tests. To 0.5 cc. of the corpuscular
suspension were added amounts of culture varying from 0.005
cc. to 0.5 cc. The volume was then made up to a total of 1 cc.
with broth, after which the mixture was incubated at 37® for
two hours. During the first hour of incubation the tubes were
frequently shaken to insure thorough mixing. At the end of
the incubation period the degree of hemolysis was observed,
and expressed as follows:
100 per cent of corpuscles hemolyzed ++++
90 per cent of corpuscles hemolyzed +H-+±
75 per cent of corpuscles hemolyzed +++
50 per cent of corpuscles hemolysed ++
25 per cent of corpuscles hemolysed +
0 per cent of corpuscles hemolysed —
Experiment II. The "protein eparing^^ action of Streptococcus
hemolyticus
Bacto beef broth, Ph 7.2, served as the basis of the combina-
tions used in the experiment. The inoculum for each 10 cc. of
broth consisted of 0.4 cc. of an eighteen-hour, glucose broth
culture. The ammonia determinations were made after seventy
hours incubation. The results are incorporated in table 4.
TABLE 4
Experiment II
NUICBBB
BBBUM
GLUCOflB
rBBll NHs AS MOM.
N PBB 100 oc. (axnjrxjME)
WMMM NHa AM MOM.
N PSB 100 00. (COITTBOL)
fMretnt
percent
1
—
—
9.80
9.73
2
5
—
13.02
8.55
3
—
1.0
9.25
7.85
4
—
0.1
10.22
7.00
5
—
0.3
9.95
8.00
6
5
1.0
9.95
8.68
The results show that in the presence of little or no free carbo-
hydrate, as in (2) and (4) of the table, the ammonia output is
slightly increased over that found in the presence of 1 per cent
glucose. If protein material in the form of horse serum be
present the ammonia output is distinctly higher. This is shown
222 LAURENCE F. FOSTER
in (2). When the 5 per cent horse serum is in the presence of
1 per cent ghicose, however, no increase in NH| is manifest
((6) in the table) showing that the sugar shields the protein from
attack in this instance.
Experiment III. The protein and carbohydrate metabolism of
Streptococcus hemolyticue in broth corUaining (1) glvcoae
and {£) glucose phis horse-serum*
Three hundred cubic centimeter lots of media of the following
composition were prepared from beef infusion broth, Ph 7.3:
(1) 1 per cent glucose broth; (2) 1 per cent glucose, 5 per cent
horse serum broth; (3) same as (2).
(1) and (2) were inoculated with 12 cc. of an eighteen-hom*,
second-generation culture from pleural fluid no. 198 in 1 per
cent glucose-broth. (3) was inoculated with an equal amount
of an eighteen-hour, first generation culture of the so-called
laboratory strain. This culture differs from the pleiural fluid
culture in that it has been repeatedly transplanted upon artificial
culture media since the original isolation, whereas the latter has
been passed many times through rabbits. Both cultiu*es were
carried in this experiment in order to determine if repeated
transplantation upon artificial culture media had brought about
changes in the strain which might appear as an alteration of some
phase of its metabolism.
The following determinations were carried out upon samples
removed with aseptic precautions at intervals of three hours:
(1) Bacterial counts; (2) Ph; (3) glucose; (4) ammonia; (5)
amino acids; (6) hemotoxin.
The experiment extended through a period of twelve hours.
Table 5 contains the experimental data.
The curves of growth, acid' formation and glucose utilization
in the three cultures are found in figures 2, 3, and 4. It will be
' The writer desires to express his appreciation for the assistance rendered
by Dr. Marjorie W. Cook and Miss Bemice Rhodes in carrying out this
experiment.
* The term acid is used to express true acidity in terms of Ph.
BIOCHEMI8TRT OF STKEFTOCOCCtTB HEMOLYTICUB
noted that although a rough parallelism between these factors
is shown in the three curves of each culture it is most striking
in the pleural fluid culture (fig. 3). Here, particularly in the
maximmn period, may be seen a close relationship between the
curves of growth, acid formation, and glucose utilization. A
correspondence of the three factors in the maximmn period
TABLES
Experiment III
BACTIBIAIt COUMT
Per on. mm.
Loc
Ph
CBt17C06B
100 00.
UtUiMd
NHi.
MQM. N
PBB
100 oc.
▲ICXMO
ACIM.
MOM. N
100 00.
(1) 1 per cent glucose broth (pleural fluid no. 196)
grnwu
fNom.
0
16,400
4.21
7.30
1.093
0
6.01
18.87
0
3
50,700
4.71
7.20
1.172
0
5.73
19.07
0
6
960,000
5.96
6.40
1.007
89
6.57
17.73
purple
9
1,140,000
6.06
5.76
0.955
141
9.93
17.57
+++
12
1,700,000
6.23
6.55
0.935
161
9.79
19.51
0
(2) 1 per cent glucose, 5 per cent horse-serum broth (pleural fluid no. 196)
0
23,800
4.38
7.35
1.096
0
5.03
19.77
0
3
90,200
4.96
7.20
1.068
28
6.29
18.21
0
6
2,000,000
6.30
5.80
0.941
155
9.93
16.87
++++
9
3,500,000
6.54
5.10
0.877
219
10.49
19.41
++++
12
4,560,000
6.65
4.90
0.847
249
10.07
20.73
0
(3) 1 per cent gucose 5 per cent horse-serum (Laboratory strain)
0
40,000
4.60
7.35
0.992
0
6.43
19.17
0
3
90,400
4.96
7.20
1.001
0
5.45
20.95
0
6
1,456,000
6.16
5.90
0.862
130
8.67
18.03
++++
9
2,860,000
6.46
4.95
0.722
270
8.25
20.55
++++
12
4,700,000
6.67
4.90
0.728
270
7.69
20.61
0
appears in the other two cultures as well, though it is less striking.
In each case it will be observed that a rise in the acidity curve
is preceded by a rise in the growth curve. Attention should be
directed to the fact that while acid production proceeds most
rapidly during the time when the organisms are multipl3ang
at a maximum rate, nevertheless, a considerable lowering of
224
LAURENCE F. FOSTER
Pb occurs during the succeeding period when the cells are increa^
ing at a diminishing rate. Stated differently, the curves of
growth in each culture depress more sharply from the mayiTmiTn
period than do the ciurves of glucose utilization and acid for-
mation. Reference to table 5 shows that hemotoxin production
commenced in the serum cultures by the sixth hour and persisted
a/
3 € 9 H.m^9
Fio. 2. ExpBRiMBNT III. Cui/TtJBE (1); 1 Pbb Cbnt Glucobb Bboth
for at least three hours. In the glucose culture however, no
definite appearance of hemotoxin was evident until the ninth
hour. In each case hemotoxin appears in the period character-
ized by growth and acid formation at decreasing rates.
Reference to figures 5, 6, and 7 indicates that ammonia pro-
duction was imdergoing a definite increase by the third hour in
each of the cultiu*es. This increase in the serum cultures (figs.
BIOCHEMIBTRT OF STREPTOCOCCUS HBMOLYTICUS
925
6 and 7) was greatest between the third and the sixth hours
while in the glucose culture (fig. 5) it was largest between the
sixth and the ninth hours. The increase in ammonia output in
a general way parallels growth and acid formation during the
maximum period in each case. Associated with this increase
$ € 9 Houts
Fio. 3. ExpEBiMBNT III. CxTunTBB (2) ; 1 PxR CsNT Glucoss, 5 Pbb Cbnt Hobsb
Sbrum Bboth (Pleubal Fluid Stbain)
in the output of anunonia a coincident decrease in amino acid
production is evident. In the serum cultures the curves of
amino acid output rise sharply at the sixth hour while in the
glucose culture the rise is delayed imtil the ninth hour. The
initiation of this rise appears to be in direct correlation with a
high point of the ammonia curve.
226
lAUBENCE F. FOSTER
From tiw rosultB of this Bxpetiweot it 000010 evJdcBt ABt acid
formatioii is closely associated chronologically with growth and
active metabolism of the streptococcus. In each of the three
cultures we find the maximum period of acid production corre-
lated with maximum rates of growth, and of glucose utilization.
These results are not in accordance with the findings on pneu-
Hi
AA
5X
Oi^a^
Fig. 4. Expbbimekt III. Gui/tubb (3) ; 1 Per Cbnt Glttcosb, 6 Pbr Gbnt Hobsb
Serum Broth (Laboratory Strain)
mococci by H. M. Jones (1920) who reported a maximum period of
growth correlated with slow acid formation, whereas the maxi-
mimi period of acid production occurred during the time when
the organisms were multiplymg at a diminishing rate.
In a study of the nitrogen metabolism of actinomycetes,
Waksman (1920) concluded that the production of amino acids
BI0CHEMI8TRT OT STBEPTOCOCCTTS HEMOLTnCUS
227
is not a waste process resulting from growth but that it represents
a definite step in the metabolism of the organisms. In his
experiments amino acids did not acciunulate in the mediiun
until after the organism had made its growth. In explanation
Waksman suggests two possibilities; either (1) the growing
cells utilized the amino acids as rapidly as the latter were formed,
(imf fmr iOOmf
II
lO
21
19
ZO
19
/a
n
3 6 9 Hoytj
Fig. 5. Expbbiment III; Culture (1); 1 Pbr Cent Glucose Broth
or (2) the proteolytic enzyme necessary for their elaboration
api)eared only in the later stages of growth. Attention has been
called to the fact that the curves of amino acid formation in
experiment III exhibit a rise at the sixth or the ninth hour which
would correspond to the findings of Waksman on the actino-
mycetes. Examination of the growth curves (figs. 2, 3, 4) at
tins point shows that the maximiun period has just been |)assed
and that the organisms are now multiplying at a diminishing
228
LAURENCE F. FOSTEB
rate. As a consequence the amino acid intake of the cells is
reduced to a low level. This would account for the increased
output in the medium. It has been pointed out that the rise
in ammonia production in each culture, starting at the third
hour, is correlated with a drop in the amino acid curve (figs.
5; 6, 7). The most probable explanation of this finding rests
n
to
zz
II
20
19
/•
Fio. 6. ExpBRiioBNT III. Culture (2) ; 1 Pbr Cent Glucose, 5 Per Gbkt
Horse Serum Broth (Pleural Fluid Strain)
upon the supposition that dtiring the early life of the culture
amino acids are utilized by the cells for structural purposes thus
reducing their concentration in the mediiun. As more amino
acid nitrogen is assimilated, a larger amount of ammonia is
split off intracellularly. This is evidenced by a rise in the curves
of ammonia production during this period. Such an hypothesis
is in accord with the theory of Kendall and Walker (1915) that
BIOCHXMISTRT OF STBBFTOCOCCXTS HSMOLTTICXXS
229
ammonia formation is the result of intracellular deaminization
of assimilated protein material.
Wolf and Harris (1917b) in their study of the biochemistry of
Cloatridtum welchii and C. sporogenea noted in cultures grown in a
medium of high amino acid content that at the close of the experi-
ment the concentration of amino acids was less than at the b^pn-
(mq. rw too €c)
//
10
22
6
Zl
zo
19
/a
/7
16
Hours
Fig. 7. Expebimbnt III. Culture (3) ; 1 Peb Cent Glucose, 5 Feb Cent Hobsb
Sebum Bboth (Labobatobt Stbain)
ning. This indicates that these substances were assimilated by
the growing organisms and destroyed through deaminization.
Reference to figures 6 and 7 reveals a very decided difference
in nitrogen metabolism in the two serum cultures during the
initial three-hour period. The pleiu*al fluid culture exhibited a
definite decrease in amino acid output correlated with an increased
230 LAUBBNCE F. F08TBB
ammonia fonnation, whereas the laboratory culture showed a
decided increase in amino acid output coupled with a slight
decrease in ammonia excretion. Whether or not this deviation
represents a permanently altered aspect of metabolism .on the
part of the laboratory strain must for the present remain un-
decided. It may be that through continued cultivation upon
artificial media the organism has gained the ability to inaugurate
proteolysis earlier. Such a conclusion would be opposed to
the finding of Rosenthal and Patai (1914) that avirulent strepto-
cocci were less strongly proteoljrtic than cultures of the same
strain the virulence of which had been increased by animal
passage. In the present experiment the curves of nitrogen
metabolism (figs. 6 and 7) show the same general features from
the third hour to the end of the period of observation. No
differences in the growth, acid formation, or glucose utilization
were evident in the two cultures throughout the entire period
of the experiment.
STTMMART AND CONCLUSIONS
1. Lactic acid appears to be the principal acid formed by
Streptococcus hemolyticiLs in its fermentation of glucose broth.
A smaller proportion of volatile acids is formed. This fraction
is made up chiefly of acetic, with perhaps a trace of formic acid.
2. A quantitative study of the ammonia excretion of the
streptococcus indicates that a ''protein sparing" action occurs
in media containing available sugar to meet the energy require-
ment of the developing cells.
3. The maximiun periods of glucose utilization and acid
formation in glucose and in glucose-serum broth are correlated
with growth at a maximiun rate, though a considerable lowering of
Ph occurs during the period when growth proceeds at a diminish-
ing rate.
4. The greatest increase in output of ammonia is correlated
in a general way with the maximmn periods of growth, glucose
utilization, and acid formation. Associated with this increased
•output of ammonia a corresponding decrease in amino acids is
evident. This condition seems to be associated with the interval
BIOCHEMISTRY OF BTREPTOCOCCUS HEMOLTTICXJS 231
in which the organisms are making their growth. During this
period, in which it may be presumed that anabolic processes
are actively under way, the organisms are utilizing amino acids
for structural purposes. This would cause the latter to decrease
in concentration in the medium and furthermore would produce
an increased excretion of ammonia through the katabolism of a
part of the absorbed amino acids.
5. Subsequent to the period in which the organisms have made
their growth a rise in the curves of amino acid formation is mani-
fest. In the cultures containing horse serum 'this rise is initiated
by the sixth hour; in the glucose culture it appears by the ninth
hour. A decrease in ammonia output, in general, accompanies
the rise in amino acid formation. These findings indicate that
a decreased utilization of nitrogenous materials ensues after the
organism has passed its maximum period of growth, despite the
fact that proteolysis continues.
6. A marked difiference in nitrogen metabolism between a
passage strain and a laboratory strain of Streptococcus hemolyticua
is noted during the first three hours of incubation in glucose
serum broth. Whereas the passage strain shows a definite
decrease in amino acid output coupled with an increased am-
monia excretion, the laboratory strain exhibits a decided increase
in amino acid output coincident with a slight decrease in am-
monia formation. Whether or not this represents a permanent
deviation in metabolism resulting from continued transplantation
upon artificial culture media is a question that for the present
must remain undecided.
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234 LAUBENCE F. FOSTER
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• tKIH I .
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236 LAURENCE F. FOSTER
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NOTES ON THE FLAGELLATION OF THE NODULE
BACTERIA OF LEGUMINOSAE
IVAN V. SHUNK
DepcaimerU of Botany, North Carolina State College
Received for publication August 29, 1920
For many years it has been known that the nodule bacteria
of Leguminosae are motile. Some early reports give the number
of flageUa as one, other reports describe several. From time
to time some addition has been made to our knowledge of the
flagellation of these, organisms*. Since the information on this
point has been rather fragmentary and somewhat imcertain,
the writer began the study of the flagellation of the nodule
bacteria from a considerable number of host plants in the spring
of 1920.
Different workers, using bacteria from different host plants,
have found in some cases a single flagellum aixd in other cases
several peritrichic flagella, and in a number of instances it has'
been assumed because the ones under observation were of a
certain type, that therefore all nodule bacteria were similar to
the ones studied. • This point together with the general paucity
of information on the flagellation of legume bacteria is well
brought out by the following brief historical review of all avail-
able published reports.
Smith (1900) reported a single terminal flagellum about two
p. long bearing at the end a tuft like the lash of a whip. He does
not state the source of his organism.
DeRossi (1907) found a single flagellum on organisms from
Vicia faba. He later (1920) reported the organism to be a true
Bacillus with several flagella, but it is not clear from his accoimt
what host plants furnished the bacteria except that Trifolium
repens was one of those used.
239
240 IVAN V. SHUNK .
Harrison and Barlow (1907) reported a single polar flagellnm
on the organisms from Lathyrus aativus and Vicia viUosa but
their method of staining was such that only the slime and muci-
lage around the bacteria were stained, leaving the bacteria
themselves unstained.
Zipfel (1912) reported nimierous peritrichic flagella, but did
not state the source of his organisms.
Kellerman (1912) reported numerous peritrichic flagella on
the organisms from Phaseolua lunatus, Medicago sativa and Pisum
saiivum.
Burrill and Hansen (1917) have given us the most extensive
information on the question of the fls^ellation of this group.
They reported a single flagellum on organisms from Vigna sinensis^
Glycine hispida, Acacia flaribunda, Arachis hypogoea, BapHsia
tinctoriay Genista tinctoria, Cassia chaemacrista, Amphicarpa
monoica, Lespedeza striata, Desmodium canescens, and Miuruna
vtilis.
Fred (1918) has found on the alfalfa organism several peri-
trichic flagella and on the lupine organism one or rarely two.
Prucha (1915) has found several flagella on the organism from
the Canada field pea.
Wilson (1917) reported as many as four flagella on the soy
bean organism.
Hansen (1919) has found peritrichic flagella on the organisms
from Trifolium pratense, Vicia viUosa, and Melilotus alba.
Much of the difficulty in staining the flagella of these bacteria
has been and still is due to the amount of slime that is produced
by these organisms. Some produce slime more abimdantly
than others, and in some cases the mass of bacteria is so viscid
that it may be drawn out in a string in making transfers.
METHOD OF ISOLATION
The roots of various leguminous plants were dug and carefully
washed in running tap water. SmaU pieces of roots bearing
nodules were then removed leaving enough root attached to aid
in handling. These nodules were allowed to stand in tap water
FLAGELLATION OF BACTERIA OF LEOUMINOSAE 241
for a few minutes after washing. With a pair of forceps a nodule
was then placed in a disinfecting solution prepared by adding
2.5 cc. of concentrated hydrochloric acid to 500 cc. of a 1:500
corrosive sublimate solution and allowed to remain in this solution
for one and a half to two minutes. It was then removed with a
pair of flamed forceps, rinsed in sterile tap water, and placed in
a drop or two of sterile tap water in the center of a sterile Petri
dish. The nodule was crushed by using a flamed and cooled
glass rod, after which a tube of sucrose agar which had been
melted and properly cooled was added, and thoroughly mixed.
The sucrose medium just referred to was made as follows:
Monobasic potasBium phosphate 1.0 gram
. Magnesium sulphate 0.5 gram
Sucrose 10.0 grams
Tapwater 1000.0 cc.
Agar 10.0 or 15.0 grams
At first no attempt was made to adjust reaction, but as the
growth on this medium was so slow most of the media used were
adjusted to pH 7.0-7.4 using the colorimetric method.
Several plates were made at each time, thus insuring good
distribution of colonies in at least one of the plates. All plates
^ were kept at room temperatures. After the colonies developed
transfers were made either to the same sucrose mediiun or to a
similar medium, containing 10 grams of mannitol in place of the
sucrose. The mannitol media were used almost exclusively
for maintahiing the organisms after transfer from the isolation
plates.
METHOD OP STAINING FLAGELLA
The staining method used was a modification of Loeffler's
flagella stain suggested by the writer in a previous paper (1920).
Bacteria from a slant on mannitol or sucrose agar were removed
and placed in a small quantity of sterile tap water in a test tube.
Several small droplets of this suspension were, after a few minutes,
placed on a well cleaned cover glass and allowed to air dry.
About five drops of Mordant solution A were placed on the cover
glass as soon as the droplets had dried, and this was followed
242 IVAN V. SHUNK
immediately by one or two drops of solution B. The combination
was allowed to act at room temperature for two minutes, washed
in distilled water and the stain applied for two minutes. The
excess stam was washed off with water and the cover glass prepa-
ration dried and mounted in balsam.
RESULTS OF STAINING
The age of cultures of the organism from different legume
host plants made a considerable difference in the staining reaction.
It was sometimes necessary on this account to try cultures of
varying ages before successfully staining the flagella. The fol-
lowing table contains the data bearing on the source of the cul-
tures, their age at time of staining, and the number of flagella.
DISCUSSION
Manifestly the flagellation of the legume nodule bacteria is
of two types, the single flagellate type and the peritrichic. In
every case in which the organisms possessed more than one
flagellum the arragement was peritrichic and in the case of those
with a single flagellum it was usually attached at the comer
rather than exactly at the end. This comer arrangement seems
to characterize the single flagellate type. In the case of organ-
isms of this type, more than one flagelliun was never found, and
enough organisms were observed in each case so that there is no
doubt that one is the correct number, and that it is an entirely
different organism from the peritrichic type. Due to the break-
ing off of flagella in handling, bacteria of the peritrichic tyi)e
showed an occasional organism with only one flagellimi. For
the most part the peritrichic flagella were longer than the single
flagella and there was a tendency for the sin^e flagella to be of
greater diameter than those of the other type.
The present findings are in accord with those of Hansen (1919)
who has suggested that since the organisms from different
legumes have in some cases one flagellum, and in others several
flagella, we have really two groups of organisms based on these
differences of flagellation. Conn (1920) is of the opinion that the
FLAGELLATION OF BACTBRLA OF LEGUMINOSAE
243
TABLE 1
FlageUiUion of legume nodide bacteria
tionvLAsn
Vicia anguetifolia (smaller common vetch)
Vicia dasycarpa.(yeieh)
Vicia hireuia (tineweed or vetch)
Vicia alba (vetch)
Vicia saliva (common vetch)
Vicia villoea (hairy vetch)
Vicia earoliniana (Carolina vetch)
Trifolium pratense (red clover)
Trifolium procumbens (low hop clover)
Trifolium incamatum (crimson clover)
Trifolium repene (white clover) ,
Trifolium dvbium (Least hop clover) ,
Trifolium arvenee (rabbit-foot clover)
Trifolium hybridum (alsike clover)
Medicago arabica (bur-clover)
Medicago eoHva (alfalfa)
Melilotue alba (white sweet clover) ,
Robinia peeudo acacia Gocust tree)
Albizzia julibrieein (silk tree)
Cassia nictitans (sensitive pea)
falcata comosa (hog peanut)
Baptisia Hnctoria (wild indigo)
Cracca virginiana (wild sweet pea)
Cracca spicata (loose flowered goat's rue)
Pisum satitmm (garden pea)
Phaseolus vulgaris (garden bean)
Phaseolus lunatus (lima bean)
Soja max (soy bean)
Meibomia laevigata (smooth tick trefoil)
Meibomia viridiflora (velvet-leaved tick trefoil)
Meibomia obtusa (hairy tick trefoil)
Meibomia panicuiata (panicled tick trefoil)
Vigrui sinensis (cow pea)
Arackis kypogoea (peanut)
Stylosanthes biflora (pencil flower)
Clitoria mariana (butterfly pea)
Pueraria thunbergiana (kudzu vine)
Dolicholus erectus (erect rhynchosia)
Lathyrus odoratus (sweet pea)
Lespedeza striata (Japan clover)
Stizolobium deeringianum (velvet bean) ,
▲GBOr
NUMBBB
ovurxmrn
OF
dajfa
2
3to4
4
3to4
4
2to4
1
3to5
3
1 to6
4
lto4
4
2to3
3
3to5
6
2to6
2
2to6
3
2to5
2
lto5
4
1 to4
2
2 to 4
2
7 to 14
4
lto4
3
5to8
3
2to4
7
6,6
5
5
2
4
2
4to9
2
2to6
2
lto4
6, 6, 10
1
4
1
4
1
4
1
6
1
14
1
6
1
5
1
4
1
5
1
2
1
5
2to4
6
1
5
"1
244 IVAN V. SHUNK
diflferent results obtained by Wilson (1917) who found peritiichic
flagella on the soy bean organism; and Hansen (1919) who found
the single flagella on organisms from the same host, are due to
the age of the cultures at time of staining. From inquiry Conn
learned that Wilson's cultures were sometimes as old as twenty-
eight days, whereas Hansen used two to three day old cultures.
Conn suggests therefore, that the organism may be of the single
flagellate type when two or three days old and becomes peritrichic
when older. However, Wilson's paper (1917) states that the
flagella were stained from one to seven day old cultures so the
peritrichic flagella must have been present in seven days or less,
and he furthermore makes no reference to finding single flagella
in the younger cultures.
While the writer has been unable to stain flagella on the soy
bean organism from very old cultures, yet he has found that up
to ten days old the cultures still show the single flagellate tjrpe,
with no indication that they will ever be anything else.
Wilson demonstrated that his peritrichic organism was able
to form nodules on soy beans, and the strain of the single flagel-
late soy bean organism used by the writer has also been shown to
be able to produce nodules when grown according to the method
of Garman and Didlake (1914). This brings the writer to the
conclusion that in different sections of the coimtry, there is a
different adaptation of nodule bacteria to the soy bean, and that
Wilson and Hansen were working with the two different types.
Although a similar adaptation might be expected in the case
of other I6gume host plants, yet it is interesting to note by
referring to the groups of nodule bacteria f oimd by Burrill and
Hansen (1917) that if one host plant in a group has single flagella,
all other host plants of that group which were investigated gave
single flagella, and similar results were obtained in those groups
having peritrichic flagella.
SUMMARY
1. The flagellation of the organisms from nodules of 41 species
of leguminous plants has been studied.
2. Two distinct types of flagellation have been found, the single
flagellate type and the peritrichic.
FLAGELLATION OF BACTERIA OF LEGUMINOSAE 245
3. As suggested by Hansen (1919) the writer believes that the
nodule bacteria of the Leguminosae are of two groups and if we
follow Migula's classification they belong to two genera, Pseudo-
monas and Bacillus.
4. From 15 genera the flagella were of the single flagellate
type. From 8 genera the flagella were of the peritrichic type.
5. In no case has any difference been found in the type of
flagellation on organisms from plants of different species of a
genus.
6. The single flagellate type is not strictly polar as the flagel-
lum is usually attached at the comer rather than exactly at
the end.
ACKNOWLEDGMENTS
The writer desires to express his thanks and appreciation to
Dr. F. A. Wolf for kindly advice and assistance throughout the
work.
REFERENCES
BuRRiL, T. J., AND Hansen, R. 1917 Is symbiosis possible between legume
bacteria and non-legume plants? 111. Agr. Exp. Sta. Bui. 202, 122-123,
13em37, plates III, IV, V.
Conn, H. J., and Bbsed, R. S. 1920 A suggestion as to the flagellation of the
organisms causing legume nodules. Sci. N. S., 61, 391-302.
Db Rossi, Gino 1907 Ueber die Mikroorganismen, welche die Wurzelkndllchen
der Leguminosen erseugen. Centralb. f. Bakt., 2 Abt., 18, 304.
De Rossi, Gino 1920 Studien tiber den kndllchenerzeugenden Mikroorganis-
mus der Leguminosen. I. Isolierung, bacteriologische Diagnose,
Anwendbarkeit der Kulturen in der land wirtschaft lichen Praxis.
Centralb f. Bakt., 2 Abt., 26, 267.
Fbed, E. B., and Davenpobt, A. 1918 Influence of reaction on nitrogen assim-
ilating bacteria. Jour. Agr. Res., 14, 320-321.
Cabman, H. , and Didlake, M aby 1914 Six different species of nodule bacteria.
Ky. Agr. Exp. Sta. Bui. 184, 343-344.
Hansen, R. 1919 Note on the flagellation of the nodule organisms of the
Leguminosae. Sci. N. S., 60, 568-609.
Harbison, F. C, and Bablow, E. 1907 The nodule organism of the Legumi-
nosae— ^its isolation, cultivation, identification, and commercial appli-
cation. Centralb. f. Bakt., 2 Abt., 19, 427-428, Taf. II, 9, III, 14.
Kellebman, K. F. 1912 The present status of soil inoculation. Centralb.
f. Bakt., 2 Abt., 34, 42-46, Taf. II.
Pbucha, M. J. 1915 Physiological studies of Bacillus radicicola of Canada
field pea. Cornell Agr. Exp. Sta. Mem. 5, 16-18.
Shttnk, I. V. 1920 A modification of Loeffler's flagella stain. Jour. Bact., 6,
181-187.
246 IVAN y. SHUNK
Smith, R. G. 1900 The nodule orgaxu«m of the Leguminoeae. Centralb. f.
Bakt.,2Abt.,6,S71-372.
Wilson, J. K. 1917 Physiological studies of BctciUus radicicola of soy bean
(Soja max. , Piper) and of factors influencing nodule production. Cor-
nell Agr. Exp. Sta. Bui. 386.
ZiPFEL, H. 1912 Beitrage zur Morphologic und Biologic der KnOllchenbakter-
ien der Leguminosen. Centralb. f. Bakt., 2 Abt., SS, 109-110.
PLATE 1
Fig. 1. PhaseoluB vtdgariB (common bean)
Fio. 2. Cracca virffiniana (wild sweet pea)
Fio. 3. Victa viUosa (hairy vetch)
Fig. 4. Vicia caroliniana (Carolina vetch)
Fio. 6. CaxBtia n\eHian» (sensitive pea)
Fio. 6. Trifolium hyhridum (alsike clover)
Fio. 7. Meihomia viridiflora (velvet-leaved Tick Trefoil)
Fig. 8. Trifoltutn dubium (least hop clover)
Fig. 9. AUnMxia julibriaain (silk tree)
Fig. 10. Robinia pseudo acacia (locust tree)
Fig. 11. Stylosanthes Hflora (pencil flower)
Fig. 12. Medicago saliva (alfalfa)
Fig. 13. Vicia saliva (common vetch)
Fig. 14. Pisum salivutn (garden pea)
Fig. 15. Trifolium repens (white clover)
Fig. 16. Melilotus alba (white sweet clover)
Fig. 17. Trifolium arvense (rabbit-foot clover)
Fig. 18. Baptisia tinctoria (wild indigo)
Fig. 19. Vicia alba (vetch)
Fig. 20. Cracca spiccUa (loose flowered Goat's Rue)
Fig. 21. Vicia hirsuia (tineweed or vetch)
Fig. 22. Arachis hypogoea (peanut)
Fig. 23. Medicago arabica (bur-clover)
Fig. 24. Pueraria tkunbergiana (kudzu vine)
Fig. 25. Vida dasycarpa (vetch)
Fig. 26. Falcata comosa (hog peanut)
Fig. 27. Trifolium procumbens (low hop clover)
Fig. 28. Trifolium incamalum (crimson clover)
F{o. 29. Lathyrus odoralus (sweet pea)
Fig. 30. Clitoria mariana (butterfly pea)
Fig. 31. Vicia angustifolia (smaller common vetch)
Fig. 32. Trifolium pralense (red clover)
Fig. 33. Meibomia laevigata (smooth tick trefoil)
Fig. 34. Meibomia panicvlaia (panicled tick trefoil)
Fig. 35. Dolicholus erecius (erect rhynchosia)
Fig. 36. Phascolus lunaius (lima bean)
Fig. 37. Soja max (soy bean)
Fig. 38. Meibomia obtusa (hairy tick trefoil)
Fig. 39. Vigna sinensis (cow pea)
Fig. 40. StitoUbium deeringianum (velvet bean)
Fig. 41. Lespedeta striata (Japan clover)
All drawings were made to the same scale and with the aid of a camera lueida.
JOURNAL OF BACTERIOLOGY. VOL. VI
PLATE 1
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(Shunk: Flagellation of Bacteria of LecuminoBae)
JOUBNAL or BACTBRIOLOaT, YOIi. T|, NO. 2
METHOD FOR THE INTRAVENOUS INJECTION OF
GUINEA-PIGS
GEORGE B. ROTH
Hygienic Laboratory ^ United States Public Health Service, Washington, D. C,
Received for publication September 15, 1920
Up to the present time two weU-known methods have been
employed for the intravenous injection of substances into guinea-
pigs, namely the jugular vein and the ear vein methods.
By certain investigators the first method is considered objec-
tionable by reason qf the fact that when the jugular vein is used
it is exceedingly difficult to control the head of the animal without
interfering with the operator's movements when making the
injections. The marginal vein of the ear which is advocated by
Rous^ can be employed only in selected animals and therefore
is not especially adapted for routine use.
A method for routine work, which seems to have a distinct
advantage over the preceding methods has been elaborated
recently. This makes use of the comparatively large superficial
vein lying on the dorsal and inner aspect of the hind leg of the
animal. This vein nearly always runs diagonally^ across the
leg from the dorsal aspect below to the inner aspect above.
To use the above vessel for intravenous administration an
operating board (fig. 1) has been devised which permits the
operator to manipulate the hind legs of the animal freely and at
the same time does not prevent the legs from being securely
tied. The board proper is made from a flat piece of wood and
is 16 inches long, 8 inches wide and f inch in thickness. It is
similar to an ordinary animal board except that the end to which
^Rous, Peyton. Method for Intravenous Injection of Guinea-Pigs. Jour.
Exper. Med., 1918, 27, 459.
'Occasionally, the vessel may run anteriorly.
249
250 GEORGE B. ROTH
the hind legs are tied has a U-shaped piece cut from it, as shown
in the illustratioD. The board is mounted near its center on an
extension shaft, which is fitted with two joints, the one at the
end to which the board is attached being a ball and socket joint
and the other an adjustable swivel joint. The shaft is screwed
into a metal base which has sufficient weight to hold the board
steadily when placed in any position.
The procedure for making the injection is as follows: With the
board proper placed in a horizontal position, the animal is tied
to it securely, abdomen downward, by means of strings. While
the animal is being anesthetized the board is placed in a vertical
position and rotated on its vertical axis slightly so as to bring
INTRAVENOUS INJECTION OF GUINEA-PIGS
251
the dorsal aspect of the right hind leg into view (fig. 2). After
clipping the hair from the leg and shaving it, the leg is lifted up
slightly by the first, or first and second fingers and lightly com-
pressed by the thumb of the left hand. A small incision, usually
about \ inch long is made diagonally across the leg from the
Fig. 2
outer, lower to the upper and inner aspect (fig. 3). The sub-
cutaneous tissue is then pushed aside with a fine pointed forceps
thereby permitting the vessel to come into view. The vessel
when dilated by suitable compression permits the ready entrance
of a number 23 B. & S. gauge needle, although a number 26
B. & S., f inch needle is usually employed. The needle is always
introduced well into the lumen of the vein so that if there is any
escape of fluid backward it can be prevented by pressure on the
vessel between the point of the needle and the opening in the
vessel. Bleeding from the cut vessel can be readily controlled
by pinching it with small forceps.
ROSE BENGAL AS A GENERAL BACTERIAL STAIN
H. J. CONN
New York Agricultural Experiment Station
Received for publication October 2, 1920
Recently the use of rose bengal was mentioned (Conn, 1918)
as a stain for detecting microorganisms in the soil. It has
subsequently been found to be especially useful in staining two
soil organisms, B. radicicola and Ps. caudatus, both of which are
hard to stain by ordinary methods on account of the slime they
produce. Its use with these two species proved so successful
that it is now one of the bacterial stains most commonly used in
this laboratory, and it almost always gives satisfaction.
Rose bengal is a stain little known among bacteriologists, but
deserves wider use. It belongs to the phthalein series of dyes,
being closely related chemically to eosin. It differs from the
latter stain in that the four atoms of bromine in eosine are
replaced by four atoms of iodine with the addition of two atoms
of chlorine. The dye as formerly made in Germany was appar-
ently quite reliable, but it has scarcely ever been manufactured
in America and it has proved difficult to get a satisfactory product
of domestic manufacture. Some of the imported material is
still available, and after investigation an American-made product
has been found, sold by the Will Corporation as -their "bioloid"
grade, which gives as good results as that of German manufacture.
The formula which has proved satisfactory is: Rose bengal, 1
gram; 5 per cent phenol, 100 cc. This solution remains in good
condition for several months.
The chief value of this stain to the bacteriologist is that it
has a great affinity for bacterial protoplasm but not for the
slime or debris with which the cells are surrounded. It is there-
fore especially to be recommended for slime-formers. B. radici-
cola, for instance, does not take the ordinary bacterial stains
253
254 H. J. CONN
unless it has been carefully separated from its slime, the organisms
remaining unstained in a completely stained field. With rose
bengal, on the other hand, the organisms stain deeply, showing
their characteristic granules, and the field is practically unstained
even though the organisms have been growing on a medium
specially adapted to the production of slime. Ps. caudatus,
which is only about 0.2 micron in diameter (see Conn and Bright,
1919), shows a peculiar and typical granulation with this stain
that had not been suspected after considerable study with other
dyes. Rose bengal, indeed, seems to be unusually well adapted
for revealing structure in small bacterial cells. The very satis-
factory results obtained with it in this laboratory make it seem
worth recommending to bacteriologists in general. Although
more expensive than the more commonly used dyes, its price
is not prohibitive unless an unusual amount of staining is to
be done.
REFERENCES
Conn, H. J. 1918 The microscopic study of bacteria and fungi in soil. N. Y.
Agr. Exp. Sta., Tech. Bui. 64.
Conn, H. J., and Bright, J. W. 1919 Ammonification of manure in soil. J.
Agr. Res., 16, 313-350. Also in N. Y. Agr. Exp. Sta., Tech. Bui. 67.
William Thompboit Sedqwick
WILLIAM THOMPSON SEDGWICK
1855-1921
William Thompson Sedgwick, the father of the modem pub-
lic health movement in America, was bom at West Hartford,
Connecticut, December 29, 1855. He graduated from the
Sheffield Scientific School of Yale University in 1877, his first
contribution to scientific literature being a study of the local
flora, in collaboration with his college chimi and life-long friend,
E, B. Wilson. He began the study of medicine, but, dissat-
isfied with the haphazard medical education of the time, discon-
tinued his course a short time before he would have received
his degree. He taught physiological chemistry imder Chittenden
at the Sheffield Scientific School in 1878-1879, and in 1879
accepted a fellowship in biology at Johns Hopkins where he came
under the influence of Martin, to receive from him the vision of
biology as a broad and liberal science, a vision which Martin
brought over from the England of Huxley and transmitted through
Sedgwick and Sedgwick's pupils to thousands of students in
this coimtry.
Sedgwick was made assistant in biology at Baltimore and
received the degree of Ph.D. in 1881. In the winter following
the reception of his doctorate and on the anniversary of his
birth, December 29, 1881, he was married to Mary Catherine
Rice of New Haven, the beginning of thirty-nine years of a
relationship as complete and as beautiful as ever existed between
man and wife. Mrs. Sedgwick not only gave to her husband a
rare personal devotion which made his health and his comfort
and the success of his career a constantly controlling motive,
but her artistic tastes and rich temperament kept a warmth and
color in his life which made it impossible for Sedgwick ever to
feel those limitations which sometimes accompany a life of
intellectual concentration, limitations which Charles Darwin, for
example, felt so pathetically in his later ye^rSt
255
tOVWKAL or BA0nBlUO|.0OT* TOI.. TT, 9IO. 3
256 C.-B. A. WINSLOW
Sedgwick found his career in 1879, his wife in 1881, and the
institution to which he and his wife devoted their lives with a
rare ardor in 1883. Francis Walker, who was at this time
beginning his brilliant service as president of the Massachusetts
Institute of Technology, had known Sedgwick as a student at
Yale, and with a characteristically broad view of technolo^cal
education, called him to the Institute in 1883 as Assistant Pro-
fessor of Biology. He became Associate Professor in 1884, and
Professor in 1891 and was head of the department (later known
as the Department of Biology and PubUc Health) until his death.
In the present prosperous state of scientific education, it is
a little difficult to realize what the Institute of Technology meant
to its protagonists. In those early days of doubt and difficulty
the Institute became a symbol, an Ark of scientific education to
Walker and the Uttle band who fought for it at his side. Sedg-
wick was one of Walker's closest friends and, like Walker and
so many of his faculty, was inspired by a devotion to the ideals
of the Institute which is bestowed upon church and nation
more often than upon an educational institution.
Sedgwick's original bent was toward physiology and his first
important scientific contribution at the Institute was a study of
the dangers of gas poisoning, conducted in collaboration with
William Ripley Nichols. These were the golden days of the
birth of bacteriology, however, and when Nichols died while on
a visit to the European imiversities some tubes of Koch's strange
new gelatia medium were brought back to the Institute with
his personal effects. Sedgwick was quick to realize the possi-
bilities of the new science and from that time on his own investi-
gations and the energies of his department were focused more
and more on bacteriology. The medical applications of the
subject were being developed by Welch at Baltimore and by
Prudden and Biggs and Park in New York, but Sedgwick's
training and natural aptitudes made him the pioneer in the
broader biological aspects of the new subject. When the
Massachusetts State Board of Health was reorganized and the
Lawrence Experiment Station was established in 1888, he was
appointed biologist to the Bowd and with Mills, Drown and
WILLIAM THOMPSON 8BDGWICK 257
Mrs. Richards and their pupils, Hazen, Whipple, Fuller and
Jordan, he laid the foundation of modem sanitary science in its
bacteriological and engineering aspects, as distinct from those
which deal with the problems of the pathology and diagnosis of
disease. His contributions to epidemiology in the study of
water and milk-borne epidemics, conducted at this time, were of
the highest scientific importance. The growth of the whole
public health movement in America was, from 1890, connected
in an intimate fashion with the development of the Department
of Biology and PubMc Health at the Institute and of the School
for Health Officers conducted in cooperation with Harvard
University during recent years. It would be difficult to name
any important health activity, investigative, administrative or
educational, to which Sedgwick's pupils have not contributed in
an important degree. It may be fairly said that he created the
new field of non-medical sanitary science. Public health began
as a branch of medicine but Sedgwick has taugiht America, and,
through his pupils, is now teaching Europe that the two fields
are intersecting but distinct, and that sanitary engineers, bacte-
riologists and ev^i health administrators may be trained for the
highest type of public service without passing througih the
established coiurse which leads to the medical degree. The last
important idea, which he put forward only a few months before
his death, was the suggestion of a bifurcated course, based on
the same two years of pre-clinical work, but leading in the last
two years to the alternative degrees of Doctor of Medicine or
Doctor of Public Health; and this suggestion was the lo^cal
development of his life work.
Aside from a multitude of important technical papers and
addresses, Sedgwick was the author, or joint author, of five
books which admirably express the more important interests of
his professional hfe. '^ General Biology," published with E. B.
Wilson in 1886 crystallized in effective form the viewpoint
derived, through Martin, from Huxley of biology as a brojad and
fundamental discipline dealing with the underlying phenomena
of protoplasmic action; and no single work has perhaps had so
large an influence upon the teaching of the biological sciences
258 c.-s. A. wmsLOW
in the United States. The ''life and Letters of William Barton
Rogers'' (1896), in the preparation of which Sedgwick assisted
President Roger's widow, was a labor of love which expressed all
the loyalty of the Technology faculty and alumni to the great
founder of the Institute. ''Principles of Sanitary Science and
the Public Health" (1902) was Sedgwick's most important lit-
erary production, a book which is still the best existing epitome
of the principles of sanitary science and which many academic
generations have found "as interesting as a novel." "The
Human Mechanism," a textbook for schools and collies,
published with Theodore Hough in 1906, marked Sedgwick's
return to his earlier interest in physiology and i)ersonal hygiene;
and "A Short History of Science," published with H. W. Tyler
in 1917, placed in permanent form the broad historical sense
and the keen love of origins which were always among the
greatest charms of Sedgwick's courses.
Sedgwick's scientific attainments received recognition in the
conferring of the honorary degrees of Sc.D. by Yale in 1909,
and LL.D. by the University of Cincinnati in 1920, as well as
in election to the American Academy of Arts and Sciences and
the American Philosophical Society. He was appointed a member
of the Advisory Board of the United States Hygienic Laboratory
in 1902, and later received a commission as Assistant Surgeon
General in the United States Public Health Service. He was a
member of the International Health Board of the Rockefeller
Foundation. He was a foimder and first president of the
Society of American Bacteriologists and our organization owes
its establishment and its broad charter more perhaps to him
than to any other individual.. He served also as president of the
American Society of Naturalists, the American Public Health
Association, and the New England Water Works Association.
Sedgwick's interests were, however, never narrowly bounded
by his own technical field. Wherever educational or civic
problems were to be solved he was ready to serve. A score of
progressive movements in Massachusetts numbered him among
their leaders. He was president of the board of trustees of
Sharon Sanatoriimi from 1902 and a member of the Public Health
WILLIAM THOMPSON SBDGWICK 259
Counoil of Massachusetts from its inception. He was a trustee
of Simmons College from its foundation in 1899. He was
chairman of the Pauper Institutions' Trustees of the city of
Boston in 1897-1899. He was a leading figure in the fight for
Civil Service Reform, president of the Boston Civil Service
Reform Association in 1900, and of the State Association in
1901. Finally, as curator of the Lowell Institute siace 1897
he became perhaps more widely known to the citizens of Boston
than in any other capacity. He did not confine himself to the
abstract task of securing for Boston contracts with the most
brilliant teachers of American and European thought; he was
almost nightly on hand to act as a personal host and to give the
problems of heating and lighting and ventilation an individual
attention which made Hxmtington Hall famous throughout the
coimtry.
In all these works of public service Sedgwick was imwearied,
imtil the very day and hour of his death (January 25, 1921).
On Saturday he gave a dinner to some thirty of his colleagues
and pupils in honor of a former student who was going abroad
on a public health mission, and never was he more at his best
in wisdom and courage and enthusiasm. On Monday he was
at his office as usual; the writer will always cherish as one of his
most precious possessions a long letter written on this day,
about a projected journey, full of the soimd counsel and the
detailed practical advice which *'The Chief" always foimd time
to give to his old students. On Tuesday evening he attended a
meeting in the interest of a plan for the formation of a state
university, walked home enjoying the keen, frosty air of the
Boston winter and on his arrival, after a word of cheer to Mrs.
Sedgwick, succumbed in a moment to an attack of an affection
of the heart which had for years threatened but never shadowed
his life. He died without regaining consciousness, a ''Happy
Warrior" in the fight against ignorance and suffering and disease.
Sedgwick was a pioneer in American science and a zealous
public servant; but it was as a teacher that he stood supreme. On
the lecture platform, as in the intimacy of his laboratory, he had
the gift, as rare as it is beneficent, of seiziag the imagination,
260 C,-B. A. WINSLOW
kindlmg the enthusiasm, uxspirmg the will. He was no orator,
but he compelled by the force of a ripe intellect, a genial philos-
ophy and an unswerving ideal. He had the instinct for the vital
point; and in the midst of all his busy life he never failed to gauge
the strength and the weakness of each individual student. He
was pitiless to the specious and the slipshod, and if his, students
did not learn to think honestly and clearly they had only them-
selves to blame.
Sedgwick's most notable intellectual quality was breadth of
vision. He saw every fact in. relation to a hundred other phenom-
ena and he was at his very best with a small group of students,
following out in the experimental vein a line of thought which
might lead from the structure of plant tissue to the domestic
life of ancient Rome, and then to some fundamental problem
in philosophy or ethics. The Bible, the Greek classics and the
poets and essayists of England were always fresh in his mind to
furnish an allusion. He and Mrs. Sedgwick had travelled in
Europe, widely and in unusual by-paths; and he travelled with
eyes so wide open and interest so keen that he saw more and
enjoyed more in a month than many a self-centered tourist can
compass in a year. (One of the things his friends love best to
remember is the satisfaction he derived from his trip to Europe
last summer as exchange professor at Leeds and Cambridge.)
The whole world, past and present, was in the background of
his thoughts. He would take a simple fact and turn it this
way and that, and play with it, and toss it in the air, so that it
caught the light from a hundred different sources. No one who
has ever heard him discuss with a class by the Socratic method
the question, "What is truth, and why do we value it so highly?"
can ever forget that lesson in clear and straightforward and
constructive reasoning. The Institute is a busy place and no
man on its faculty was more active than Sedgwick in multi-
farious lines of public service, yet he was always cahn, serene
and unhmried. If it could ever be said of any man, it was true
of him that he saw life steadily and saw it whole.
Sedgwick had knowledge and wisdom, but, when all is said
and done, it is moral qualities which mark the great teacher.
WILLIAM THOMPSON SEDGWICK 261
''Faith, Hope and Charity" are the things that count in the
long run; and these virtues were his in bountiful degree.
He had an abiding faith in the general scheme of things, a
faith based firmly on the biologists' knowledge of the great
underljring forces which have brought us up from the slime of
the rockpools and which will yet carry us to heights undreamed
of. He "Accepted the Universe," he trusted ''that power not
ourselves that makes for righteousness." His courage was
absolute and instinctive. When he saw the truth he followed
it. In times of doubt and and hesitation, one turned to him as
to a well of clear water in the wilderness.
His optimism was no less notable a characteristic. He be-
lieved in his students and gave them responsibilities that seemed
far beyond their powers, but almost always they "made good."
Scores of young men who bore every sign of mediocrity were
re-made and launched on successful careers by the sheer power
of his confidence. In his public life Sedgwick saw much of the
seamy side of American politics, yet he would approach a case-
hardened politician with the assumption that they shared the
same high ideals of social responsibility, and here too his opti-
mism often bore surprising fruit.
Finally, Sedgwick loved not only mankind but he loved his
fellowmen, which is a rarer and more precious gift. He estab-
lished human relations with extraordinary facility. He knew
his choreman and his elevator boy and the janitors at the Insti-
tute as human beings. One of the most characteristic things
he ever did was the giving of a dinner, when his summer home
at Seal Harbor was completed, to all the carpenters and masons,
his friends and fellow townsmen of the Maine village who had
labored honestly to build it. Above all, it was to his students
that he gave of this power of warm personal sympathy and
comprehension. One thinks always of "Rugby Chapel" as the
ultimate tribute to a great teacher. About Sedgwick, however,
there was something so much closer and more intimate that the
quotation dies on one's lips. The master of Rugby was far off
on the snowy heights. Sedgwick was in the midst of the rush
of life and he held us by the hand, Arnold thought of his father
262 c,-B. A. wmsLOW
as a teacher. We who were Sedgwick's "boys" will think of
our Chief as of a second father.
Yet he led us to the heights no less surely, if he led us always
in warm and human fashion. It was not necessary for him, like
the eastern sages, to go into the wilderness to learn the secret
of selflessness. He knew it always. After a long and intimate
talk with a student, he ended with the words "I think you can
be a very useful man.'' Not a rich man, not a successful man,
not an influential man; a useful man. That was his secret. I
believe that never in his life, in matters great or small, did he
say to himself, " Is it pleasant to do this? " "Is it to my interest
to do this?" but only "WUl this be useful?"
So, in this time, when the world seems very barren without
his personal presence, his pupils and his colleagues and his friends
can have but one thought — to labor more diligently and untir-
ingly, that Sedgwick's spirit of service through knowledge may
still bear fruit throughout the coming years.
C.-E. A. WmsLOW.
THE MAIN LINES OF THE NATURAL BACTERIAL
SYSTEM
S. ORLA-JENSEN
Den polytekniske LaereatutalU bioteknisk^emiske Labor atorium, Copenhagen
Received for publication September 3, 1920
I am happy to see how very mteUigently and thoroughly my
proposition for a natural bacterial system has been discussed by
the Committee appointed by the Society of American Bac-
teriologists (1917). This warrants the hope that some day, when
the single groups of bacteria have been sufficiently studied, the
bacteriologists of the different coimtries may fortxmately come
to an agreement about a fully satisfactory bacterial classifica-
tion. On the other hand, the Committee does not let me hope
that we might agree also upon a more practical system of nomen-
clature than that employed at present in bacteriology, and I
therefore feel impelled to object against the rather severe criti-
cism that the Committee has passed on my efforts in this direction.
The basis of every science is, next to exact investigations, to
throw the greatest possible clearness in the terms to be used.
But science does not consist in pedantically following old-estab-
lished rules. On the contrary, hardly any important progress is
ever accomplished without disregarding some of them. Let us
therefore, as we are now building up a new science, try to avoid
the monstrous mistake committed by zoologists and botanists in
coming rather unmeaning terms which are apt to cause the
greatest difficulties for the memory. Out of regard for posterity,
who probably will find themselves confronted by thousands of
bacterial species, we have to provide for a certain mtrinsic logic
in the nomenclature. No human being would now-a-days be
able to recollect chemistry, were it not that in due time there
had been prepared such an excellent nomenclature that the
263
JOUmKAL or BACTBBXOLOOT, VOL. YZ, HO. 8
264 S. ORLA-JENSEN
name of a chemical compound can be derived directly from the
formula. Even if the principles of chemical nomenclature
cannot be applied to bacteriology, there is no reason here to
form the names servilely upon the principles of linnseus, and it
is so much the more meaningless to do so as the Committee has
already in its classification of bacteria discarded these principles
on the most important point, in giving the biological qualities
precedence over the morphological.
In bacteriology as soon as the purely morphological principle
of classification is abandoned, the relatively few purely mor-
phological generic names do not suffice, but we must necessarily
form a whole series of new generic names. Precisely in ttus
connection I think I have displayed a great deal of conservatism
by simply adding to the old designations a prefix which char-
acterizes the genus more closely. From the generic name we
then are still able to conclude as to the appearance of the bac-
teria in question. In my later work on the lactic acid bacteria
I have given nearly related cocci and rod-forms the same prefix
(for instance, Streptococcus and Streptohacterium, Betacoccua and
Betabacterium) , which I think is also a practical arrangement.
The prefix of the generic name ought no more than the specific
name to allude to a person, not even to the person who first
described the bacteria concerned; for this question is only of
interest in the history of our science, but absolutely not from a
natural-history point of view, and we ought not to encum-
ber the bacteriologists of the future, who will have to handle
thousands of bacterial species, with the history of each. The
name of an organism ought to seem so natural to any one who is
thoroughly acquainted with the organism and knows where it is
to be found, that it will be nothing new to be remembered, but
wiD serve on the contrary to associate his conception of the
particular organism.
As to the family names of the bacteria, it will be convenient
to let all of them end in -Bacteriaceae, by which it will be seen
directly what is in question. If there are to be formed families
of the cocci and spirilla, they must consequently be termed
Coccobacteriaceae and SpinUohacteriojceae (or by the older name
NATURAL BACTERIAL SYSTEM ' 265
of Zopf, Spirohaderiaceae). The reason why I have made an
exception from this rule with the family Actinomycetea is because
by the suffix -mycetes I wish to indicate that we have here the
transition to the Eumycetes; but, in deference to the proposal of
the Committee; I am willing to change the name to Mycobac-
teriaceae. On the other hand, I cannot agree with the Committee
in following the old rule, that ''a family name must be formed
from one of its component genera with the suffix aceoe;" for, if
so, there would most frequently be no sense in the family name
except in regard to this single genus. There cannot be any
doubt but that we ought to form the family name in such a way
that it denotes a property — ^and preferably the most character-
istic one — common to all the bacteria which belong to the family
in question. Accordingly, it is no improvement on the name,
when for the family of oxidizing bacteria set up by me, the
Oxydohacteriaceae, the Committee proposes the name Nitro-
bacteriaceae, which is quite misleading in respect to its first four
genera.
The main objection of the Committee to my system is, that I
do not pay due regard to priority. But what does that really
mean? In old sciences such as zoology and botany we meet with
really time-honored names, the legitimacy of which is quite
indii^utable; but in a new science like bacteriology we cannot
consider the older names as anything more than provisional
labels. Indeed, we have not advanced farther than to find a
number of species, wherever we make a thorough-going study
of a so-called bacterial species, and in by far the largest number
of cases it is quite impossible to guess which of the new species
is meant by the original author.
The Committee itself holds that we ougiht not to take into
consideration the names dating from the time when micro-
organisms were not yet studied in pure culture — or rather the
names proposed prior to 1885, when the system of Zopf appeared,
the system which has formed the basis of the morphological
classifications hitherto used. The Committee does not wish,
however, to build up once more an exclusively morpholo^cal
S3rstem, but a system based essentially on the far more important
266 S. ORLA-JENSEN
biolo^cal properties, and as the researches initiated to that end
are only in an embryonic state, it does not seem necessary to
me that the bacteriologists out of regard for priority should relin-
quish all hope of establishing a practical nomenclature.
Although it is well-known that the red as well as the colorless
sulphur bacteria may appear in all the forms known in the world
of bacteria, and that even a single species of bacteria (for instance,
Crenothrix and Azotobacter) in the first state of development may
only divide in one plane but later in more planes, yet the Com-
mittee cannot admit that in case of other bacteria there may be a
near relationship between sphere-, rod- and screw-forms. Still
I entertain a perhaps not unwarranted hope, that my recently
published monograph of the lactic acid bacteria may be able to
change the opinion of the Committee. Here we have to do with
a large group of bacteria consisting of sphere- as well as rod-
forms, nevertheless forming a natural family which we could call
LtuAohacteriaceae. This family I have founded, of course, not
only on the specially developed power of forming lactic acid
(since there exist many different organisms which are able to
form, at any rate, small quantities of lactic acid) ; but I base it
upon the fact that the bacteria which we call true lactic acid
bacteria have so many other properties in common that there
cannot be any doubt about their close relationship. Thus, they
are Gram-positive, faculatively anaerobic (without surface
growth in stab culture), they make excessively great demands
as to nitrogenous nutriment, and, most remarkably, in con-
tradistinction to most other bacteria, they are unable to liberate
oxygen from peroxide of hydrogen.
The sphere-forms belonging to the lactic acid bacteria ordi-
narily divide only in one plane, and, according as they form
dextro^ or laevo-lactic acid, they belong to the genera Strepto-
coccus or Betacoccus. The acid-forming micrococci and sarcinse,
on the contrary, differ in so many respects from the true lactic
acid bacteria, that they can hardly be placed here. Thus, my
researches lead to the result that it is not the shape that makes
the difference between sphere- and rod-formed bacteria, but, if
anything, the division in one or more planes. The rod-forms
NATUKAL BACTEBIAL SYSTEM 267
(the genera Therrnobacteriumy Streptobacterium and Betabac-
terium) belonging to the lactic acid bacteria are by no means
always straight. They can be screw-formed and (especially Bac-
terium Infidum) bifurcated. Among the propionic acid bacteria,
which also form a natural family, we once more meet with both
sphere and rod forms, and among the latter very often club-
shaped and forked forms.
I am glad to see that Breed, Conn and Baker (1918) in their
critique of the report of the Committee agree with me in the
view that *'the shape of cell or form of body is not a funda-
mental character.'' It is so much the more strange that these
investigators nevertheless finish by setting up a purely morpho-
lo^cal s}rstem.
There is one further particular in which I must dissent from the
Committee, and that is in setting up new genera of pathogenic
bacteria (some of these being moreover named after persons),
and in this particular too Breed, Conn and Baker agree with me.
The pathogenic characters are not always so constant that they
can be used as specific characters; they are often difficult to
maintam when the bacteria are cultivated on artificial media.
Non-pathogenic species can become pathogenic (for instance,
certain streptococci and micrococci) through animal passages or
through mixed infections, or (in the case of certain coU bacteria)
simply by living in the intestinal canal. What is true of the
parasites of animals, will certainly also apply to those of plants,
and we thus know of moulds sometimes appearing as sapro-
phytes, sometimes as parasites. Many so-called pathogenic
species of bacteria ougiht more correctly to be considered as
saprophytes from which more or less virulent varieties are readily
developed, and although such species* are more often met with
in one genus than in another, we must be very cautious in setting
up pathogenic genera. The interest which has been awakened
in the pathogenic bacteria described in medical literature has
hitherto left its trace in bacteriology to such an extent that it has
been attempted to group all known bacteria around these. This
is a step which must necessarily lead to the establishment of
systems as artificial as if in the animal and vegetable kingdoms
268 S. OBLA-JENSEN
we knew only the few parasitic species and tried to group all
other animalB and plants with them. The pathogenic bacteria
are, fortimately, in the minority; the bulk of bacteria are leading
a saprophytic existence and like the plants have their natural
habitats in the soil. We therefore first have to put in order the
saprophjrtes; then we can begin to mediate about where we have
to place the parasites.
From the point of view here maintained I cannot follow Wins-
low in distributing the cocci firstly under the two groups para^
sites and saprophytes, and it seems to me that he is going rather
too far when he uses the chromogenic property of the cocci to
divide them into several genera. The formation of coloring
matter can on an extreme estimate, and only when taken tc^^ther
with other characters, be adopted as a specific character; it
is too variable to be used as a generic character. We must at
times submit to being in doubt about what we are to call a
species and what we are to regard as a variety; but the generic
characters should be in some measure fixed, even thougjh we
m\ist admit that the many transitional forms between the genera
make it impossible to draw quite well-<lefined lines.
On the other hand, I have confirmed the correctness of the
observation of Winslow that acid-forming cocci are always
Gram-positive, whilst the non-acid-forming are, as a rule, Gram-
negative, and consequently it is doubtless right on that ba&ds to
set up two groups of cocci, which — I suppose — ^belong in quite
different places in the bacterial system. However, my two
groups of cocci do not cover those of Winslow, as I believe I
am warranted in separating the lactic add-f orming streptococci,
and grouping them together with the rod-formed lactic acid
bacteria. The acid-forming micrococci and sarcinse I have
brougjht together in the genus Tetracoccm, as I believe it to be
quite as wrong to draw a limit between the micrococci and the
sarcinffi as between the short- and long-chained streptococci
The property of cohering after division, thougih in a certain
measure characteristic of the bacteria, is to a great extent influ-
enced by the temi)erature and the composition of the nutritive
matter. For the Gram-negative, non-acid-forming or, at most,
NATURAL BACTERIAL SYSTEM 269
very slightly acid-forming cocci (among which must probably be
reckoned the gonococci and the meningococci too, as well as
Gram-negative streptococci, if such exist) we might simply use
the generic name CoccuSy or, if they should turn out to have
terminal flageUa, Coccamanas.
Even as unjustifiable as it would be to imite all the q>herical
bacteria into a great family, Coccaceae, would it be to set up the
family SpiriJlaceae. The rule is indubitably that in every bac-
terial family we may meet with both sphere, rod and screw
forms. Certainly the lophotrichic spirilla, both in regard to
their morpholo^cal and to their biological properties, form a
natiuttl group. This thoroughly justifies the setting up of a
genus, SpvriUumy or better SpiramoruUf a new designation,
which would also make it possible to incorporate nearly related
monotrichic species in this group. We should surely be war-
ranted in doing so, since in other genera of cephalotrichic rods
we meet with both monotrichic and lophotrichic species. The
genus VibriOj which the bacteriologists, one and all, reckon
among the family SpiriUaceaey can on the contrary scarcely be
maintained, since these organisms pass gradually through the
phosphorescent bacteria into the cephalotrichic rods.
The only morphological property of the bacteria which can
perhaps be taken into account as a family character, is spore
formation. Yet this property as such is not used in the case of
the sarcinse nor of the spirilla, and it is not always quite constant,
even in the true bacilli. In cheese I have frequently met with
aerobic, gelatin-liquefying, gas-producing plectridia which com-
I)aratively easily lost the ability to form spores and thus were
not distinguishable from the Proteus bacteria. Thus, these
interesting forms not only form the transition between the spore-
forming and the non-spore-forming rods, but, as aerobic plec-
trida, between aerobic and anaerobic bacilli. In my opinion,
we generally know too little as yet about the bacteria to be
warranted in definitely setting up families, and I therefore con-
sider we may safely put that off to the time when all the groups
of bacteria have been as thoroughly studied as the lactic acid
bacteria have recently been.
270 8. ORLA-JENSEN
Buchanan (1917) sets up six orders of bacteria. I shall not
undertake to discuss whether he is right or not, but only i)oint
out that if we follow him consistently the order Evbacteriales
is necessarily to be divided into two orders, which we may call
Psevdam^madales and Peritrichinales, as these two groups are
by no means more closely related than Pseudorrumadales and
Thiohacteriales (the sulphur bacteria), forming together the
cephalotrichic bacteria. Again to reduce the seven orders
thus established to the corresponding families would perhaps
not be a quite imsatisfactory solution of the family problem.
If we class together the genera which I have set up — ^with the
amendments occasioned by my experience and that acquired by
other researchers — ^into the above-mentioned two orders, we
arrive at the following general synopsis:
Order 1: Pseudomonadalea Order B: Peritrichinalea
1 Methanomonas 1 Thermobacterium
2 Carboxydomonas 2 Streptobacterium
3 Hydrogenomonas 3 Streptococcus
4 NitroBomonas 4 Betabacterium
5 Nitromonas 5 Betacoccus
6 Azotomonas 6 Propionibacterium*
7 Rhizomonas 7 Microbacterium*
8 Acetimonas 8 Tetracoccus
9 Fluormonas 9 Coccus
10 Photomonas 10 Bacterium*
11 Spiromonas 11 Bacillus*
12 Clostridium*
As for the position of Rhizomonas (Rhizobium) in the system,
I accept the proposal of the Committee, to place it next to
Azotomonas (Azotobacter) . I have myself really met with forked
cells in different genera of bacteria and thus cannot attach a
decisive, systematic importance to the furcation. After the
researches of Barthel (1917) and those of Burrill and Hansen
(1917) it must now be considered as certain that Rhizomonas
is lophotrichic, and as a Gram-negative, lophotrichic nitrogen
gatherer it ranks naturally with Azotomonas.
On the other hand, I cannot accept the proposition of the
Committee to give the acetic acid bacteria the generic name
NATURAL BACTERIAL SYSTEM 271
Mycoderma, since — ^apart from the circumstance that this name
does not fit in with my nomenclatm'e — ^it is already generally
used as a generic name of certain pellicle-forming yeasts. More-
over, the designation Mycoderma (Mycoderma vini and Myco^
derma aceti) dates from a far more ancient time than that cited
by the Committee.
Although. the property of setting free nitrogen from nitrates
and nitrites is not of so general occurrence among the bacteria
as is the property of reducing nitrate to nitrite or ammonia, we
meet with the property of denitrification in different bacterial
genera, and hence it would be unwarrantable to maintain the
genera DenUromonas and Denitrohacberium^ set up by me. As
the property of liquefying gelatin also cdnnot be adopted as a
generic character but only as a species character, I think it
would be best to group together my earlier genera DenUromonas
and lAguidomonas in a single genus, which can be conveniently
termed Fhwrmonas, as the bacteria of this group are ordinarily
fluorescent. I cannot agree to call this genus Psevdomonas
merely out of regard for so-called priority, as each and all of the
bacteria which belong to the order under consideration are
really Pseudomonades as well.
As the phosphorescent bacteria form, biolo^cally, a connected
whole, I deem it correct to unite them so as to form one genus,
for which a better name than Photomonas can hardly be found.
According to the experience we have acquired in regard to the
nitrate-reducing bacteria there will scarcely be any reason to
create a special genus for sulphate-reducing bacteria; but we
naturally include the vibrios belonging here in the genus Spiro-
monas. The reason why I prefer this designation over the
generic name Spirillum, has been mentioned above.
As for the second order of bacteria, I provisionally follow the
proposition of the Committee with the differences justified by
my researches on the lactic acid bacteria. I have no doubt that
the genera marked with an asterisk (*), when studied more
closely, will dissolve into two or more genera, some of which will
cover some of those proposed in my natural bacterial system.
272 S. ORLA-JENSEN
Whereas the shape of cells was formerly used as a family
character, I have adopted it only as a generic one, and if we do
not want to fmther confine its signification and only consider it
as a specific character, we shall doubtless have to set up the
genus Propiomcoccus besides the genus Propumtbacterium.
Microhaclerium is to be xmderstood as merely a provisional
collective name for Gram-positive rods of size "a little smaller
than the ordinary bacteria. In biological respects some of these
rods {BaciUvs acidophilus) are closely related to the true lactic
acid bacteria, whereas others approach the Tetracocci or the
aerobic bacilli.
The genus Tetracoccus, including strictly aerobic as well as
strictly anaerobic-species, is probably of as polygenetic a nature
as is the genus Microhacterium, and the genus Coccus perhaps
does not belong at all in the order of bacteria in question. In
biolo^cal respects the Gram-negative, strictly aerobic, chromo-
genic cocci certainly appear to attach themselves rather closely
to the genus Fluormonas; yet their place in the system caimot be
determined with certainty until the arrangement of the flagella
of the motile species has been studied.
The genus Bacterium will undoubtedly dissolve into several
genera, of which I may especially mention the Colibacterium and
Aerogenesbacterium. The reason why I am now inclined, in
contrast to. my earlier opinion, to consider the coli- and aero-
genesbacteria as two different genera, is because they differ
not only in morphological, but, as later researches have shown,
also in biological respects. I have myself proved (1914), that
the Aerogenesbacteria completely oxidize the carbohydrates
when the nutrient matter offers a sufficient buffer effect, and
they thus correspond with their name in forming more gas than
do other bacteria, and Rogers, Clark and Davis (1914) have
shown that in the gas developed by the Colibacteria there is
proportionately more hydrogen than in that developed by the
Aerogenesbacteria. Perhaps the Conmiittee is right in not
regarding the Proteus-bacteria (my genus Liquidomonas) as a
separate genus, as their whole metabolism indicates that they
are to be looked upon as gelatin-liquefying Coli- and Aero-
genesbacteria.
NATUBAL BACTERIAL SYSTEM 273
Just as the behavior towards the different sugars is one of
the most valuable characteristics of the acid-forming bacteria,
so the relation to the different amino-acids can be used to divide
the ammonia-forming bacteria, and this probably is the way to
arrive at a closer division of the genus BaciUus.
The use of the term Clostridium as a generic name presents the
inconvenience that under the same we must group together not
only the Clostridia but also the plectridia. The division into
true butyric acid bacteria (BxUyrichatridium) , the requirements
of which in regard to nitrogenous nutriment are very moderate
(they are able to assimilate even the nitrogen of the air) and
anaerobic, putrefying bacteria (PiUridostridium) seems natural
to me.
As all Pseudomonades — so far as I know — ^are completely or
partially decolorized by Gram, it is reasonable to seek a connec-
tion with the peritrichic bacteria among the Gram-negative
representatives of the latter group, and it ranges naturally from
the denitrificating species of the genus Fluormonas to the denitri-
ficating species of the genus Bacterium. The development then
from here has gone farther in one direction to the putrefjdng
bacteria, characterized by breaking down amino-acids, and in
the other direction to the lactic acid bacteria, which are not able
to attack amino-acids, but demand the most complex nitrog-
enous nutriment.
REFERENCES
Barthel, C. 1917 Zeitschrift fOr G&rungsphysiologie, 6, 13-17.
Breed, R. S., Conn, H. J., and Baker, J. C. 1918 Jour. Bact., 8, 445-459.
Buc?HANAN, R. E. 1917 Jour. Bact., 2, 165-1^4, 347-350.
BuRRiLL, T. J. AND Hanben, R. 1917 111. Agr. Exp. Stat. Bull. 202.
Orla-Jensbn, S. 1907 Det kgl. danske Videnskabemes Selskabs Overaigter,
No. 5.
Orla-Jensen, S. 1909 Centralblatt f. Bacteriologie, 2 Abt., 22, 305-346.
Orla-Jensen, S. 1914 International Dairy Congress at Bern.
Rogers, L. A., Clark, W. M., and Davib, B. J. 1914 Jour. Infect. Dis. , 14,411-475.
WiNSLOW, C.-E. A., AND OTHERS 1917 Jour. Bact., 2, 505-566.
VARIATIONS IN TYPHOID BACILLI'
KAN-ICHIRO MORISHIMA
Department of Bacteriology , College of Physidana and Surgeons, Columbia
University, New York City
Received for publication September 10, 1920
INTRODUCTION
Just as there is often great difficulty in diagnosing atypical
clinical conditions, so great difficulty may be experienced in
identif3ring bacteria which develop abnormal characteristics.
The acquisition, by individual strains of many species of bacteria,
of morphological and cultural characteristics which differ from
the usual type has been noted by many observers and has been
referred to more or less loosely by several different terms. Thus,
Neisser (1906) and Massini (1907) used the word ^'mutation''
to designate atypical forms of Bad. coli, Pringsheim (1911)
speaks of an ''adaptation'' of bacteria, and Gumey-Dixon (1919)
uses the term "transmutation."
We can sometimes follow such variations by gradual changes,
from one stage to another, during which the bacteria pass through
a process of evolution, adapting themselves to their surroundings.
Such variations may consist in the acquisition of new morpho-
logical, biochemical, or serological characters, in the loss of
similar properties, or the two processes may occur at one and
the same time. The change may be sudden or gradual, and is
generally retained by the offspring.
The study of such variations is of fundamental importance to
an understanding of the bacteria and may have considerable
botanical importance since it would seem that processes of
evolution or adaptation could be most easily investigated with
^ Submitted in partial fulfillment of the requirements for the degree of Doctor
of Philosophy, in the Faculty of Pure Science, Columbia University, May, 1020.
275
276 KAN-ICHIRO MOmSHIMA
fonns whose characteristics are easily studied and in which
generation follows generation with such speed that observation
over the period of a year or longer might correspond to ages
of development among the higher species. Moreover, from a
purely practical point of view it is necessary to know to some
extent just how much and how permanent a degree of variation
is to be expected when well-known species are subjected to alter-
nation between the conditions prevalent in artificial media and
those existing in the human and animal bodies.
In the following studies the writer has occupied himself exclu-
sively with the changes observed in the typhoid bacillus.
Strains
The cultures employed in this study were 138 in number and had been
carried on artificial mediums since their isolation from patients. They
were divided into three groups, as follows :
1. The stock cultures of the United States Army Medical School . . 116
2. Cultures collected by Dr. Oscar Teague 10
3. Cultures collected by Lieut. R. C. Colwell in France, and given
us by courtesy of Lieutenant-Colonel Nichols 12
The sources of these cultures were as follows:
N.
Blood cultures 55
Stool cultures « 15
Urine cultures 11
Bile cultures 1
Sources unknown 56
Duration of cultivation on artificial media:
Over two years 15
One to two years 25
Six to twelve months 42
Less than six months 32
Recent isolation 11
Age unknown 13
VARIATIONS IN TYPHOID BACILLI 277
Media and technique
In our experiments the media used and technique employed were as
follows:
(a) Meat infusion broth. Meat infusion inoculated with Bad. coli^
incubated about twenty-four hours at 37°C., autoclaved and filtered.
To this was added 1 per cent pepton and 0.5 per cent sodium chloride.
(b) Nutrose broth. Instead of meat infusion 0.25 per cent nutrose
was used. Both broth media were autoclaved for fifteen minutes at 15
pounds' pressure, and the reaction was adjusted to pH 7.0 or pH 7.1.
(c) Media containing sugars. In order to diminish the risk of decom-
posing the sugars during sterilization, they were dissolved in sterile
distilled water, and heated in the autoclave for ten minutes at 10
pounds' pressure.
The sterilized sugar solution was added in the proportion of 1 per cent
to the sterile broth together with 5 cc. of sterilized litmus or 5 cc. of
2 per cent phenol red and 1.2 cc. of decolorized 1 per cent aqueous
solution of china blue (Morishima, 1917) per 100 cc. of the broth. Then
the medium was transferred to small test tubes, and allowed to stand
at least twenty-four hours at 37^C. in an incubator and for twenty-four
hours at room temperature before being used.
For plates meat infusion agar (2 per cent) containing 1 per cent of
the sugar was used. Decolorized china blue was then added in the
proportion given above for the fluid medium. The reaction of all media
mentioned above was adjusted to pH » 7.0 or pH = 7.1 by means of
phenol red.
The stock cultures were transferred to agar slopes and incubated over
night. Then pepton water tubes (1 per cent pepton 0.5 per cent salt
solution, reaction pH 7.0) were inoculated from the slant cultures.
After the latter had been incubated over night, one loopful of the pepton
water growth was transferred to each tube of sug^r medium; agglutina^
tion tests with the pepton cultiu^s were also carried out.
In plating cultures on Endo or any other plates, one or two loopfuls
of bacterial suspensions were usuaUy streaked close to the margin of thd
Petri dish. The plate was divided into five parts by lines drawn on its
bottom. From the first streak made with the loop, the suspension
was spread over one-fifth of the surface; from the border of this area
over the next third, and then from the last border over the remaining
surface. By this method the distribution of bacteria was found to be
satisfactory (Morishima, 1917). They were then kept in the incuba-
278 KAN-ICHIBO MORISHIMA
tor until the end of the experiment. Endo plates were occasionally
inoculated from the sugar media in order to control possible contami-
nation of the latter.
I. Variations in the Utilization of Carbohydrates
Variations in the biological behavior of the typhoid bacillus
have been the subject of a great deal of investigation but, in the
earlier work, especially, the identification of the races under
observation was often incomplete (at least as far as one can
judge from the publications) and all the reported results cannot
be accepted without analysis.
Some of the earliest work was done on indol formation and
on the fermentation of lactose.
Miss Peckham (1897) induced indol formation in a nimiber of
strains of Bad. typhosum.
Wilson (1902) isolated a strain from a typhoid carrier which pro-
duced acidity in lactose media at 22^C. while it did not produce it at
37°C. and the strain agglutinated only in 1:50 dilution of a typhoid
serum of high titre. In other respects it resembled typical typhoid
strains.
Klotz (1904) isolated from the St. Lawrence River water, a tjrphoid-
like organism which he called B, periurbans. It fermented lactose and
sucrose, formed indol, produced acidity in milk without coagulation
and agglutinated with 1:2480 dilution of anti-typhoid serum.
McNaught (1905) isolated two organisms which he named B, typho^m
similanSy one of them from harbor water, the other from a well. The
former did not produce indol and the latter did. Neither aggluti-
nated in anti-typhoid serum. Both were motile when isolated but after
some days of cultivation lost their motility.
Elotz's strain isolated from the water of the St. Lawrence River;
McNaught's B, typhosus similans; and Wilson's strain isolated from a
typhoid carrier's stool cannot be definitely accepted as real typhoid
bacilli, because they were not sufficiently investigated to determine
this fact positively.
Mandelbaum (1912) obtained a bacillus from the blood or feces of
more than fifty patients with clinical typhoid fever in Munich, which he
named B. metatyphi. This bacillus resembled Bad. typhosum in all
respects except that it produced alkali instead of acid in media con-
VABIATIONS IN TYPHOID BACILLI 279
taining glycerol. He showed that these cases were infected, in all prob-
ability from the same typhoid carrier, a woman who served as a milker
in a dairy near Munich. This woman harbored both typical and atypi-
cal bacilli. The B. metalyphi retained the property of producing alkali
in glycerol medium for five and one-half years when transplanted on
plain nutrient agar. Russowici (1908) reported one case of B. meta"
typhi, and Ditthom and Luerssen (1912) reported two similar cases.
Jacobsen obtained (1910) a bacillus which he described as B. typhi
mtUdbile from a small epidemic of clinical typhoid fever in an insane
asylum in Denmark. It resembled Bad. typhoBum in all respects
except the following:
1. It fermented mannitol after fifty hoiu^. 2. Its growth was
strongly inhibited on C!onradi-Drigalski agar or plain agar which had
been autoclaved. 3. Cultures from the plates showing retarded growth
did not agglutinate in typhoid inmiune serum, but cultures of the same
strain on media yielding good growth gave typical agglutination with
typhoid immime serum and resembled Bad. typhosum in all other
respects. B, typhi mutabile gave good specific agglutination five
months after its isolation. There was normal growth on the Endo
plates which removed the inhibitory action exerted on this strain by
other media.
Fromme (1911) reports a bacillus, the growth of which was retarded
on nutrient agar but which grew in ascitic fluid, hiunan blood, guinea
pig's blood, rabbit's blood and egg-yolk or on agar to which sodium
sulphite had been added. His bacillus differed from Jacobsen's in that
it agglutinated with typhoid immune serum from the start.
The variants of typhoid bacilli — B. metatyphid (Mandelbaum), B.
typhi miUabile (Jacobsen) and the xylose non-fermenter of Weiss are
unquestionably true Bad. typhoeum.
Twort (1907) after growing a strain of Bad. typhosum for two years
in lactose media succeeded in producing a strain that fermented lactose.
He also conducted special experiments with a typhoid bacillus which
had acquired the power of fennenting dulcitol. When such a culture
was plated out on agar, subcultures from single colonies retained the
dulcitol splitting powers, although they were still capable of being
agglutinated by a typhoid immune serum, thus proving that the fer-
mentation was not due to any contaminating microbe. On inoculat-
ing the dulcitol-fermenting typhoid culture into a guinea pig, subcul-
tures were obtained showing the same reactions and these reactions
were also maintained, even when the organism was grown for several
280 KAN-IGHmO MORISHBCA
generations on ordinary pepton agar. His conclusions were that the
sugar fermenting powers of an organism may be artificially changed
by growing the said organism for a succession of generations in media
containing a sugar which at the commencement of the experiment it
was unable to ferment.
Kuwabara (1907, 1909) under the direction of Dr. Shiga isolated an
atypical typhoid in addition to a typical one from a typhoid patient's
stool. It fermented lactose, sucrose, and milk-whey as Bact. colt does
and produced reddish color on Endo and Conradi-Drigalski plates but
agglutinated in antityphoid rabbit serum in high dilutions just as a
normal culture of typhoid bacilli did. After twelve to fifteen passages
through plain laboratory nutrient media these atypical characters all
disappeared.
The results of Twort and Kuwabara amount practically to a
complete alteration of the identification characteristics of the
typhoid bacillus. These observations are of the greatest theoreti-
cal importance but fortunately strains of this nature have been
produced or observed so rarely that they cannot be regarded
as a practically important factor of confusion in identification.
This is apparent from Penfold's work cited below.
Penfold (1910a, 1910b, 1911, 1914) as cited by Dixon, working with
twenty strains and carrying many of them for more than a year in a
lactose medium, obtained only negative results; he showed that the
Twort lactose fermenting strain gave rise to daughter colonies on lactose
agar. This Twort culture fermented sorbitol in broth only after a
number of days and Penfold found that it also gave rise to daughter
colonies on sorbitol agar. He observed with some of his cultures late
acid production in rhamnose broth and on transplanting from rhanmose
broth to rhamnose broth after several weeks of incubation, he. was able
to obtain subcultures which fermented in one, two or three days. He
also made a very careful study of the behavior of Bad. typhosum in
dulcitol broth and on neutral red dulcitol agar. In one of his experi-
ments in which fourteen strains were inoculated into dulcitol broth the
first signs of acidity occurred in from five to fifteen days. If, after one
month, subcultures were made in new dulcitol broth, an add reaction
was produced in from one to four days. Subcultures, which had been
trained to ferment dulcitol rapidly showed great permanency; one such
culture transplanted twenty-five times in pepton water during a period
VABIATIONS IN TYPHOID BACILLI 281
of five months and then plated on neutral red dulcitol agar yielded only
fermenting colonies. Twenty colonies from a MacConkey plate of pure
typhoid were inoculated into dulcitol broth; the time required for acidity
to appear varied from eleven to thirty-two days. Slow fermenters of
dulcitol died in dulcitol broth in two months while quick fermenters
remained alive longer. He found one strain which did not ferment ara-
binose, but which after three months' subculturings became a quick
fermenter. Three strains that did not ferment glycerol became after
eight months' subcultivation quick fermenters, but never in less time
than three to four days. In plating out on glycerol media he found a
mixture of quick and slow fermenters.
Reiner Mliller (1908, 1911) did not observe acid production in rham-
nose by any of his typhoid cultures and noticed that the colonies on the
rhamnose plates remained small and delicate but that 5 per cent rham-
nose produced no more inhibition than 0.5 per cent. He showed,
further, that other bacteria of the typhoid-colon group are not inhib-
ited by rhamnose. He observed no production of acidity by typhoid
bacilU on litmus agar containing arabinose, dulcitol or raffinose, but he
observed acidity on rhamnose Endo agar.
Bull and Pritchett (1916) foimd an atypical tjrphoid strain
showing irregularity in fermentation, glucose^ levulose, and
dextrin being all positive and the other sugars negative; indol
being positive as in the case of Bact. coli, but the organism
agglutinated in 1 :20,(K)0 dilution.
Krumwiede, Kohn and Valentine (1918) inoculated thirty-
seven strains of Bact. typhosum into xylose broth and foimd that
twenty-nine produced acid in twenty-four hours while eight of
the strains required from five to thirteen days for this result.
Winslow, Kligler, and Rothberg (1919) recently reported the
results of similar investigations of various bacteria. They
describe the typical typhoid bacillus as a Gram-negative, non-
spore-forming rod, actively motile. It forms translucent irregular
colonies on gelatin media and faint, nearly colorless growths on
potato. It produces strong and prompt acid but no gas in media
containing the hexoses, maltose, mannitol, sorbitol, xylose and
dextrin; it does not attack arabinose, rhamnose, or lactose;
produces a slight initial reddening of litmus milk, which after
two weeks reverts to a neutral or slightly alkaline reaction. It
282 KAK-ICHIBO MORISHIMA
fails to form indol or liquefy gelatin, will not grow in asparagin-
mannitol medium, does not reduce neutral red and causes brown-
ing of lead acetate media. It has low tolerance for acid, but
rather high tolerance for brilliant green dyes and alkali. It
has characteristic serum agglutination reactions and is foimd in
human stools and urines as an actual or potential cause of typhoid
fever.
OXJB OWN WORK ON VARIATION IN THE UTILIZATION OF
CARBOHYDRATES
Some of this work has already been reported in the Journal
of Infectious Diseases, 1920, 26, 52-76. The following table
represents a condensed summary of previous work, together with
new experiments performed since then :
Sv/gar fermentation
Arabinose broth
Nuwim-of
First series. Meat infusion broth (litmus indicator) 114
Second series. Nutrose broth (phenol red, china blue, indicators). 117
Third series. The same medium 21
Fourth series. Meat infusion broth (phenol red, china blue, indi-
cators) 24
Results were as follows:
Positive on the second day 2
Positive on the third day 1
Positive on the fourth day 2
Positive on the sixth day 6
Positive on the seventh day .....* 4
Positive on the ninth day 1
Positive on the tenth day 2
Positive on the eleventh day 1
Positive on the fourteenth day 1
Positive on the twenty-third day 1
Positive on the twenty-fourth day 1
Positive on the twenty-eighth day 1
Positive (total) 23
Negative on the 30th day 279
The proportion of positives is 8.24 per cent against 91.76 per cent of negatives.
VABIATIONS IN TTPHOID BACILLI 283
Dvldtol
We could not obtain uniform fermentation results with this
sugar, despite many attempts. Some strains gave rise to acid
at one time and failed to do so at others. On the other hand
certain strains gave rise to alkalinity at the iBrst test and in later
tests gave an acid reaction. Usually they produced acid in
from one to three weeks.
Numbwrof
attaint
First series. Meat infusion broth (litmus) 115
Second series. Meat infusion broth (litmus) 57
Third series. Nutrose broth (phenol red, china blue) 21
Fourth series. Meat infusion broth (phenol red, china blue) 29
Fifth series. Meat infusion broth (phenol red, china blue) 130
The results were as below:
Positive on the fourth day 1
Positive on the sixth day 26
Positive on the seventh day 15
Positive on the ninth day 31
Positive on the tenth day 2
Positive on the eleventh day 7
Positive on the twelfth day 11
Positive on the thirteenth day 0
Positive on the fourteenth day 11
Positive on the fifteenth day 11
Positive on the sixteenth day 3
Positive on the seventeenth day 3
Positive on the nineteenth day 1
Positive on the twenty-third day 12
Positive on the twentynsixth day 3
Positive on the thirtieth day 9
Positive on the thirty-first day 1
Total positive on or before the thirty-first day 186
Negative on thirty-first day 175
The proportion of positives is 51.51 per cent against 48.49 per cent of negatives.
In all of these tests there was a greater tendency for the indi-
cators (litmus^ or china blue-phenol red) to become reduced than
was evident in arabinose or xylose broth cultures. For this
reason it is possible that the percentage of positives may be too
low, as all tubes showing reduction were recorded as negative.
284 KAN-ICHIRO MORISHIMA
Glycerol
Glycerol broth
We prepared 1 per cent glycerol meat infusion broth, using
china blue-phenol red indicator.
First series 123
Second series , 10
Third series « 10
Fourth series 10
Total 153
All of the cultures produced acidity.
Recently we studied these phenomena with 257 freshly isolated
typhoid cultures from typhoid carriers' stools, using two different
percentages of glycerol, namely 2 per cent and 6 per cent. We
never found any alkali production in the early stage of incubation,
but observed acid production between the third and eighth
day; later some of the cultures showed reduction of color.
Inosite
Inosite is not a true sugar, but its character is similar to that
of sugar and therefore it deserves discussion here.
Inosite broth
One hundred and forty-two strains were inoculated in 1 per
cent inosite meat infusion broth, using china blue, phenol red
indicator. No fermentation or gas production resulted after
thirty days' incubation. Nine subcultures were transferred from
inosite broth to inosite broth with the same result.
Raffinose
Raffinose broth
We used 1 per cent raffiAOse meat infusion broth, with china
blue-phenol red indicator. In the first and fourth series, tjrphoid
bacilli did not grow. The media showed slight acidity before
VARIATIONS IN TTPHOID BACILLI 285
inoculation, but not sufficient to account for the inhibition of
growth of typhoid bacilli. We do not know what substance
caused this inhibitory action.
In the second series 60 strains and in the third series 21 strains
were inoculated; all tubes became alkaline on the second day
and showed no fermentation after thirty days' incubation. Of
course both sets of media showed a neutral reaction before
inoculation. Subcultures from a few of these raffinose broth
cultures in raffinose broth again failed to produce fermentation.
Rhatnnose
Rhamnose broth
One per cent rhamnose meat infusion broth, with china blue
and phenol red as indicators was used for this experiment. One
set of tubes was inoculated with 144 strains of typhoid, and
another with 19 strains. Both produced alkalinity after twenty-
four to forty-eight hours' incubation.
Scdicin
Salicin broth
One per cent salicin meat infusion broth, containing china
blue and phenol red indicator, was used. Two series of experi-
ments, with 144 strains and with 21 strains were carried out,
but no fermentation resulted during thirty days' incubation.
Xylose
We used for the most part 1 per cent xylose meat infusion
broth, with china blue and phenol red indicator. During the
course of this study we carried on many fermentation experi-
ments, in which we foimd 8 per cent of 126 strains to be xylose
non-fermenters, while the remaining strains all fermented xylose
in twenty-four hours. Apparently these 10 negative strains,
and in addition 12 strains brought from France by Lieutenant
Colwell were foimd to be slow xylose fermenters. On canying
286 KAN-ICHmO M0RI8HIKA
subcultures of these strains from xylose broth to xylose broth
ten strains (not Lieutenant Colwell's strains) became xylose
fermenters in twenty-four hours (or somewhat later) after a
few transfers.
CROSS FEBMENTATION OF BACTERIA IN DIFFERENT SUGARS
It might be supposed that a single enzyme produced by
bacteria when cultivated in sugar media, especially those closely
related, such as xylose and arabinose, might ferment more than
one sugar. To test this supposition, 6 xylose fermenters, 7
arabinose fermenters, 9 dulcitol fermenters (all fermenting in
twenty-four hours) and 6 xylose slow fermenters, 6 arabinose
slow fermenters and 7 dulcitol fermenters were inoculated into
three sets of sugar media. We could not find any evidence of
cross fermentation. After thirty-five days' incubation the fer-
menter of a given sugar still continued to ferment the same
sugar, and no other. Therefore, the enzymes produced by
bacteria are, as assiuned by many workers, specific for each
sugar.
DURATION OF THE FERBfENTINQ POWER
Some strains, which had been artificially induced to ferment
certain sugars, maintained their fermenting power after three
or four months, or even half a year, although few transplantar
tions were made from one fresh medium to another, this being
done in some cases to media containing no sugar. Other strains,
however, lost their fermenting power quickly, after only one or
two transplantations. Dulcitol fermenters especially are apt
to be changeable. Our records show two strains which at first
fermented dulcitol in twenty-four hours. Later one of them
fermented dulcitol only after four days and the other after
twenty-one days. Similarly a strain which at first fermented
arabinose in twenty-four hours, later required six days for the
fermentation of this sugar.
VARIATIONS IN TYPHOID BACILLI 287
FERMENTATION REACTIONS UNDER ANAEROBIC CONDITIONS
In the preceding experiments our cultures were grown under
aerobic conditions. The following experiments were carried out
anaerobically:
Two methods were used in these experiments. One was a combi-
nation of exhaustion and absorption with pyrogallol as used in this
laboratory for routine work; and the other was the one devised by
Mcintosh and Fildes.
For the latter method we used a glass jar, connected by means of
tubing with a tank of compressed hydrogen, which was inverted m a
larger jar filled with water to a level of two or three inches above the
inverted jar. The latter is held down by weights when its contents are
displaced by hydrogen. Another tube fitted with a clamp connects
this jar with the jar containing cultures. When everything is pre-
pared iQ the culture jar a copper gauze package containing platinum
asbestos is heated to redness and placed in the culture jar. The jar
is sealed and the clamp released gradually thus allowing the hydrogen
to enter the culture jar. The platinum asbestos will act as a catalyser
to cause combination of oxygen and hydrogen.
When the oxygen in the jar is exhausted no more hydrogen will enter
the jar. Then we seal the glass tubing to prevent the entry of air.
On accoimt of its greater convenience we used the latter method
more frequently.
Typhoid bacilli did not grow well under anaerobic conditions;
consequently all reactions in sugar media were somewhat slower
than imder aerobic conditions.
A. Sugar broth cultures
We tried six strains in 0.01 per cent glucose, 1 per cent raflBnose,
1 per cent arabinose, 1 per cent dulcitol, 1 and 2 per cent rham-
nose, 1 per cent xylose and 2 per cent xylose. The results were
as follows :
(a) Glucose
Aerobic: On twenty-four hours' incubation media distinctly
showed alkalinity.
Anaerobic: Very slightly alkaline, even after ten days' incuba-
tion.
288 KAN-ICHIRO MOBISHIMA
(b) Dulciiol
Aerobic: On tenth day, two cultures showed good acidity and on
twentieth day four of them showed good acidity.
Anaerobic: Did not show acidity on tenth day; on twentieth day
three of them showed slight acidity.
(c) Rhamnose
Aerobic : On the f omth day showed good alkalinity.
Anaerobic : On fifteenth day began to show alkalinity.
(d) Xylose.
True xylose fermenters ferment in twenty-four hourSi under
both conditions. The results with four slow fermenters follow:
Aerobic: On sixth day one of them and on the eighth day two
strains began to ferment.
Anaerobic: Up to the twentieth day no change in reaction
appeared, then the same strains that fermented xylose under
aerobic conditions produced very slight acidity.
(e) Arabinose
Aerobic: On the third day, they showed alkalinity and on the
fifth day one strain showed slight acidity.
Anaerobic: Slight alkalinity persisted until the twenty-first day.
(f) Raffinose
Aerobic: On second day showed alkalinity.
Anaerobic: On the eighteenth day showed slight alkalinity. In
second series, we tested four strains, and in a third series,
four strains on xylose broth but they did not show sufiiciently
definite changes to be described here.
It will be seen from the above that our own work does not
in every way agree with the work of others cited at the begin-
ning of this section. As stated above, we believe that the strains
of Klotz, McNaught and Wilson cannot be definitely accepted
as having been true typhoid bacilli.
In regard to Mandelbaum's Bacillus metatypki we feel that
our results seem to indicate that Mandelbaum was dealing with
slow glycerol fermenters rather than with known fermenting
strains. We should add, however, that we ourselves never
encoimtered any strains which exhibited the characteristics
described by Mandelbaum.
As for the strains of Jacobsen none of our cultures corresponded
to these.
VARIATIONS IN TYPHOID BACILLI 289
As to the results of Penf old and Reiner-MuUer^ our results
agree pretty definitely with those reported by these workers.
No strains corresponding to those described by Bull and
Pritchett were met with by us and we were able to find no similar
ones described in the literature.
We have confirmed the observations of Krumwiede^ Kohn
and Valentine^ and in addition have shown in this work, as well
as in a previous publication with Dr. Teague, that rapid xylose
f ermenters can be produced from slow f ermenters with consider-
able ease.
Although in aknost every respect our work corresponds with
that of Winslow^ Eligler and Rothberg, they do not entirely
correspond with the results of these workers in regard to the
action of the typhoid bacillus upon arabinose. Subcultures
that ferment arabinose rapidly still retain this characteristic
after having been kept on plain nutrient agar for one or two
months.
The enzyme produced by a typhoid bacillus from one of the
sugars, xylose, arabinose, or dulcitol, may be greatly increased
without affecting the production of ferments for the other two
sugars. In anaerobic cultm^s of typhoid bacilli the lack of
oi^gen supply causes a partial inhibition of growth.
DAUGHTER COLONIB8*
Reiner Mtiller (1908, 1911) first showed that Bad. iyphoaum produced
daughter colonies on rhamnose agar. He examined a large niunber of
cultures in this regard an^ found that they all gave rise to daughter
colonies and further that Bad. iyphosum produced daughter colonies in
eight days on agar containing as little as 0.025 per cent of rhanmose
and in fourteen days on agar containing only 0.01 per cent. He sug-
gests that the development of daughter colonies on rhamnose agar
might be utilized in the identification of Bad. iyphosum; the results
* The tenn "daughter colony" is used throughout as signifying the type of
secondary colonies ari^g spontaneously within the substance of the parent col-
ony. The formation of these daughter colonies seems to signify that certain
individual cells within the colony acquire the property of utilising the sugar and
therefore growing with much greater speed than the remaining, bacteria making
up the mother colony.
290 KAN-ICHIRO MORISHIBiA
obtained by Penfold^ Saisawa, and by us as far as they go, indicate
that he was right in concluding that all t3rphoid cultures exhibit the
phenomenon. Muller and Saisawa found that some other bacteria
besides Bad. typhoaum also give rise to daughter colonies on rhamnose
agar.
Penfold (1911) found that the twenty strains of Bad. typhosum inves-
tigated by him all gave daughter colonies on rhamnose neutral red agar
and he noticed acid production in none of the daughter colonies. But
after a number of subcultures in rhamnose broth, he obtained a straia
which fermented rhamnose. Such a rapid fermenter no longer pro-
duced daughter colonies on rhamnose agar and even when it was
passed through thirteen generations of pepton water and plated on
rhamnose agar it still did not give zise to daughter colonies. He
found that the Twort lactose fermenting Bad. fyphosum and
a typhoid culture which had been trained to ferment dulcitol rapidly
both produced daughter colonies on rhamnose agar. Three strains
inoculated on neutral red dulcitol agar yielded daughter colonies as
early as the third day and some of the latter were acid by the fifth
day. Some plates showed as low as 2 per cent of colonies with
daughter colonies, some as high as 50 per cent. Different plates inocu-
lated with the same culture also showed variations within these limits.
Mandelbaum (1912) observed the production of daughter colonies
from B. metatyphi on glycerol agar; from daughter colonies were
obtained organisms which behaved in all respects like Bad. typJumm.
Bernhardt and Omstein (1913) found colonies on dried agar with
irregular outUnes, and nucleus forms like anthrax colonies besides the
normal typhoid colonies. On cultivating in bouillon this organism
produced a film on the surface and was only slightly motile. They
did not observe any phenomena of hypo- or in-agglutinability. These
t3rpes we too have seen on dried plates but they are not real daughter
colonies.
Gildermeister's (1913) typhoid strains produced daughter colonies
on rhamnose agar except m one strain which had been isolated from a
stool. The dysentery bacillus, Shiga-Kruse type and Strong type,
Bad. coll, Bad. alkaligenes, paratyphoid bacilli, Gaertner bacilli, and
cholera vibrios did not produce daughter colonies, but Bad. dyaenieriae,
Flexner type, and six out of fourteen strains of the " Y" type produced
them. Six passages on ascitic agar or transplants over two weeks in
rhanmose bouillon caused typhoid bacilli to grow colonies without
daughter colonies on rhamnose agar.
VABIATIONS IN TYPHOID BACILLI 291
Saisawa (1913) observed daughter colonies of Bad. typhosum when
plated on rhamnose, dulcitol, arabmose (small ones) or er3rthrite agar
after one week. Also he found daughter colonies on plating onrham-
nose agar all of twenty-five strains of typhoid, three strains of Shiga
type of dysentery, three strains of Flexner type, thirteen strains of
Y-tjrpe, two strains of Strong type, two out of three strains of Pseudo-
dysenteriae and none of ten strains of Paratyphoid B, five strains of
Paratyphoid A, ten strains of Gaertner's bacillus, three strains of mouse-
typhoid and six strains of Bad. coU. He could not obtain any varia-
tion of typhoid bacilli in culture media containing phenol or malachite
green or caffein or by heating at 50^C. for one hour.
Daughter colonies have been observed and studied in connection
with cultures of B. anihracis, V. cholerae, Bad. coli, Bad. dyaenieriae,
and other organisms, but they were either caused by sugars not con-
sidered in this paper or were not due to sugars at all.
OUR OWN WORK WITH DAUGHTER COLONIES
A. On sugar media vrithovt indicaior*
On the second day or a little later, in an isolated thin colony,
one or more very small heaped-up yellow or slightly brownish
* The sugars which we used for our work were analysed at the Bureau of Stand-
ards, Department of Commerce, at Washington, D. C. The results were as
follows :
peremt
Arabinose 94. 1
Moisture 1.1 Audubon Sugar School, Baton Rouge,
Insoluble matter 1.4 La., 62 grams arabinose
Undetermined 3.4
Total impurity 4.8
Bhatnnose 89.6
Moisture 9.9 Army Medical Museum, Rhamnose, AMS
Undetermined 0.5
Xylose 100.6
Moisture 0.2 257378, xylose, Difco Standard, Digestive
Ferment Co., Detroit, Mich., U. S. A.
Raffinose 82.5
Moisture 15. 1 Raffinose— no label to show where from
Total impurity 2.4
DidciU
Polarization 0 Dulcite 10 grams Special Chemicals Co.,
Polarization in presence of Not inc.. Highland Park, 111.
borax 0
Melting point 188
292 KAN-ICHIRO MOBISHIMA
yellow granules appear on the surface. Their borders can be
distinctly seen by means of a hand lens or a low power micro-
scope. Day by day they increase in thickness, in size, and in
number, as the mother colonies enlarge. Later a confluent
growth of the daughter colonies may entirely overgrow the
mother colonies.
B. On sugar plates containing indicators
On plates which contain decolorized china blue the daughter
colonies appear, blue in color and inside the mother colony.
After a few days they increase in size, color, and number. The
blue color doubtless is due to the production of acid by daughter
colonies. Ten days or two weeks later, owing to a reduction of
the dye, some of the fully grown colonies may have a brownish
yellow color. The number of large blue daughter colonies that
develop on the plate varies greatly according to the strains of
typhoid bacilli employed, there being in some cases only 1 or
2, and in other cases 50 or 100 colonies.
Agglutination tests made with cultures of daughter colonies
also showed no differences from those done with the original
strain. When we used methylene blue eosin xylose plates
(Holt-Harris and Teague, 1916) the mother colonies showed
a pinkish color, but the daughter colonies appeared as white
dots by transmitted light, some of which soon became black.
These colonies exhibited the same rapidity of growth in the
succeeding dayB that was described in the case of the blue daugh-
ter colonies on the china blue plates.
When we fished daughter colonies from the above plates and
inoculated into the corresponding sugar broth, the latter showed
acid production in twenty-four hours. We plated ten typhoid
strains on eleven different 1 per cent sugar plates. On arabinose,
dulcitol, raffinose, xylose and rhamnose plates from twenty to
fifty strains were planted. The cultures were observed for about
three weeks.
Below are described the variations in growth exhibited on
each sugar medium :
VARIATIONS IN TYPHOID BACILLI 293
I, Arabinoae. Thirty-three strains plated on this medium. The
daughter colonies appear in two to ten days, each colony usually con-
taining many daughter colonies; a few of the daughter colonies fre-
quently developed into large flat, deep blue colonies; all of the strains
tested gave rise to daughter colonies.
S. Dextrin. No daughter colonies appeared.
S. Glucose. Colonies were smaller and denser than on other plates
or control plates and no daughter colonies appeared.
4> DtdcUol. We plated forty cultures and daughter colonies appeared
within two to five days. One or two opaque brownish yeUow daughter
colonies in a mother colony in succeeding days would grow so rapidly
in size that sometimes the mother colony would be entirely covered.
Furthermore, there is a tendency toward color reduction as the growth
increases.
5. Galactose. Colonies were smaller than on control plain plates and
no daughter colonies were produced.
6. Glycerol. We used 3 per cent glycerol plates for this purpose
and obtained colonies which were very thick, opaque and yellowish
brown in color. Plates containing China blue produced pale colonies
on the first day, which became deep blue later. The color was reduced
by the thick growth. No daughter colonies developed.
7. Inosite. No daughter colonies.
8. Lactose. No daughter colonies were seen.
9. Mannitol. No daughter colonies developed.
10. Maltose. There was good growth in point of size and thickness,
but no daughter colonies were visible. Twenty strains were plated.
II. Raffinose. No daughter colonies developed, but ten days later,
they showed papillif orm colonies which did not increase in size nor in
thickness on further incubation.
IS. Rhamnose. All thirty tjrphoid strains which we tested on 1/10
per cent rhamnose plates gave rise to daughter colonies as well as on 1
per cent rhamnose plates. On the latter and on 2 per cent and 3 per
cent plates, we could see many large opaque brownish yellow colonies
scattered here and there with small daughter colonies and 1 per cent
rhanmose Endo plates showed the same appearance.
The best method thus far developed for isolating typhoid bacilli from
stools consists in plating upon a lactose medium containing brilliant
green and an indicator for acid production. It seemed that a further
improvement would be introduced by supplying a positive character-
istic to the typhoid colonies instead of relying solely on the absence
294 KAN-ICHIBO MORISHQCA
of acid production. We attempted to accomplish this resxilt by add-
ing rhanmose (0.1 to 0.25 per cent) to brilliant green lactose agar, in
the expectation that the daughter colonies within the typhoid colonies
would furnish such a positive characteristic; however, we soon per-
siiaded ourselves that this method has no practical value.
13. Salicin. No daughter colonies developed.
14' Sucrose. No daughter colonies developed.
15. Xylose. Fifty strains were planted. All xylose slow fermenters,
thirteen in niunber, gave rise to daughter colonies on plates containing
from 2 per cent to 0.04 per cent of xylose. The rapidly fermenting
strains did not give rise to daughter colonies.
Sometimes xylose plates which contain 0.25 per cent glucose or which
contained brilliant green eosin (Teague and Clurman) were used without
interfering with the growth of the daughter colonies.
16. Control plain platea.
Some typhoid bacilli produced papillae-like forms on plain
plates two or three weeks later when the plates were nearly
dried up; such papillae sometimes occur also on plain plates
inoculated with paratyphoid bacilli or Bact. coli. They never
increase in size or in thickness. Therefore, we could not consider
them true daughter colonies.
Under anaerobic conditions, we tested four strains, xylose
slow fermenters (Rawling's, C-59, 57 and C-188) on 1 per cent
xylose china blue plates; only two strains (C-59 and 57) produced
daughter colonies on the eighth day; while under aerobic con-
ditions^ all four strains produced daughter colonies within three
to five days.
RELATIONSHIP BETWEEN RAPID AND SLOW XYLOSE FERMENTEBS
Kowalenko (1910, 1911) obtained Bact. coli cultures from Neisser,
Massini (1907) and Burk^and tried to separate fermenters and non-
fermenters from them after plating on Ekido plates, and also from cul-
tures which he isolated from a fever patient's stool on the Endo plate.
He always obtained red-colored colonies after plating on Endo plates
from a red-colored colony on the Endo plate, but he obtained white colo-
nies and red colonies from a white colony on replatiog just as we
observed above. He reached the conclusion after more study that
mutation of bacteria could not be efifected by influences from without
VAKIATIONS IN TYPHOID BACILLI 295
by cultivation at various degrees of temperature, by long cultivation,
by the addition of chemical substances, or by passing through the ani-
mal body. Saisawa (1913) tried in the same way to separate daughter
colonies and mother colonies on plating typhoid bacilli but in vain.
It seemed to us that similar studies made with tjrphoid bacilli
in regard to the separation of rapid and slow xylose fermenters
from a single original strain might prove of great interest. Ac-
cordingly we made subcultures of two xylose slow fermenters
two or three times on plain plates, each time fishing a single
colony and planting from the single colony in 1 per cent pepton
water. Then from the last suspension of a single colony we
plated on 1 per cent xylose plates containing china blue or
methylene blue-eosin. At the same time, a loopful of suspension
was inoculated to 1 per cent xylose broth containing china blue
indicator as a control. Repeated subcultures were made by
this method in the hope that after some generations we might
get a strain of non-xylose fermenters. We did not obtain such
results, however. Charts of the subcultures obtained from the
two strains follow :
Strain 57
This strain was always plated on 1 per cent xylose containing
methylene blue and eosin.
O— Original
# ■> quick xylose fermenter in twenty-four hours.
O mm slow fermenter.
JOUBXAL OV BAOmUOLOOT, TOL. TI, NO. 8
296 KAN-ICHIBO MOBI8HIBCA
Day an which acidity appeared in xylaee broth
Oiiginftl~-fifth day
I — fourth day
II— fifth day
in— third day
IV— third day
Arabic numerals » interval in days between the appearance of a colony and
subculture from it on 1 per cent xylose media containing indicator.
Roman numerals » number of generations.
We obtained only once a few pink colonies from a xylose
fermenter. Thereafter we obtained only black colonies from
xylose fermenter plates.
RawKng^s
This strain was planted on 1 per cent xylose plates containing
decolorized china blue.
O — Original
Production of acidity
Original — seventh day
I — sixth day
II— fifth day
III — ^ninth day
IV — seventh day
We could not obtain any nonfermenter from the cultivation
on xylose plates.
From quick fermenters which we had isolated slow and rapid
types were readily obtained.
VARIATIONS IN TTFHOID BACILLI 297
II. Variations in Reaction to Sebxtm
INA6GLUTINABILITT AND AGGLUTINABILITT OF TYPHOID BACILLI
Agglutinability of tjrphoid bacilli isolated from specimens
(blood, feces, urine, or bile) from the patient may vary greatly,
depending to some extent on the number of culture generations
for which they have been carried on artificial media. This
has been reported by many workers (Forster (1897), Johnson
and MacTaggart (1897), Mfiller, Eisenberg (1903), Sawyer (1912)
and others). Thus, lack of agglutinability of the isolated bacilli
in early culture generations is sometimes misleading in regard to
diagnosis.
Schmidt (1903), for instance, erroneously reported typhoid
bacilli as paratyphoid, owing to their inagglutinability. This
inagglutinable state, acquired by the bacilli in the human body,
can be easily produced by artificial means, such as cultivation
on antityphoid serum broth. Such observations were first
reported by Ransom and KitAshima, and by Mtiller. The
former observed, in 1898, that the cholera spirillxmi lost its
agglutinability when they cultivated it in anticholera serum,
and the latter observed the same phenomenon in t3rphoid bacilli
in 1903. The literatiure upon this subject is extensive and has
been compiled in the articles of Eisenberg, Mtiller, and others.
As early as 1896 Metchnikoff and Bordet showed that cholera spirilla
could partially lose their agglutinability under certain circumstances.
Bail (1901) made similar observations with the typhoid bacillus, and
Kirstein (1904) showed that cultivation at various temperatures
could diminish the agglutinability of bacteria. It has been found,
indeed, that organisms isolated from different cases of the same dis-
ease often varied considerably in their agglutinability in one and the
same immune serum. This was noted by Grassberger and Schatten-
froh (1900) in their studies upon anthrax. Bordet and Sleeswyk (1910)
studying the whooping cough bacillus showed that when a horse is
immunized with a whooping cough baciUus which has been grown upon
blood media, the serum of this animal wUl powerfully agglutinate this
strain, but possesses little or no agglutinating activity against the same
strain habituated to growth on plain agar, an observation which they
298 XAN-ICHIBO MORISHUCA
interpret as meaning that the agar strain has lost its receptors for the
absorption of the specific agglutinin and this inability to absorb agglu-
tinin they, indeed, demonstrated by experiment. Park and his col-
laborators have studied these relationships particularly with the
dysentery bacilli, and Park and Williams (1917) make the following
statement:
''The maltose fermenting paradysentery bacillus of Flexner was
grown on each of eleven consecutive days in fresh bouillon solutions
of the serum from a horse immimized through repeated injections
of the bacillus. The solutions used were 15, 4 and 1.5 per cent. The
serum agglutinated the culture before its treatment in dilutions up to
1 to 800, and was strongly bactericidal in animals. After the eleven
transfers the culture grown in the 15 per cent solution ceased to be
agglutinated by the serum and ceased to absorb its specific agglutinins.
The cultures grown in the 15 and 4 per cent dilutions of serum agglu-
tinated well in dilutions up to 1 to 60 and 1 to 100, and continued to
absorb agglutinins. The recovery of the capacity to be agglutinated
was very slow, the cultures being transplanted from time to time od
nutrient agar; after growth for sixteen weeks, during which it was
transplanted forty-three times, it agglutinated in dilutions of 1 to 200.
The culture grown in 4 per cent agglutinated in 1 to 500 dilution, and
the one in 1.5 per cent in 1 to 800."
And in their new edition (seventh edition, (1920)) they say:
''The agglutinogenic power, or power to stimulate the production of
other antibodies, is not lowered when bacteria become less agglutinable."
The presence of a capsule may interfere with or prevent agglutination.
The capsule, developing best in body-fluid or tissues is probably a pro-
tective substance. Porges (1905a,b) has outlined a method for the
removal of the capsule as a preliminary to agglutination.
Eisenberg (1913) studying a typhoid strain carried along in blood
bouillon for a considerable period, found similar development of inag-
glutinabiUty. And Schmidt (1903) has cited a caae of a typhoid
bacillus isolated from hmnan disease in which inagglutinability led to
prolonged error of diagnosis. Bail working with typhoid bacilli culti-
vated from the peritoneal exudate of infected guinea pigs showed that
under such conditions the organism loses a considerable degree of its
agglutinability and attributes this to the development of a capeule-like
substance which insulates the bacteria against the antibodies.
A definite loss of agglutinability under similar circumstances was
noted by Zinsser and Dwyer (1918) in connection with experiments
VABIATIONS IN TTFHOID BACILLI 299
upon proteotoxin, but without their finding an3rthing in the nature of
a capsule which could explain the phenomenon. Ransom and Kita-
shima, Miiller (1911), Hamburger, Walker (1904) and several other
workers have also produced inagglutinability by cultivating on sera
containing agglutinin. Forges and Prantschoff (1906) used this method,
obtaining irregular results, and attribute this to individual variations
in the strains used.
Moon (1911) produced two substrains of a single typhoid bacillus
culture by the Barber method, one of wliich agglutinated with anti-
typhoid serum and the other did not. A few generations later both
bacilli showed equal agglutinabiUty.
In Zinsser's book (1918) Infection and Resistance, he states:
''This lessened susceptibility to antibodies is noticeable not only in
strains cultivated from the body in disease, but can be produced arti-
ficially by cultivating the bacteria on inactivated, homologous immune
serum. Such strains may not only increase in virulence, but lose in
both agglutinability and susceptibility to bactericidal effects."
Sacquepee (1901) obtained similar variations by keeping the organ-
isms in collodion sacs in the peritoneal cavity. Sawyer (1912) iso-
lated a strain from a t3rphoid carrier's stool which did not agglutinate
with a serum dilution of 1 to 50, but after 11 transplants within two
weeks the culture became agglutinable. The same phenomenon has
been observed by Scheller (1908).
Recently Gay and Cla3rpole (1913) studying the typhoid bacillus,
found that when they produced the carrier state in rabbits the organ-
isms isolated from such rabbits (Culturally true typhoid bacilli) failed
completely to agglutinate in serum produced with a stock culture and
which agglutinated such stock cultures in dilutions as high as 1 : 20,000.
The blood and bile cultures which were inagglutinable by means of the
ordinary antiserum, were readily clmnped by means of a serum pro-
duced by immimizing rabbits with cultures grown on a blood agar
medium. If confirmed, these observations, like those of Bordet and
Sleeswyk, would indicate a complete alteration of antigenic properties
by means of cultivation on blood media, and prolonged residence in the
animal body; for the serum produced with the cultures upon blood, not
only agglutinated these cultures, but also the plain agar growths, and
if the cultures on blood were carried along for some generations on plain
agar, they again became agglutinable by the serum produced with the
plain agar culture. Gay (1914-15) uses this observation to explain the
occasional inagglutinability in ordinary sera, of typhoid bacilli recently
300 KAN-ICmBO MOBISHIMA
isolated from human cases, and emphasizes the diagnostic difficulties
which this may occasion. Bull and Pritchett (1916), however, repeating
the work of Gay and Claypole found that 25 generations of cultivation
in separate series upon plain agar and upon blood agar did not produce
appreciable agglutination differences in a typhoid strain. They carried
this out with 57 different strains of typhoid bacilli. Nichols too has
contradicted the claim of Gay and Cla3rpole that gall bladder infec-
tions could be regularly produced in rabbits by injection of typhoid
strains grown on blood agar, an observation which would further
strengthen the opinion of a fundamental change in reaction to the ani-
mal body and its fluids produced by cultivation upon blood constitu-
ents. Our own observations (in which we cultivate the typhoid strains
upon normal rabbit's serum) also indicate that such a procedure does
not exert any appreciable effect upon their agglutinability. Thus the
results of Gay and Claypole concerning the inagglutinability of cul-
tures obtained from infected human beings and rabbits would corre-
spond in principle with the investigations of other workers. But
the alterations obtained by them by simple growth upon normal blood
agar cannot be accepted as conclusive in the light of contradictory
results of Bull and Pritchett and of Nichols, and also in the light of our
own failure to obtain appreciable changes in strains carried for many
generations on normal rabbit serum broth.
It appears from these researches (and many others which
might be cited) that the problem has not yet been solved in all
particulars. But the general weight of evidence indicates that
cultivation in the presence of specific senmi antibodies alters
the strains in the direction of lessened agglutinability.
The following experiments upon this phenomenon were carried
out by us:
Materials used in agglvtinaiion teds
1. Broth. This consisted of 0.1 per cent Liebig's meat extract; 1
per cent pepton (Difco ); and 0.5 per cent sodium chloride per liter;
its reaction was adjusted to pH 7.0. It was sterilized in the autoclave
at 15 pounds pressure for fifteen minutes.
2. Antityphoid serum from rabbits immunized against monovalent
strain of typhoid bacilli (Rawlings, C-51, no. 3, Cohen, C-188). Each
serum titre was 1:10,000 or 1:20,000 for our standard laboratoiy
strains.
VABIATIONS IN TYPHOID BACILLI 301
3. Normal rabbit serum. Serum obtained from normal rabbits and
inactivated at 56^0. for half an hour. About 1 cc. of each mediiun was
placed in small test tubes used for Wassermann work under strictly
aseptic precautions, and kept in an ice-chest.
4. The strains used were plated on plain plates three times, and
each time one single colony fished to 0.85 per cent sterile salt solution
and from this plated on another new plate.
Technique
Stock cultures or newly isolated cultures as described above were
suspended in 1 per cent pepton water, and transferred to serum broth
or broth; thence retransf erred from serum broth to new serum broth
or from plain broth to new plain broth, by using a small platinum loop;
then incubated at 37**C. ' Usually after twenty-four hours' growth the
culture was plated on plain agar or implanted on slant, using a platinum
needle or a very small platinimi loop (in the use of the loop we took great
precautions against including any serum broth) ; after standing over-
night in the incubator at 37^0. the growth was evenly emulsified in
0.85 per cent salt solution (the bacterial growth always covered the
entire surface of the slant). Special care was taken to have the
emulsions of the cultures of as uniform a thickness as possible and for
this purpose a tube of typhoid bacterial emulsion was kept for
comparison.
Graded dilutions of the serum were made with 0.85 per cent sodium
chloride solution and ranged from 1 : 50 to 1 : 24,300. Half a cubic centi-
meter of each dilution was transferred to small agglutination tubes
and an equal amount of bacillary emulsion was added to each tube
and also to a salt solution control.
The results were recorded after two hours' incubation at 37®C. and
again after standing overnight in the ice-chest. The controls never
showed agglutination. By this method cultures which had been grown
on serum were allowed to develop for one generation on agar without
serum before their agglutinability was tested. Controls were treated
in the same way.
The serum media were occasionally tested for loss of agglutinating
power, and were controlled for contamination by plating on plain plates
or Endo plates or by inoculation in sugar media, but results were
always negative. Such control cultures were made in sugar media
(namely, xylose, arabinose, glucose, maltose, manni^l, lactose, sucrose,
302 KAN-ICHIRO MORISHBiA
rhamnose, raffinose, dulcitol) in broth, in litmus milk, and in 2 per cent
glycerol; or plated on Endo plate; always, as stated above, with nega-
tive results.
STRAINS MADE INAGOLUnNABLE BY ARTIFICIAL MEANS
I. Antityphoid rabbit serum (Rawling's strain), with a titre
of 1 : 10,000 for the homologous and for other laboratory strains,
was mixed in proportions of one part of the serum to four parts
of the broth in small test tubes. In the course of the e3q)en-
ments, this serum being exhausted, another antityphoid serum
(made with strain C-51) with a titre of about 1:10,000 was
substituted.
The same lot of broth was used in the controls.
The stock strains used were ^'Rawling's," "C-188," and
"Cohen." These were prepared in the manner described above
and inoculated into the media.
1. Rawling's strain. Within thirty-eight days this strain was
retransplanted twenty-four times from one tube to another, in
two parallel series, one upon antityphoid serum broth, the other
on plain broth. During the first ten days, it was transplanted
every day and later at intervals of several days. AgglutinabiUty
was tested eight tunes during this period with the same serum.
Chart 1 shows the results.
As is shown by chart 1, the power of agglutinability in dilution
of 1:8000 fell to 1:300 after three days, and twenty-four days
later, after fifteen transplants in fresh serum media, the agglu-
tinability was recovered. After that there was no remarkable
difference between control and serum cultures, although the
culture in serum broth was always somewhat lower in agglutin-
ability than the control. Tke first readings of the serum broth
culture after two hours' incubation always showed much lower
agglutinability than the control cultures until the expiration of
thirty-five days. The astonishing feature of this experiment was
the fact that the serum strain seemed to recover its agglutinability
after prolonged cultivation on sermn, though at first it had lost
it. For this reason, on and after the twenty-third day, we used
VABIATIONS IN TTPHOID BACILLI 803
the other sera ''C-51" and ^'3/' for agglutination tests, but did
not observe any striking difiference between Rawling's serum
and the other two sera in agglutmating Rawling's strain.
2. ''C-188'' strain was tested in the same way as the Rawling's
strain.
ODart I
RawUng strain against Rawllng'8 aerua antityphoid
j^
Dilution of serum
20^000
10^000
8,000
6,000
3,000 ;\ / ,'
2,000 *.\ / y
1,000 \ ^-^
900 \
800 » f- -^
600 '• /. .'
400 y * ;
300 V
100
50
0
nay of agglutination test at3 6 1024-273338
once
KufflDer of transplants 0 2 5 9 15162224
Maries
i > Control culture plain "broth culture
> ^ 24 hours reading \ «^^,« «^.<4^ ^„-i*„^^
2 hours inouhatlon J ^^^"^ "^^^^ ^^^^^^®
In this case, we made agglutination tests eleven times within
sixty-three days. Its agglutinability feU from 1 : 8000 to 1 : 3000
after one day's cultivation in serum media. Three days later
agglutination occurred only in dilution of 1 : 100. Six days later,
304 KAN-ICHIBO MORISHnCA
it was below 1 :50. On the twenty-seventh day it rose to 1 :300
and after the thirty-fifth day to 1 : 20,000. Thereafter, from the
thirty-fifth to the sixty-third day, which was the last day of this
experiment, the serum strain and the broth control remained
entirely parallel. Other sera, C-51 and 3, were frequently used
after the twenty-third day but no differences were seen between
Rawling's senun and the other two sera.
C&art XZ
conan stzaln agglutination against Rawling't antltyp&old serum
-.-\/^
Dilution of serua
20,000
10,000
6,000
6,000
3.000
2,000
1,000
900
800
600
i^OO
300
100
50
Days of agglutination test at I 3 61Q2324273338)^7'»963646671737785
onoe
Tlnss transplanted on media 0 1 Z ^ 9I3l5162224283031323ii3639^043
— -^ 21^ Hours reading, oontrol plain Drotn oultore
- --• 2 nours reading S
' 2i» Hours readlngh****^ ^'^^ oultur^
3. Cohen strain was tested in the same manner. We tested
its agglutinability twenty-three times within eighty-five dajrs,
within which period we made forty-three transplantations. The
results are shown on the next chart.
After seventy-one days this strain recovered its agglutinability
gradually and at seventy-seven days it had almost completely
recovered this property. But readings two hours after incu-
bation were always slightly lower than the twenty-four hours'
readings. On the fourth day very slight agglutination in dilu-
VARIATIONS m TYPHOID BACILLI 305
tions of 1 : 50 and 1 : 100 occurred, visible only with a lens. After
that not the slightest agglutination could be seen in any dilution
up to 1:50 until the forty-ninth day. On the forty-ninth day
slight agglutination was visible by lens up to 1:300 dilution,
and on tiiie sixty-fourth day, we could recognize good agglutina-
tion in 1:50 dilution of serum. Then within about two weeks
it reached ahnost the highest dilution of the serum attained by
the control culture. Nine tests were made with the Rawlings
serum. On and after the twenty-third day, we tested its agglu-
tinability five times with C-51 serum as well as with the Rawling's
serum. Readings at the end of two hours showed no agglutina-
tion for the first four times but agglutination appeared in 1 : 100
dilution of the serum after the forty-fifth .day. In twenty-four
hours' readings no agglutination appeared in 1 : 50 dilution of
s^iun imtil the twentynseventh day while on the thirty-third
day, and after, it occurred in a serum dilution of 1 : 900.
During the same period we tested the strain seven times with
antityphoid serum (no. 3). Two hour readings showed that no
agglutination appeared in 1 : 50 dilution of serum imtil the forty-
ninth day. On the sixty-fourth day good agglutination appeared
in 1:100 dilution. In twenty-four hours' readings imtil the
thirty-third day no agglutination was seen in 1:50 dilution.
From the thirty-seventh to the sixty-fourth day it always showed
agglutination up to 1 :300 dilution of serum.
Agglutinations of control cultures by each serum ranged from
1:8000 to 1:10,000.
In all experiments done with difiFerent sera (Rawling's, C-188,
and Cohen) when we changed the serum media there was a slight
tendency toward agglutination in the first generation on the
new serum. After two or three generations in the new serum
media this tendency disappeared.
II. We controlled our experiments with normal rabbit serum
broth in place of antityphoid serum broth media. Four parts
of broth and one part of normal rabbit serum (inactivated by
heating at 56''C. for half an hoiu*) were used for this purpose and
a series of agglutination tests carried out with the same strains
and in the same manner as before.
306 KAN-ICHIBO MOBI8HBCA
Agglutination tests of each culture were carried out five times
within forty-three days, using Rawling's serum for the tests.
Twenty-eight transplants were made during this period.
III. SiQce the experiments done so far seemed to show a
delicate difference between the reactions of individual strains
with different antityphoid sera, we decided to repeat them carry-
ing a single tjrphoid strain both on an homologous serum and
on an antityphoid serum produced with another stock strain.
For this purpose we immunized two rabbits, in one case using
no. 3 culture and in the other C-51. The former is a rapid
xylose fermenter and the latter a slow xylose fermenter. We
obtained sera which agglutinated our laboratory strains and their
own specific strains in dilution of 1:15,000. Cultivation in
normal serum in no case changed the agglutinability of the
bacilli, which remained parallel in every way to that of the
cultures carried on plain broth. Serum me^ was again pre-
pared (one part serum to four parts broth) and tubed in small
tubes. Experiments as described above were then carried out.
(1) Strain C-51. After two days' cultivation both in its own
serum broth and in no. 3 serum broth, this strain slightly lost
in agglutinability (1:8000). This continued for twelve days,
but on the fifteenth day both series recovered agglutinability
equal to that shown by the control cultures.
In no. 3 serum broth its agglutinability was lowered slightly
more than by growth in the homologous C-51 serum broth,
but there was no very considerable difference between them.
(2) Strain no. 3. This strain was tested in the same way as
C-51, by cultivation in its own serum broth and in C-51 serum
broth. On the third and seventh days inagglutinability on serum
no. 3 was most marked (1 : 100) both for the cultiu^ carried on
no. 3 serum and for the one carried on C-51 serum. Both
gradually recovered agglutinability and reached normal agglutin-
ability on the thirty-sixth day.
When we used C-51 serum for agglutination tests similar
residts were obtained. On the third day both series reached
the maximum point (1:2000) of inagglutinability. Then they
gradually recovered, although in this case recovery to normal
agglutinability was delayed for twenty-two days.
VABIATIONB IN TYPHOID BACILLI 307
This experiment showed that typhoid strains lose agglutin-
abUity in the same d^ree, whether cultivated in a serum broth
of their own specific immune serum or on a serum immunized
against other strarns. No difference was observed between
rapid xylose fermenters and slow xylose fermenters.
IV, The above experiments were performed with old stock
cultures. We next repeated these tests using freshly isolated
strains. Two strains (Owen and Boyle) which were obtained
from typhoid carriers' stools were used after three generations
on artificial media.
The media consisted of four parts of broth and one part of
Rawling's or C-51 serum, the agglutinating titre being 1 : 15,000.
The Owen strain was cultivated in Rawling's serum and C-51
serum broth and transplanted into fresh media six times in seven
days. It reached its maximum inagglutinability (1:900) in
seven dajrs with the same serum in which it was grown. When
tested with the other serum its loss of agglutinability was not
so great. A few dayB later both cultures in Rawling's serum
broth and in 051 serum broth recovered their agglutinability.
Observations were made with the Boyle strain in the same
manner as with the Owen strain. In this case the maximum
point of inagglutinabiUty in Rawling's serum broth and in C-51
serum broth was reached on the fourth day.
On carrying out agglutination tests with RawUng's serum one
strain (Rawling's serum culture) continued its inagglutinability
(1:300) at least ten days, while the other culture in C-51 serum
broth regained its agglutinability on the seventh day. The
other tests with C-51 serum ran almost parallel. The maximum
point of inagglutinability (1:900) was reached on the fourth
day and agglutinability was recovered on the seventh day.
In the foregoing experiments observations were made concern-
ing the character of the growth of tjrphoid bacUli in serum broth
in vitro. During the first few dajrs the bacteria grew like a
mass of cotton at the bottom of the tubes; later when the bacteria
had partly recovered agglutinability some organisms grew on
the surface of the media, forming a film, as well as at the bottom.
Up to this point the mass of bacteria is not easily broken up by
shaking, but after recovery of agglutinability it becomes very
308 KAN-ICHIBO MORISHDCA
easy to break up the spongelike growth. A few days later the
broth becomes turbid, at first, with a few clumps of agglutinated
bacteria, and later only a imiform turbidity is present; in the
last stage, at least one month later, the cultures grow slightly
more tiu'bid in the tubes, and about two months later, the general
turbidity of the cultures is only slightly less marked than that
of control cultures in broth.
The experiments just described were carried out in concen-
trated antitjrphoid serum media. It seemed important to
observe what influence would be exerted on tjrphoid bacilli by
cultivation in broth which contained a very low percentage of
antityphoid serum. This might perhaps tell us what influence
would be exerted upon the bacilli in the early stages of typhoid
fever.
We prepared a niunber of broth tubes containing Rawling's
serum in a proportion of 1:10,000. The titre of this serum
against Rawling's culture was 1:10,000. We used two strains
for these observations, one the Rawling's strain, the other a
cultiure designated as Sanguist, which had been freshly isolated
from a patient's blood.
We carried out agglutination tests eight times within thirty-
three days during which we made twenty-two transplants.
Rawling's strain showed practically no change, a result distinctly
in contrast with its loss of agglutinability when grown in con-
centrated serum broth. The Sanguist strain diminished in
agglutinability after three days although the difference between
the serum culture and the control broth culture was not great
After thirty-two transplants thirty-three days later, it regained
agglutinability completely. In short, in this experiment a
small amount of antityphoid serum in media did not produce
any marked change in agglutinability of tjrphoid bacilli.
When the serum contained blood cells the typhoid bacilli
acted haemoljrtically and reduced the medium from a reddish
color to yellow in twenty-four hours.
Several varieties of sugar media and litmus milk were inocu-
lated from the cultures described above and no differences
appeared between control cultures and serum broth cultures
within three weeks.
VABIATI0N8 IN TYPHOID BACILLI 309
A60LXTTININ ABBORPTEON TESTS OF XYLOSE QXHCK FEBMENTER
AND XYLOSE SLOW FEBliENTEB
The next e3q>eriments were undertaken to determine whether
xylose quick fermenters and xylose slow fennenters differed in
regard to serum reactions.
We immunized rabbits against the xylose fermenting strains
"Cohen" and "no. 3," and against the xylose slow fermenters,
C-51, Rawling, and C-188. The serum titre of each strain was
between 1:10,000 and 1:15,000 for each strain. Three agar
slants of xylose quick fermenter twenty-four hours old were
prepared and a suspension in 5 cc. of 0.85 per cent salt solution
made. To each suspension was added 5 cc. of each correspond-
ing serum in dilution of 1 : 50. The tubes were then incubated
for three hours at 37°C. After that, we centrifuged them for
half an hour at high speed, and pipetted off the supernatant
fluid. This was then made up with 0.85 per cent salt solution
into a series of dilutions ranging from 1:100 to 1:16,200. To
0.5 cc. of each dilution was added 0.5 cc. of the su£fpension of a
xylose quick fermenter, and similarly to another series of dilution,
0.5 cc. of a suspension of a xylose slow fermenter was added.
The two series were incubated for two hours at 37^0., and allowed
to stand overnight in the ice-chest. The results were read
before placing in the ice-chest and again the next morning.
As controls, agglutination tests were carried out using the original
strains and fresh imabsorbed serums.
After absorption of both sera by slow xylose fermenters we
found that practically all agglutinin had been removed. The
only exception to this was a slight persistence of agglutinin in
the tube containing the 1 :200 dilution. Vice versa we absorbed
the serum produced with xylose quick fermenters by means of
a xylose slow fermenting organism and then looked for traces
of agglutinin by adding suspensions of both xylose rapid fer-
menting and xylose slow fermenting strains. The results were
the same as those obtained above.
Control tests gave negative results.
Xylose slow fermenters and xylose quick fermenters are there-
fore not serologically different.
310
KAN-ICHmO MORISHIMA
It is worth noting in this connection that lieut.-Col. H. J.
Nichols tells us that he has found no difference between rapid
and slow xylose fermenters in regard to their virulence for
rabbits.
Having determined the peculiar conditions imder which
tjrphoid bacilli become inagglutinable and subsequently regain
their agglutinability, without removal from the specific iTnTnimA
serum, it seemed important to determine whether this was due
to inability to absorb the agglutinins or possibly whether it had
some relationship to a changed reaction to electrolytes in solu-
tion. Also it seemed important to determine whether or not
something analogous to an insulating capsule as described by
Bail, Kuhnemann and others was responsible for the phenomenon.
Accordingly we first proceeded to carry out agglutinin absorp-
tion tests as follows:
a. Agglutinin absorption test
This test was carried out several times using the Cohen strain
culture in serum broth for sixty-six days with 49 transplants in
serum broth (see chart 2). As controls Cohen and C-188 strains
were cultures in plain broth. The serum used was usually
Rawling's, sometimes others. The technique employed was that
described in the section on agglutinin absorption tests of xylose
quick fermenter and xylose slow fermenter. The results follow:
TTVHOID STRAXm BSVOBB
IBBATIUBMT BT THB
BBBUM
Cohen serum broth
culture
Cohen broth cul-
ture (control)
C-188 broth culture
(control)
Dii.QnoN or BAWLma*8 AimTTraoiD sBBini
100
++4-
+++
800
+ + +
+ +
400
+++
+ +
800
++ +
+ + +
1,000
+++
+++
4.800
+++
+ + +
14.150
+ +
+
43.200
oojr*
+++ » complete agglutination.
++ "■ good agglutination,
-h "■ good agglutination but still cloudy.
— ■• negative. No agglutination.
VABIAOIONB IN TTPHOID BACILLI
311
Results are recorded after two hours incubation at 37^C. and stand-
ing in an ice chest over night. Hereafter we shall use the following
abbreviations:
Cohen S » Cohen strain cultivated in serum broth
Cohen B = Cohen strain cultivated in broth (control)
C-188 B = C-188 stram cultivated in broth (control).
Tests done in Rawlings serum after absorption of this serum in dilu-
tion of 1:100 at 37**C. for three hours with the "serum" and the
broth" strains respectively:
t(
(a)
BACrSBXAL B17VB1CBIOH
BT COHBX 8
aAum
coxr-
200
400
800
1»600
8.200
0.000
28.800
TBOL
Cohen S
+ + +
+ + +
+ + +
+ + +
+ + +
+ + +
—
Cohen B
_
C.188B
^^
(b)
BAOriBZAI. BUBPBIIBXOH
DILimOM or BAWLZVa'S 8BBU1I PBBVIOUSLT TBBATBD
BT COHEN B
■ALDTB
CON-
200
400
800
1.000
3.200
0.000
28300
TBOL
Cohen S
*"
—
—
—
—
_
Cohen B
_
C-188B
>
Tests with C-188 serum
Before absorption
BAGTBHXAL SUBPBNBXON
DXLimOM or 0-188 ^OfnTTPHOXD bbbum
BALma
CON-
100
200
400
800
1.000
4.800
14.400
48.800
TBOCi
Cohen S
■1-++
+++
++ +
+++
+++
+ + +
+ + +
+
_
Cohen B
^^
C-188 B
^^
After absorption of C-188 serum in dilution of 1 : 100 at 37*^C. for three houn.
312
KAN-ICHIBO M0BI8HIMA
(»)
DiLDTioif or 0-188 BBBTni raanouiLT imowb
WITH OORBV •
ffTjm
BAomoAL Bxmrmmuon
GOlf-
300
«0
800
1,000
3,100
•400
18,800
TBOIt
Cohen S
+++
+++
+++
+++
+++
+++
+++
+++
+++
++ +
+++
++
+
Cohen B
_
C-188B
_
(b)
BACTBBIAL ■DVBIIKOV
•
DiLunoir or 0-I88 sbbum pbitiodilt abbobbbd
WITH COHBB B
OOH-
200
400
800
1,000
s;m»
9.000
»JM
Cohen S
-
■■■
^^
•^
—
"■"
_
Cohen B
^^
C-188B
^^^
Teste with "Cohen" serum
Before absorption of serum
BACTBBXAx. Bummszoir
Cohen S .
Cohen B.
C-188 B .
DiLunoir OF "oobbk" AjfimrBOXD sbbum
aoo
+++
400
800
1.000
8.200
+ + +
8.400
12.800
28.800
After absorption of Cohen" senimi diluted to 1 : 200 at 37**C. for three hours
(a)
Cohen S .
Cohen B
C-188 B .
rtf
DILUTXOir OF "OOKBV" SBBUM WXTR COHBB B
400
+ + +
+ + +
800
++ +
1.600
+++
8.200
+++
8.400
++
12,800
26,800
(b)
DILUnOV OF "OOHBH" SBBUM WXTR OOBBH B
■AUBB
GOIK
400
800
1.800
8.200
6,400
12.800
25.800
TBOt
Cohen 8
+ •
^^
^^
—
^^
•■"
"—
Cohen B
C-188 B
• Slight.
VARIATIONS IK TYPHOID BACILLI 313
These experiments showed that Cohen S cultures did not
absorb the agglutinin of any of the three antityphoid sera.
The work of Bordet has demonstrated the essential importance
of electrolytes in agglutination, and the studies of Neisser and
Friedemann, Friedberger and others have shown that whereas
small traces of salts will flocculate bacteria that have absorbed
agglutinin, it requires very large amounts of the same electrolytes
to flake out normal (insensitized) organisms. Since the researches
of Neisser and Friedemann especially have shown that to a
certain extent there is a relationship between the degree of
sensitization and the amounts of salt necessary to bring about
agglutination, we considered it of interest to determine by com-
parative tests the differences in sodium chloride concentration
necessary to flake out, on the one hand, the Cohen serum strain,
and on the other, the Cohen broth strain after both had been
treated with homologous serum. This would show whether or
not any trace of agglutinin had been absorbed by the Cohen S
strain in the process.
Typhoid bacterial suspensions in Rawling's serum were centri-
fuged for thirty minutes and all the supernatant fluid decanted
off for another agglutination test; the residue in both centrifuge
tubes, one of them containing Cohen S and the other Cohen B
strains was poured into a few centimeters of 0.85 per cent salt
solution and without centrifuging but after slight shaking, all
the fluid was decanted from the tubes, leaving a mass of bacteria.
This was worked into an emulsion by means of a glass rod, and
distilled water added drop by drop. The graded dilutions of
the 20 per cent sodiiun chloride were prepared, to range from
20 per cent to 0.025 per cent. A half cubic centimeter of each
dilution was transferred to small tubes and a half cubic centi-
meter of the above bacillary emulsion in distilled water was
added to each tube and also to a distilled water control. The
results were as follows :
The percentage shown below is the actual percentage after
mixing salt solution and watery bacterial suspension :
314
KAN-ICHIEO MORTflHTMA
Cohen S emulsion
Cohen B emulsion
10
4-
+
8
+
4-
+
+
+
+
+
3
+
+
+
+
0.9
+
+
0.8
0.7
+
+
+
+
0.0
+
0.5
+
0.4
0.3
0.2
+
0.1
+
8
+
+
This experiment shows that the Cohen S strain absorbed either
no agglutinin at all or so little that it could not be demonstrated
by strong solutions of sodium chloride.
We have now shown that the typhoid bacillus^ which loses
agglutinability after prolonged cultivation on immune serum,
becomes inagglutinable because of its f ailm^ to absorb agglutinin.
It was next desirable to determine, if possible, whether this
inability to absorb antibody was due to an ectoplasmic insulation
substance identical with or analogous to a capsule, since capsule
formation in other bacteria has been shown to protect against
seriun effects. In spite of repeated attempts we never succeeded
in demonstrating a capsule in our serum strains by staining
methods. However, Bail and others have suggested that such
capsular materials might be present in bacteria without showing
demonstrable morphological change except perhaps in the form
of increased size of the bacterial cell as a whole. For this reason
it seemed advisable to investigate this question by the method
of Forges, who rendered the heavily capsulated and inagglutinable
Friendlander bacilli agglutinable by dissolving off the capsule
with weak acid and moderate heat.
If it be true that the inagglutinability of Cohen S is due to
the f ormart;ion of a capsule or something similar, then hydrolysis
of protein of that capsule by Forges' (1905a, 1905b) method
should restore the agglutinability. With this idea in mind, we
tried the next experiment, using Rawling's serum, and carrying
out the method of Forges exactly as described by him. The
following tubes were prepared :
I. 3 cc. of each bacterial suspension plus 2 cc. of salt solution.
II. 3 cc. of each bacterial suspension plus 1 cc. of N/4 HCl
plus 1 cc. of salt solution.
VABIATIONS m TYPHOID BACILLI
315
III. 3 cc. of each bacterial suspension plus 1 cc. of N/4 HCl
plus 1 cc. of N/4 NaOH.
To 0.5 cc. of each of these mixtures graded serum dilutions
from 1 : 100 to 1 : 25,800 were added; also to a salt solution control.
Results were as follows:
•OLX^
BAcrmaiAL
•UBPSM-
BXOM
DILUTION or rawlxno'b bsrum
BAIV
CON-
TION
100
200
400
800
l.fl00
3.200
6.400
12,800
26,600
TBOL
III]
Cohen B
Cohen 8
Cohen B
Cohen 8
Cohen B
Cohen 8
+8
+8
+++
+8
+
+++
+
+8
++
+++
+ + +
+8 B slight agglutination.
In another experiment suspension I, II (without the addition
of 1 cc. of salt solution) and III (without the addition of 1 cc.
of N/4 NaOH solution) were made up. They were heated at
80^C. in a water bath for fifteen minutes, and then cooled in
cold water. To no. II, 1 cc. of salt solution and to no. Ill,
1 cc. of N/4 NaOH solution were added respectively. After
being shaken well, 0.5 cc. of each suspension was added to each
of the serum dilutions described above.
The results were as follows:
■OLV-
BACrUOAL
sinraN-
BIOV
DiLcmoir or bawlxng'b bsbux
CON-
Tiom
100
200
400
800
1,600
8,200
6,400
12,800
28,600
TROL
Cohen B
Cohen 6
Cohen B
Cohen 8
Cohen B
Cohen 8
+
+
+
+8
+8
++
+ + +
++ +
+++
316
KAN-ICHIRO MORIBHIBIA
From these 'experiments it becomes apparent that the inag-
glutinability of our serum strains is not analogous to the similar
inagglutinability of the Friedlander bacilli used by Forges in
his experiments. At any rate our experiments do not permit
us to conclude that the acquired inagglutinabiUty of our strains
is due to a capsule or to any analogous substance.
Add ogglviinaMon
In 1911 Michaelis (1911) investigated the flocculation of
bacteria by acids. His experiments were based upon the fact
that serum globulins^ casein, the so-called nucleoproteins and
other forms of protein could be shown to precipitate at very
definite optimum H-ion concentrations. Since Kraus (1897)
and Neisser and Friedemann (1904) had claimed that the agglu-
tination of bacteria depended upon the precipitation of a protein
constituent of their cell bodies, Michaelis believed that for each
species of bacteria an optimum H-ion concentration could be
found which would agglutinate them. This he indeed demon-
strated, and claimed that the typhoid bacillus especially could
be shown to agglutinate at a definite H-ion concentration suffi-
ciently characteristic to aid in the diagnosis of this organism.
A number of investigators have confirmed this. For this reason
we carried out the Michaelis technique with our broth and serum
strains, to determine whether the H-ion optimum for agglutina-
tion had been altered by growth in serum.
The solutions were made as follows :
NUKBBB
NOBKAL BODIITM HTDBATX
NOBMAX. JLCnXC AOXO
trrmRjLm waxbb
ec
CC
ec
I
0.5
0.75
8.75
II
0.5
1.0
8.5
III
0.5
1.5
8.0
IV
0.5
2.5
7.0
V
0.5
4.5
5.0
VI
0.6
8.5
1.0
VII
10.0
VII
10 cc. of 0.85 per cent salt solution
VABIATIONS IN TYPHOID BACILU
317
Both Cohen S and Cohen B cultures were suspended m sterile
distiUed water. Then 0.5 cc. of each of the above solutions and
0.5 cc. of bacterial suspension were put in small test tubes and
the results recorded after two hours incubation at 37°C.
CohenS
CohenB
C-188B
Michaelis results of ty-
phoid bacilli
Bact. coli by Michaelis
results
n
+s
+
nz
++
+
++
IV
++
++
++
+
▼1
+s
+s
▼n
vm
This experiment shows that cultivation in serum has rendered
the Cohen strain inagglutinable in an H-ion concentration which
agglutinates the normal strain. In this test Cohen S resembles
Bact. coli, but other tests (sugar fermentation) showed it to be
an absolutely typical typhoid bacillus.
Similar tests were made with an inorganic acid, as follows :
HCl agglvtination
Suspensions of both strains (Cohen S and Cohen B) were
made in sterile water. From normal hydrochloric acid solutions
in the following table were prepared by adding sterile water,
0.5 cc. of bacterial suspension, and 0.5 cc. of each acid solution
were mixed in small test tubes and incubated at 37° for two hours,
* then stood in the ice chest overnight. The results were then
noted.
The table below shows the final dilution of hydrochloric acid
in the combination of acid and bacterial suspension :
PBOPOBTZON OW ACID
WATBB
COK-
10
26
50
100
20
400
800
1.600
8.200
6.400
12300
TBOL
Cohen S
Cohen B
+++
+ + +
+ + +
+
—
—
—
318 KAN-ICHIRO MOmSHIMA
Here Cohen S is very agglutinable in the presence of hydro-
chloric acid, although it is not so in the presence of acetic acid,
as we have seen in Michaelis' test. Michaelis himself used only
acetic acid.
SUMMARY AND CONCLUSIONS
In the study described above we have endeavored to investigate
the variations which may occur in the characteristics of typical
tjrphoid bacilli in regard to their abilities to utilize carbohydrates,
and their behavior to serum antibodies under various conditions
of cultivation. Underlying oiu* plan of experimentation was the
piuTpose of determining whether variations noted by others and
described in many published accounts could properly be regarded
as mutations in the botanical sense, and, secondarily, to con-
tribute to the comprehension of the nature and the permanence
of variations from type so often noticed in freshly isolated
cultures, incidentally thereby shedding some light upon the prac-
tically difficult problems so often encountered by the bacteri-
ologist in the identification of strains isolated from the human
and animal body.
In ord^r to obtam a true picture of the fermentative character-
istics of a given species of bacterium it is clear from the foregomg
study that the inoculation of a rather small number of strains
into fluid media containing the various sugars and the recording
of acid and gas production after a few days' incubation is entirely
inadequate. A large niunber of strains must be investigated
and the period of observation extended to thirty days, if neces-
sary. Fiuiliermore, it seems advisable to regard ''fermentation"
not as the production of gas and acid or even as the production
of acid from the sugar by the bacterium, but simply as the
utilization of the sugar as a food by the bacterium. Fermen-
tation in this sense is demonstrated quite conclusively on agar
plates if characteristic daughter colonies appear on the agar
containing the sugar and no daughter colonies appear on control
plates of the same agar without the sugar; precisely those cul-
tures that yield unsatisfactory results in broth containing the
sugar are apt to give rise to a well marked development of
(
VARIATIONS IN TYPHOID BACILM 319
daughter colonies. The writer believes that this method deserves
a much more extended use in bacteriology than it has hitherto
received. It seems likely that one could employ it to determine
whether xother substances besides sugars, for example, certain
amino-acids, are utilized by the bacterium in question as a food,
and in this way obtain a more accurate knowledge of the metabo-
lism of the orga&i^m and possibly important diagnostic distinc-
tions also.
By investigating a large number of strains of BacL typhosum,
using broth fluid and solid media and extending the period of
observation over several weeks time it was observed that the
behavior of many strains toward certain sugars varied widely
from that of other strains. The slow fermenters of xylose
resemble the mutations of the higher plants first described by
de Vries, more closely than some of the other variants considered
in this paper because they retain their characteristics quite
constantly (for several years at least), so long as they are not
grown in media containing xylose; all such strains investigated
by us, with one exception, could be trained by long continued
cultivation in xylose-media to produce acid in xylose broth in
twenty-four hours like the typical BacL typhosum. Furthermore,
all of these slow fermenters, including the one that never produced
acid in xylose-broth for us, showed daughter colonies on xylose
agar; hence we were aware of the fact that these strains could
utilize xylose as a food-stuff long before this had become evident
from the observation of the xylose-broth tubes.
These observations would seem to indicate that even in the
slowest xylose fermenters the xylose utilizing power is potentially
rc$tained as a latent characteristic. This would prevent our
correctly applying to such cultures the term "mutation" in the
sense of de Vries. Working with bacteria we are enabled to
observe in a short time a sequence of generations far beyond
anything that can be observed with higher plants and our work
suggests, though of course in an entirely inconclusive way, that
at least some of the ''mutations" described by botanists may
represent, in fact, a suppression of characteristics which remain
latent and might easily become apparent again could a sufficient
320 KAN-ICHIRO MORISHIMA
number of generations be subjected to an environment in which
this characteristic could again become useful.
The inoculation of solid media proved that all of our strains
of Bad. iyphosum utilize both arabinose and dulcitol for their
nutrition. In jQuid medium nearly half of the strains produced
acid in dulcitol in from five to twenty days while only a small
percentage showed acid production from arabinose. In striking
contrast to the behavior of the typhoid strains in xylose broth,
the strains that produced acid in arabinose or dulcitol in one
test often failed to produce acid when the test was repeated under
similar conditions.
All of our typhoid strains gave rise to daughter colonies on
rhamnose agar, but none were observed to produce acid in
rhamnose broth.
Our cultures showed no daughter colonies on raflSnose agar
and did not produce acid in raffinose broth. It is thus apparent
that instead of stating that a given species of bacterium ferments
such and such sugars, it should be said; that the organism in
question can utilize such and such sugars as a food; that the
organism produces acid in twenty-four hours in certain of these
sugars; that a majority of the strains produce acid after several
days in such and such sugars; etc., etc. Having obtained this
information concerning certain related species of bacteria it
should usually be easy to select those sugars which would yield
the most reliable information for the differentiation of the species.
Thus, Ejumwiede (1918), and quite recently Jordan also, have
recommended acid production in rhamnose broth as the most
fimdamental method of differentiating the paratyphoids from
Bad. typhoaum. We agree that this is a good practical meiivan
for the differentiation of these species but we should betr iin
mind that Bad. typhosum, although it does not show acid pro-
duction in rhanmose broth, is nevertheless able to utilize this
sugar as a food.
Considerable discussion has arisen concerning the question
whether certain of the variations from the normal type mentioned
in this paper represent true mutations in the sense of de Vries.
The writer beUeves that this term, which defined changes of a
VABIATIONS IN T7FHOID BACILLI 321
definite character occurring in hi^er plants should not be
introduced into bacteriology; for the bacteriologist, who studies
his species not only from the morphological point of view, but
also with regard to biochemical and immunological reactions,
and who observes not a few generations only, but himdreds
and thousands of generations, would almost surely have to modify
the conception of the term in such a manner as to cause confusion
to the botanist. It, therefore, seems advisable to leave the term
mutation to the botanists and, for the present at least, to speak
of atypical varieties of bacteria or simply of variants.
Typhoid bacilli grown upon normal serum do not become
inagglutinable. Cultivated continuously upon specific immime
senun they at first become inagglutinable, but if such cultivation
is persisted in for two weeks longer, eventually these strains
again become agglutinable. In some cases this return to normal
agglutinability does not occur until the seventy-second day.
This, however, is exceptional. It is important to notice that,
whereas in other e^eriments the normal characteristics had
developed, in this case a return to normal reaction with senun
was brought about in spite of a continuous subjection to the
unusual environment.
Inagglutinability of the typhoid bacillus is accompanied by
inability to absorb agglutinin. There is no difference whatever
in these relations between the xylose slow and xylose rapid
fermenters. Our experiments do not indicate that capsular
material is concerned in the inagglutinability. Treatment by
the Forges method does not render the inagglutinable strains
agglutinable.
Acid agglutination experiments by the method of Michaelis
showed that the inagglutinable serum strain reacted negatively
in the increasing concentrations of acetic acid, being in this
way sitnilar to colon bacilli, whereas the same strain cultivated
in broth reacted with the add typically as did Michaelis typhoid
cultures. In other words, the inagglutinable strains showed a
changed reaction in regard to hydrogen ion concentration of the
environment.
322 KAN-ICHIRO MORISHIMA
Finally, we believe that since all the alterations brou^t about
by artificial environment in the typhoid* bacillus were rapidly
lost when the organisms were returned to the environments pre-
vailing under the usual cultural conditions and in the case of the
inagglutinable strains, even in the course of persistent abnormal
environment, the changes observed by others as well as by us
should properly be regarded as variants and cannot be spok^
of with accuracy as mutations in the sense of de Vries.
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Krumwiedb, Cohn and Valentine 1918 Jour, of Med. Res., 88, 89.
EuwABARA, Ch. 1907 Saikingakuzassi, No. 143.
KuwABARA, Ch. 1909 Cent. f. Bakt. Ref. 1 Abt. 42, 135.
LuERSSEN AND DiTTHORN 1912 Cent. f. Bakt., 1 Abt. 68, 47.
Mandelbaum, M. 1912 Cent. f. Bakt. 1 Abt. Grig. 68» 46.
Massini 1907 Arch. f. Hyg. 61, 251.
McNauoht, J. G. 1905 Jour, of Path, and Bact., 10, 380.
MiCHABUB, Lbonor 1911 Deut. med. Woch., 969.
Moon, V. H. 1911 Jour, of Inf. Dis., 8, 463.
MoRismMA, K., AND Teaoue, Gscar 1917 Jour, of Inf. Dis., 21, 146.
Mt^LLER, Reiner 1908 Deut. Med. Woch., 1961.
MttLLBR, Reiner 1911 Cent, f . Bakt. 1 Abt. Grig. 68, 97.
MttLLER, Paul Th. 1903 MOnch. med. Woch, 1, 56.
Neibber, I. M. 1906 Cent. f. Bakt. 1 Abt. Ref. 88, 98.
VARIATIONS IN TYPHOID BACILLI 323
Neisbeb and Fribdemann 1904 Mtlnch. med. Woch., 61, 465 and 827.
Park and Williams 1917 Pathogenic MicroorganismB, 6th Ed., 208.
Park and Wiluams 1920 Pathogenic Microdrganisms, 7th Ed., 55.
Peckham, A. W. 1897 Jour, of Exper. Med., 2, 549.
Penfold, W. J. 1910 a Brit. Med. Jour., 2, 1672.
Penfold, W. J. 1910 b Jour, of Path, and Bact., li, 406.
Penfold, W. J. 1911 Jour, of Hyg., 11, 329.
Penfold, W. J. 1914 Brit. Med. Jour., 2, 710.
PoROES, Otto 1905 a Wien. klin. Woch., 691.
PoBGBS, Otto 1905 b Zeit. f . Exp. Path. u. Ther.
PoRGES AND Prantschoff 1906 Cent. f. Bakt., 41.
Pringsheim, Hans 1911 Med. Klinik, 1, 144
Russowici 1908 MOnch. med. Woch., 56, 2507.
Sacqubpee 1901 Ann. de I'lnst. Pasteur, 16, 261.
Saisawa, Kohzoh 1913 Zeit. f. Hyg., 74, 61.
Sawyer, Wilbur A. 1912 Jour. A. M. A., 68, 1336.
Schattbnfroh, a., and Grassbbrger, R. 1900 Arch. f. Hyg.
ScHBLLER, Robert 1908 Cent, f . Bakt. 46, 385.
Schmidt 1903 Wien. klin. Woch., 873.
TwoRT, F. W. 1907 Proc. of Royal Soc. of London, Ser. B., 79, 829.
Walker, Ainlet and Mxtrrat 1904 Brit. Med. Jour., 2, 16.
Wilson, W. James 1902 Brit. Med. Jour., 12, 1910.
WiNSLOW, KuGLBR AND RoTHBERG 1919 Jour. Bact., 4, 428.
Zinsser, Hans 1918 Infection and Resistance, 2 Ed., Chap. 9.
SOLID CULTURE MEDIA WITH A WIDE RANGE OF
HYDROGEN OR HYDROXYL ION
CONCENTRATION
FREDERICK A. WOLF and I. V. SHUNK
From the Botanical Laboratory , North Carolina Experiment Station, West Raleigh,
North Carolina
Received for publication October 11, 1920
A considerable number of investigations, made during the
past few years, have extended our knowledge of the profound
influence exerted by acids and alkalis upon the growth of micro-
organisms. This is especially true in the case of such fimgi and
bacteria as lend themselves readily to cultivation on artificial
media. Investigations have also clarified many problems related
to these media themselves, such as the influence of acids and
alkalis on colloidal hydration and jellification, the buffer action
of proteins and salts, the devising of improved colorimetric and
electrometric technic for the measurement of hydrogen and
hydroxyl ion concentration, etc. The point covered in the
present study, which grew out of an attempt to determine the
limit of tolerance of certain organisms to acid and alkali on
solid media, does not api>ear to have been brought out in any
foregoing investigation. In previous studies use has been made
of liquid media for very tolerant organisms, even for forms
which are known to thrive best on solid media, since it has been
impossible to make agar or gelatin with high pH values solid.
It is the present purpose, therefore, to show that acids and alkalis
need not materially modify the physical properties of agar and
gelatin media within, and even far beyond, the limits of tolerance
of any living organism.
METHODS
The media were prepared by adding either 1 or 2 per cent
commercial agar or 10 or 15 per cent bacto-gelatin to a bouillon
consisting of 0.3 per cent Liebig's beef extract, 1 per cent Armour's
326
}
326 FBEDERICK A. WOLF AND I. Y. 8HX7NK
peptone and 0.5 per cent sodium chlorid. They were then heated
in an autoclave, flasked, and sterilized, for fifteen minutes at
15 poimds pressure in the case of agar, and 10 pounds pressure
in the case of gelatin. No attempt was made to adjust the
reaction of the media to neutrality prior to sterilization. The
acid used was hydrochloric, with a specific gravity of 1.20 or
it possessed an HCl concentration of 39.11 per cent. The
sodium hydroxid had a specific gravity of 1.226 or an NaOH
concentration of approximately 20 per cent. Strong acid and
alkali were employed to eliminate the factor of dilution of the
media. Upon removal from the autoclave the agar was cooled
to about 50'C. and the gelatin to about 40''C. before the addition
of appropriate quantities of acid or alkali, and were maintained
at these temperatures while 10 cc. portions were withdrawn
with a pipette and put into test tubes. The acid or alkali was
added to these 10 cc. portions with a 1 cc. pipette graduated in
tenths. After the addition of the acid or alkali the tubes were
well agitated and were further cooled with the results indicated
in the tabulations which follow.
EXPERIMENTAL
Only those proportions of agar or gelatin which are conmionlj
employed in making culture media were used in this study but
they indicate, as would be anticipated, that the jellifying power
is modified by the proportion of colloidal material added. The
results with 1 and 2 per cent agar are shown in table 1.
It will be noted that the limits of solidification of 1 per cent
agar are approximately 5.11 per cent acid and 0.39 per cent
alkali whereas 2 per cent agar does not lose its jellifying power
xmtil 6.51 per cent acid or 0.58 per cent alkali has been added.
A better appreciation of the degree of acidity and alkalinity
of these limits can be gained when they are compared with pH
values determined by the colorimetric method of Clark and Lubs
(1917). It was found that the addition of 0.1 cc. of HCl to
10 cc. of agar gave a concentration of about pH 1.4 and 0.03 cc.
NaOH a concentration of about pH 9.2. In reaching the limits
CULTUBE MEDIA WITH WIDE RANGE OF HYDROGEN
327
in 2 per cent agar it will be seen that 20 times this volume of acid
and 9 times this volume of alkali were employed. Manifestly
these limits are only approximate and could be more accurately
determined by improved technic. They are, however, far beyond
the limits of tolerance of microorganisms and are intended only to
show that hydrogen or hydroxyl ion concentration need not be
limiting factors in the preparation of solid agar media.
TABLE 1
Effect of acid and alkali on solidification of agar
1 PKB CCNT AOAB
2 PBB CBNT AOAB
Agar
HCl
NaOH
Physical state,
20'C.
Agar
HCl
NaOH
Phyucal state,
20-C.
cc.
ee.
per
cent
ee.
per
eeni
•
cc.
10
10
ee.
2.0
1.7
per
cent
6.51
5.68
ee.
per
cent
Semisolid
Solid
10
1.6
5.11
Semisolid
10
1.5
5.11
Solid
10
1.2
4.19
Solid
10
1.2
4.19
Solid
10
1.0
3.55
Solid
10
1.0
3.55
Solid
10
0.7
2.65
. Solid
10
0.7
2.55
Solid
10
0.5
1.86
Solid
10
0.5
1.86
Solid
10
0.3
1.14
Solid
10
0.3
1.14
Solid
10
0.1
0.38
Solid
10
0.1
0.38
Solid
10
0.1
0.19
Solid
10
0.1
0.19
Solid
10
0.2
0.39
Semisolid
10
0.2
0.39
Solid
10
0.3
0.58
Liquid
10
0.3
0.58
Semisolid
All of the agar media in these series appear to be able to remain
solid for an indefinite period when they are maintained at room
temperature. If, however, they are autoclaved and then cooled
all of the acid media were found to remain liquid, whereas the
tubes of 1 per cent agar with 0.1 cc. NaOH and 2 per cent agar
with 0.1 and 0.2 cc. NaOH became solid again.
Considerably larger amoimts of acid or alkali must be added
to 10 and 15 per cent gelatin to destroy the jellifying power as
shown in table 2.
In the case of 10 per cent gelatin the limits are seen to be
about 9.02 per cent HCl and between 3.33 and 4 per cent NaOH,
and of 15 per cent gelatin between 9.02 and 10.15 per cent HCl
JOUBKAL or BACrBBXQLOGT, VOL. TI, NO. 3
328
FREDERICK A. WOLF AND I. V. 8HXJNK
and about 4 per cent NaOH. When these media were examined
after having been maintained in an ice chest at about WC. for
twelve hours, all of those to which more than 1 cc. of NaOH
had been added were foimd to have become liquid, and a heavy
whitish precipitate had formed. All of the tubes to which HCl
had been added were still solid, however. All of the tubes
containing media which had remained solid were placed id
boiling water until the media had liquified whereupon they
TABLE 2
Effect of add and alkali on solidification of gelatin
10 PBB CXVT GKLATIK
16 PXB CBHT OXLA,TIir
GelA-
tin
HCl
NaOH
PhyBioal state
GeU-
tin
HCl
NaOH
Phyrieal state
7.6X3,
cc.
ce.
per
cent
ce.
per
eerU
ee.
10
ce.
3.5
per
cent
10.15
ee.
per
cent
Liquid
10
3.0
9.02
Semisolid
10
3.0
9.02
Semisolid
10
2.5
7.82
Solid
10
2.5
7.82
Solid
10
2.0
6.51
Solid
10
2.0
6.51
Solid
10
1.7
5.68
Solid
10
1.7
5.68
Solid
10
1.5
5.11
Solid
10
1.5
5.11
Solid
10
1.2
4.19
Solid
. 10
1.2
4.19
Solid
10
1.0
3.55
Solid
10
1.0
3.55
Solid
10
0.5
1.86
Solid
10
0.5
1.86
Solid
10
0.5
0.95
Solid
10
0.5
0.95
Solid
10
1.0
1.82
Solid
10
1.0
1.82
Solid
10
1.2
2.14
Solid
10
1.2
2.14
Solid
10
1.5
2.61
Solid
10
1.5
2.61
Solid
10
1.7
2.90
Solid
10
1.7
2.90
Solid
10
2.0
3.33
Solid
10
2.0
3.33
SoUd
10
2.5
4.00
Liquid
10
2.5
4.00
Semisolid
were again cooled to T.S'^C. The alkaline gelatin again solidified,
but 1.5 cc. of HCl in 10 per cent gelatin and 1.7 cc. in 15 per
cent gelatin were now the limits of the jellifying power.
DISCUSSION
Manifestly, in the case of both agar and gelatin, strong acid
or alkali in the presence of high temperatures is capable of
destroying the jellifying power. Everyone who has made culture
CULTURE MEDIA WITH WIDE RANGE OF HYDROGEN 329
media according to accepted methods, i.e., sterilized them after
the adjustment of reaction, has found that an acidity of 2 to
2.5 per cent normal HCl or a pH concentration of approximately
4 to 3.5 is the limit of solidification of agar. Alkalis in related
proportions in the presence of heat have been found to exert
a similar action on the jellifying power of agar. Fellers (1917),
however, found that this range of jellifying power for 2 per cent
agar could be extended to 5 per cent normal HCl or 5 per cent
KOH if the acid or alkali were added while the agar was boiling
hot and it was not subsequently sterilized. These highly acid
or alkaline media were furthermore employed by him (1916)
in studies on soil flora, since appropriate quantities could be
transferred by means of a sterile pipette to sterile Petri dishes.
When one permits the media to cool before adding the acid or
alkali as was done in our studies, and as is indicated in Fellers'
work, the range of solidification may be extended very much
farther. The application of the principles involved herein are
believed to make it possible both to simplify the making of
me^ and to improve methods for investigation on the influence
of hydrogen ion concentration on microorganisms. Reference to
two recent papers one by Webb (1919) on the influence of reaction
on the germination of fimgous spores and the other by Fred and
Davenport (1918) on the growth of nitrogen assimilating bacteria,
will illustrate the possibilities which may come in similar studies
from the use of very acid or very alkaline solid media.
In routine work it will be f oxmd to be advantageous to flask
and sterilize the media in 200 cc. quantities for the reason that
the addition of 1 or 2 drops of strong acid or alkali to this quantity
will bring about a change in concentration of about pH 0.2.
When acid is added to agar in flasks at 50** to 60°C. it may be
thoroughly agitated by whirling, 10 cc. portions may be removed
for comparison in reaction with the color standards of Clark and
Lubs (1917), and when the usual precautions against contamina-
tion are observed the material in the flasks may be kept sterile,
while the adjustment to the desired pH concentration is being
made. The agar may then, before it has had time to solidify,
be poured into sterile test tubes or sterile Petri dishes, where-
330 FREDERICK A. WOLF AND I. Y. SHUNK
upon it is ready for use. The danger of contamination from
this procedure, as judged by experience in making several thou-
sand tubes of media, is no greater than when the tubes are steri-
lized after the media has been placed in them, as is usually done.
In summary, this procedure removes the necessity of sterilization
after adjustment of reaction, eliminates the chances of change of
reaction or of other chemical changes which may be hastened by
a rise in temperatwe, and does not, within a wide range, destroy
the jellifying powers of the agar or gelatin.
CONCLUSION
Agar or gelatin media, if cooled before being made acid or
alkaline, will jellify at limits far beyond pH concentrations
tolerated by microorganisms. They may be manipulated so as
to avoid contamination during adjustment of reaction and need
not be subsequently sterilized.
REFERENCES
Glabk, W. M. , Ain> LiTBB, H. A. 1917 The colorimetric determination of hydro-
gen ion concentration and its applications in bacteriology. Jour.
Bact., 2, 1-34, 109-136, 191-236, f. 1-8.
Fellers, C. D. 1916 Some bacteriological studies on agar. Soil Sci., 2, 2S&-
290.
Fellebs, C. D. 1917 The analysis, purification, and some chemical properties
of agar-agar. Jour. Indus. Eng. Chem., 8, 1128-1132.
Fred, E. B., and Davenport, Attdret 1918 Influence of reaction on nitrogen
assimilating bacteria. Jour. Agr. Res., 14, 317-336.
Webb, R. W. 1919 Germination of the spores of certain fungi in relation to
hydrogen ion concentration. Ann. Mo. Bot. Garden, 6, 201-222.
STUDIES ON AZOTOBACTER CHROOCOCCUM BEIJ.
AUGUSTO BONAZZI
Contribution from the Ohio Agricultural Experiment Station, Wooeter, Ohio,
Laboratory of Soil Biology
Received for publication October 15, 1920
I. GENERAL
Inirodudion
The study of the metabolism of Azotobacter has been gen-
erally approached from the standpoint of the rdle of this organ-
ism in the nitrogen cycle in Nature, but the fact that the ability
to fix free nitrogen is regulated by the presence or absence of
combined nitrogen in the medium has not been given serious
attention although it is made plain in the works to be cited.
Bejierink and Van Delden (1902) have shown that Azotohact&r
chroococcum possesses the power to transform nitrates directly
into ammonia and lipman (1903), Stoklasa (1908), Stranak
(1909) and Heinze (1906) found that small quantities of nitrates
'' atimvlcUed" nitrogen fixation by this organism. If the property
of nitrogen fixation were a function of the normal life cycle, it
seems strange that, although of vital importance, it should be
overcome with such facility. In this connection the data pre-
sented by Hills (1918) are most instructive. The accompansdng
table is a recalculation of the data given by him on pages 200-
203 of his contribution, and is chosen as it is the only one given
which was obtained by the use of a synthetic medimn.
From this compilation we see that in presence of abundant
stores of nitric nitrogen Azotobacter does not fix atmospheric
nitrogen but assimilates the nitrogen of the nitrates. A close
study of the original data shows that in the presence of ammo-
nium nitrate the organism has a preference for the nitrate radicle
leaving the ammonium radicle untouched.
331
332
AUGXTSTO BONAZZI
The most important feature of the recalculated data, and one
that the author apparently overlooked, is the one presented in
the last column of table 1. A very appreciable "loss^^ of nitro-
gen takes place from the cultures, either as free nitrogen or as a
volatile nitrogenous compound. It is assumed that the cultures
used by Hills were pure.
Greaves (1918) in his recent review of this work seems not to
consider this important phase of the metabolism of Azotobacter.
TABLE 1
Nitrogen hcdaneea in ike cultures of HiUs
TRMATMXXn OW
aoLunon
TOTAL xnBOonr
PHACUOUWTKB ffOB,
Inooukted
Cheek
PBOBA.BLT von BT
n A<7F«Vf AT| ArVfAW
^ {
NaNO,
NH4N0«
NaNO,
NH4NO,
105.20
162.12
135.60
102.85
164.05
206.75
164.d5
206.75
50.75
44.63
20.86
13.00
After this very brief survey of the data in question it may be
well to recall a statement which appeared in a previous communi-
cation from this laboratory (1915) to the effect that A. chro-
ococcum may be a fixer of atmospheric nitrogen only under such
conditions as we call ''normal/' i.e., in absence of fixed nitrogen
and a denitrifier when such conditions are changed, i.e., when
there is a possibility for it to consume nitrate under naturally
normal conditions. In our present study of the literature we
have excluded purely agronomic investigations and have con-
sidered only studies which have been made under conditions of
control such as to give results of fundamental importance.
Historical
A simple study of the relation of the carbon consumed to the
nitrogen fixed has only a limited value, and this is especially
true when we consider the great variations in the nitrogen fixing
power of the same organism imder different conditions. The
quality of the carbohydrate utilized in the experiment and its
BTUDIES ON AZOTOBACTER CHBOOCOCCT7M BEU. 333
relation to the fixation of nitrogen have received considerable
attention but it should be stated nevertheless that the ratio
C:N, as often reported in the literature, has no absolute value
since the determination of the carbon actually utilized has
not been attempted, a complete consumption of all the carbo-
hydrate originally present having been assumed.
Furthermore it must be stated that by following the practice
of allowing all the carbohydrate to disappear from a solution
the cultmres are submitted to a negative phase, one of actual
starvation which, as will be seen later vitiates the results of the
experiments.
The excellent work of Koch and Seydel (1912) on the influence
of the concentration of carbohydrate is typical of the results to
be obtained when the concentration of sugar and time of incu*
bation are made elements in an experiment. In fact from theii*
work it is evident that each period of incubation has an optimum
concentration of sugar a finding that makes it impossible to draw
definite conclusions from data obtamed with a given sugar con-
centration and an arbitrary niunber of days of incubation.
Stoklasa (1908), using glucose as a source of carbon, concludes
that the products of carbohydrate attack by Azotobacter are:
ethyl alcohol, formic acid, acetic acid, butjrric acid (only once in
anaerobic conditions), lactic acid, carbon dioxid and hydrogen.
From his data it would appear as if the glucose actually incor-
porated by the cells during the period of his experiments should
be represented by
granu
Glucose actually consumed 16.8000
Glucose fouiK^ in byproducts 9.3790
Glucose theoretically in cells 6.5110
But Stoklasa sums up his observations by stating that he can-
not account for this quantity of 6.5110 grams of glucose and that
probably not all the by-products were determined. A second
possible reason for such unaccounted for glucose he assumes to
be f oimd in the inaccuracy of the methods for the determination
of the by-products (volatile and non-volatile acids).
334 AUGUSTO BONAZZI
To reconcile this work with the statements of Omeliansky and
Sewerowa (1911) is impossible if we assume both groups of
workers to be working with pure cultures of the organism in
question. Although statements as to the purity of his cultures
were made by Stoklasa, the fact that hydrogen in the free state
was found to be generated in appreciable quantities, as well as
butyric acid, in some cases, would tend to make this purity
questionable.
If now we consider in this connection the work of Krzmieniew-
sky (1908) we have a series of most interesting data that bring
out two very striking features: 1, complete lack of hydrogen
production and, 2, striking difference in the COs :0s ratios result-
ing from the utilization of glucose and mannitol. One feature
of this work which deserves special attention is that the ratio of
COs formed to nitrogen fixed is not constant. Expressed in
other words there does not exist a constant C :N ratio for Azoto-
bacter. The nitrogen fixation from the atmosphere is such that
it cannot be considered as a normal and essential function,
necessary to the cell economy of the organism, but rather as an
incidental or secondary factor in the cell metabolism. As an
addendum to the main bulk of his work Krzmieniewsky men-
tions a series of experiments which fail to corroborate the find-
ings of Stoklasa, with regard to the formation of by-products,
and cast thereby additional doubt on the purity of the cultures
of the latter investigator. That this difference in the metab-
olism (production of organic acids and alcohols) may not be due
to differences in the organisms studied or, necessarily, to impuri-
ties is shown by some of the data presented by Maz4 (1902).
That an organism such as Eurotiopsis gayonvi is capable of
changing its physiology and the nature of the by-products of its
life activities (imder anaerobic conditions performing only the
process of intramolecular respiration) would tend to convince
us that Stoklasa might not have been working with impure cul-
tures but may rather have been growing his cultures under con-
ditions of anaerobiosis. That such a process of anaerobiosis is
possible in Azotobacter may be postulated when we consider the
work of Maz6 on the assimilation of glycerol, lactic acid and
aldehyde by Eurotiopsis.
STUDIES ON AZOTOBACTBR CHROOCOCCUM BEU. 335
Nevertheless, although lactic acid and alcohol could be
assumed as by-products of an abnormal physiology of Azoto-
bacter, the production of hydrogen and butyric acid suggests a
contaminating form.^
The fact that Azotobacter gave a ratio C02:0s of about unity
in Krzmieniewsky's work does not in itself indicate that all the
carbohydrate consiuned is utilized in a process of combustion.
In fact, it is unfortxmate that with such a careful study of the
gaseous exchange in their cultures these authors were not in a
position to present data showmg the actual disappearance of the
carbon source from the solutions.
If we consider the carbon balances in the mathematical terms
introduced by Duclaux (1900) we obtain the following equation.
S = m.L + n.l.t (1)
where S is the quantity of sugar consumed, L the weight of the
cells at the end of the incubation period, I that quantity of cel-
lular substance that constitutes the average throughout the
period of experiment, m the quantity of sugar actually to be
found in the mass of one imit of cellular substance, n that quan-
tity of sugar necessary for the maintenance of one unit of
cellular substance during the imit of time L
OmeUansky and Sieber after a study of the composition of the
cells of Azotobacter (1913) grown on agar concluded that cells of
Azotobacter contained a relatively small quantity of protein
(about 13 per cent), their greater mass being made up of nitro-
gen-free substances. It is possible that the heavy "schlime-
schicht" that surrounds the cells during the early stages of
development should not be forgotten in this connection as also
the peculiar granulations to be found in the cells of this organ-
ism (Bonazzi, 1915) and which play a r61e in their life cycle that
is not as yet completely imderstood. It is possible that such
structiures are largely made up of that sugar carbon which
has been denominated m in the above equation. But as will be
^ Krzmieniewsky admits of the possibility that the organism which Stoklasa
was studying was not Azotobacter.
X
336
ATJGUSTO BONAZZI
seen later these same structures are utilized in future life and
should therefore be considered again in the calculation of n,that
quantity of sugar which goes to the maintenance of the oeH^
The above analysis of the literature leads us to the following
considerations : a) the C :N ratio of Azotobacter is an inconstant
valuC; b) the metabolism of this organism is not as yet. well
understood, c) the nitrogen fixing capacity of this organism
seems to be a function of secondary importance in the cell
economy.
n. EXPERIMENTAL
Carbon relations
C0s:0s ratio and sugar consumption
Experiment 44- A large flat-bottomed Fembach flask was
fitted with the attachment shown in figure 1.
Fig. 1. o, culture flask; 6, d, e, gas collecting chain; c, mercury valve;/, culture
solution; x, paraflin and plaster of paris seal fitted over the ground glass stoppers
to avoid possible gas leaks.
The total volume of the apparatus was 3290 cc. and since
100 cc. of solution were used, the total volume of air over the
solution was 3190 cc. The solution used was of the following
composition :
Deep well water 500.00 cc.
K1HPO4 0.10 gram
Glucose 10.00 grams
* Krainsky obtains curves on the COs production of cultures of Azotobacter
but unfortunately gives no data on the actual sugar consumption.
STUDIES ON AZOTOBACTER CHROOCOCCUM BEU,
337
One hundred cubic centimeters of this solution were placed in
the flask together with 0.50 gram of precipitated CaCOs. After
sterilization and inoculation with a pure culture of Azotohacter
chroococcum the whole apparatus was sealed and incubated at
25^C. for forty-eight days. A gas analysis at the start of the
incubation period and at the end gave the results shown in
table 2.
TABLE 2
Gaa changes in ctdiure of Atotohacter chroococcum
coaffOsmoH or aim
•
OA0
At start
At the end
TOTAL OAB
BALANOn
Per cent
Actual
Percent
Actual
CX>j
0.00
20.30
0.00
oe.
0.00
647.60
0.00
9.70
11.33
0.00
309.40
361.40
0.00
ee.
+309.4
-286.2
0,
Hi
0.0
Calculating the ratio C0s:0a we obtain the value 1.08 which
closely approximates the value 1.02 obtained by Krzmieniewsky
in his work with glucose. But under such high partial pressure
of COs the solution in the flask can contain appreciable quanti-
ties of this gas in solution. In fact by titration of the solution
with NasCOs and H2SO4 it was found to contain 50.70 mgm. of
carbon dioxid. Gravimetrically then, the quantity of CO2 in
the air would be 607.80 mgm., and that in solution 50.70 mgm.,
giving a total quantity of 658.50 mgm. of carbon dioxid in the
system. The oxjrgen consumption was of 286.20 cc. correspond-
ing to 408.80 mgm. of Os. A sugar analysis showed the following
changes in the solution:
Uninoculated 1S40.0 mgm. GcHuOc
Inoculated 41.2 mgm. C«HisOt
Total Bugar consumed 1798.8 mgm.
Assuming the oxygen to be utilized in the combustion of the
sugar according to the following equation (equation 2) which
338
AUOTJSTO BONAZZI
represents only the final changes, we are in a position to estimate
the quantity of COt which should have been formed in the
process (table 3).
CeHwOe + 6O2 -♦ 6 CO, + 6 H2O (2)
The final result of this experiment is therefore to show that
more carbon dioxid is formed and more sugar consumed than
can be accounted for by the amount of oxygen consumed.
The solution in the particular flask was the seat of vigorous
development, beginning with the formation of a ring at the point
of air-glass-solution contact, slowly clouding the whole solution
and later sinking to the bottom of the flask in the form of a
heavy deposit exhibiting the gray-brown pigmentation char-
acteristic of Azotobacter.
TABLE 8
Gm balances in cultures of Azotobacter
ClHuOf COMBUICBD
Oi vnusBD
COirOBMKS
Actual
mifm.
1708.8
383.2
ttlQtli,
408.8
408.8
mom.
658.5
Calculated
562.1
Differences
+1416.6
0.0
+96.4
The quantity of sugar unaccounted for may well have been
found in the cell body and secretions had an effort been made to
account for the whole. Since this was not done we are only
justified in assuming such a possibility. That some secondary
actions do take place in a culture of Azotobacter is shown by the
presence of 96.4 mgm. COs in excess of the theoretical amount.
We may safely assume at present that this quantity of carbon
dioxid is derived from a process of intramolecular respiration.
A proof of this may be found in a later part of this paper, unda-
the heading of Autophagy. This assumption is also in agree-
ment with the equation of Duclaux for aerobic organisms, and is
substantiated by the following experiment.
Experiment Jfi. A large Fembach flask fitted with the attach-
ments shown in figure 2, received 100 cc. of a solution of the
composition shown below:
STUDIES ON AZOTOBACTEB CHROOGOCCT7M BEU.
339
Deep well water 250.00 co.
KiHPO* 0 . 05 gram
Glucose 6.00 grams
Ca(NOi), + 4H,0 0.316 gram
Calcium carbonate was added in the quantity of 0.5 gram.
The total volume of the apparatus was of 2666 cc. and the
addition of the solution left 2566 cc. of air space. After sterili-
zation and inoculation with a pure culture of Azotohader chro-
Fio. 2. a, culture flask ; 6, d, e, gas collecting chain ; e, mercury yalve ; x, paraffin
and plaster of paria seals over ground glass joints.
TABLE 4
Gas changes in culture of Atotobacier chroococcum
OOMTOUnON OW AZB
QAM
Before
After
CBAMOKSIN
TOTAL OAS
Percent
Actual
Percent
Actual
COl
0.13
20.21
ee.
3.33
518.50
20.70
1.02
ec.
531.20
26.17
CC.
+527.87
Ot
-492.33
Ht
ococcum the apparatus was incubated at about 25^0. for fifty-
two days, after which period a gas analysis was made. Com-
paring the results obtained at the end to the values at the start
of the experiment we may calculate the gas exchanges in the
culture as shown in table 4.
340
AT7GUBT0 BONAZZI
Calculating the C0j:02 ratio we obtain the value 1.07. Here
again a very close approach is seen to the value obtained by
Krzmieniewsky when glucose was used as a source of carbon.
Again here as in the previous experiment the carbon dioxid
dissolved in solution was determined and foimd to be 44.36
mgm. and the quantity of this gas in the atmosphere 1037.0
mgm. The total weight of the gas formed then would be 1081.4
mgm. while a total quantity of 703.3 mgm. of oxygen was con-
sumed. A determination of the sugar concerned in the action
follows:
Uninoculated 1701.0 mgm. CeHnOt
Inoculated 672.8 mgm. CcHisOt
Total sugar consumed 1128.2 mgm.
If we assume that the consumed oxygen was utilized wholly in
the process of sugar combustion we obtain the balances shown
in table 5.
TABLES
Oaa balances in culturea of Atoiobacier
CiHiflOi oomuiiBD
OsVTXLinD
COtroBfSB
Actual
1128.2
659.4
703.3
703.3
1081.4
Calculated
967.2
•
Di£Ference8
+468.8
0.00
+114.2
Here again we see indications of an intramolecular respiration
taking place with a consumption of sugar above the theoretical.'
Comparing now the data from the two experiments mentioned
above we have table 6.
It seems evident therefore that the cells of Azotobacter beades
retaining abundant stores of the carbohydrate with which they
' A third experiment of the series, in which the COtiOt ratio has been deter-
mined, gave a value of 1.09 for the respiratory exchange, a value in very close
agreement to the others here reported. A summary of the COtiOt ratios foUows:
Experiment 44 1.08
Experiment 46 1.07
Experiment 78 1.00
Value of Krzmieniewsky 1 .02
^
STUDIES ON AZOTOBAGTEB CHBOOGOGCUH BEU. 341
are placed in contact secrete or produce in the surrounding
medium compounds, the nature of which has not been deter-
mined. Before attempting to study these compoxmds we shall
enter mto a closer analysis of the above experiments. Expressing
the quantity of unaccounted for sugar in terms of percentage
of the amoimt of sugar actually disappeared from solution we
obtain table 7.
TABLES
Summary of tables S and 6; values obtained in excess of theoretical
None . .
Nitrate
CdSuOt
+1415.6
+468.8
COi
+96.4
+114.2
TABLE 7
Sugar unaccounted for as per cent of the sugar which disappeared
TBBATMSMT
VALXm
None . • .
.•
78,71
Nitrate
41.66
It is obvious that no relation whatever exists between the
sugar unaccoimted for and the COs formed in excess of the
theoretical, and from table 7 we gather that the addition of
nitrogen in the form of Ca (NOs)s has induced a profoxmd change
in the physiology of Azotobacter. That the nitrogen is actually
consumed during the process of growth could be assumed from
the published works of other authors, but to obtain more specific
results we may summarize the data obtained on the above men-
tioned cultures (table 8).
The transformation of nearly 10 mgm. of nitric nitrogen into
organic nitrogen (which was probably in part organized) is
directly connected with the carbohydrate consumption and with
the stores of carbon in the cell body and by-products. If such
soluble and insoluble material were actually formed it should be
possible, by stopping fermentation in its early stages or by an
oxygen hunger, to obtain a carbon balance showing a greater
342
AUGUSTO BONAZZI
disappearance of sugar than can be accounted for by the actual
oxygen consumption; and the carbon dioxid production should
be correspondingly diminished. That this is what actually
happens is shown by the following experiment.
TABLES
Nitrogen balances of Azotobacter
CDl/TUBB
■
No nitrate
Nitrate
NHi
NiOi
Orcanio
Total
NH«
N»Os
Oicanie
Total
At start
At end
mom.N
mgm.N
mgm.N
mgm, N
0.69
3.86
mgm.N
mgm. N
17.14
7.28
mgm. N
0.88
10.65
mgm.N
18.02
17.93
Balances
•
+3.17
-9.86
+9.77
-0.C9
Experiment 79. A number of heavy walled Erlenmeyer flasks
of 300 cc. capacity received 50 cc. of a solution of the following
composition :
Deep well water 500.00 cc.
KsHP04 0.25 gram
NaCl 0.25 gram
FeSO* + 7H,0 0 . 025 gram
Glucose 5.00 grams
Another set of flasks received 50 cc. of this same solution to
whicli had been added 0.115 per cent of KNO«. The flasks
were all fitted as is shown in the accompanying figure 3 with
manometer tubes.
They had all received in addition to the solution 0.25 gram of
precipitated CaCOt. One flask in each series (nos. 1 and 5) was
left uninoculated to serve as control while the others were inocu-
lated with a pure culture of Azotobacter chroococcum. After
varying periods of incubation at 27^C. the gas was pumped out
of the flasks by means of a mercury pump until the solution
boiled at about 30^C.; then boiling was continued for a few
minutes, and the gas mixture thus obtained was analyzed. The
STUDIES ON AZOTOBACTER CHROOCOCCUM BEU.
343
solution was then used for the determination of the residual
sugar. The results are presented in tables 9 and 10.
Expressing these values in terms of cubic centimeters of gas in
the total volume of the flasks at O^C. and 760 mm. we have the
result shown in table 10.
Fio. 3. a, culture flask; b, manometer tube (Hg rose to atmospheric pressure
when evacuated); c, evacuation tube and gas collector connection; x, paraffin
coating on rubber stopper. *
If now we consider all the oxygen disappeared to be used in a
process of combustion such as is expressed in equation 2 on
page 338, we have the data given in table 11.
In the above data we find confirmation of the hypothesis
expressed above. Azotobacter utilizes the sugar first in the
biulding up of its cell substance and the preparation of non-
reducing substances; and slowly digests these "stores" of car-
bonaceous material in the process of later development in the
344
AUGUSTO BONAZZI
presence of oxygen. It is also reasonable to assume that the
energy resulting from this oxidation is utilized in further growth.
If this were actually the case, it should be possible to follow these
various steps and the coincident disappearance of sugar at close
intervals of time, in a solution undergoing active fermentation.
TABLE 9
Be$tdU of ga$ analyBes of cttUvreB of Atotobacter under oxygen Biarvation expreeud
in percentage of the gae mixture
HO RlTRATa
QAS
Number of flaak
Number ol fladc
1
a
8
i
6
6
7
8
COf
0.00
20.32
17.61
0.49
17.64
1.94
0.00
20.27
17.96
0.80
19.87
0.97
Ol
TABLE 10
Gae and sugar changee in cuLiuree of Atotobaeter
TBSATMSm
WXTIIBaB
DATS or
IHCXJ-
BATXOXr
OZTOBir
OOmUMBO
CABBON DIOXID
VOBMBD
•OOAB
OOM-
■UMBD
OOi
Os
None
2
3
6
7
3
4
3
4
ee.
46.84
42.93
46.79
47.67
M0M.
66.49
61.33
66.41
68.10
ee.
40.48
42.16
42.24
49.08
mem.
79.61
82.82
82.97
96.41
mem*
86.20
76.80
70.00
72.80
0.88
Nitrate
0.96
0.92
1.03
TABLE a
Gae balancee in etdturee of Atotobaeter ckrooeoeeutn
niBAfiiBirT
mnaMM
DATS OP
DfCVBATIOX
CtHisOt
OOMSUICBD
ABOTB
TBBOBT
COi
VOBMBD ABOTB
OBBBLOW
TBBOBT
None
2
3
6
7
3
4
3
4
+24.80
+19.30
+8.68
+8.66
-10.49
Nitrate
+1.61
-6.97
+2.77
This method of study has been followed by Allen (1920) with
the results diagrammatically shown in the figure 4.
The sharp fall of the sugar contents during the period O-X'
from the quantity F to F' shows without doubt that the sugar
STUDIES ON AZOTOBAGTEB CHBOOCOCCT7M BEU.
345
is worked over by the cells during the early stages of cultivation
and is then slowly utilized by the cells in their later develop-
menty during that period when the sugar curve runs about
jMurallel to the asymptote (to the axis X).
In another experiment the following data were obtained,
corroborating the above statement.
fime in dax^s
Fig. 4
Experiment 61. Sugar consumption in large petri dishes of
20 cm. diameter:
FIBSr 6 DAT!
X BZr S DATB
NUET 6 DATB
SugAT coTiffumed . . .
316.7
63.0
M0M.
160.0
53.0
MffW.
0.0
Consumed per day during periods
0.0
Keeping in mind the fact that there are very few cells active
during the first five days, the number in fact being negligible
during the very first day or two, we can see that the first value is
much more than 63 mgm. of sugar consumed per day.^
^ Here it may be well to keep in mind the mathematical interpretation of
bacterial growth presented by Duclaux and discussed by him in volumes 1 and
2. This interpretation was later included by Rahn in his treatment of the fer-
mentive capacity of a single cell. Mich. Res. Bui. 10.
346 AUCFUSTO BONAZZI
It is unnecessary to present more data on this point since it
would all corroborate the above statements without adding
new facts of importance. It is nevertheless important to obtain
a crucial test of the actual storing and utilization of the stores
of the sugar carbon; such evidence follows.
Aviophagy of Azotobacter
That some of the sugar which disappears from solution during
the first few days or hours of growth is actually stored in the
cells is obvious in view of the fact that the carbon of the sugar
contributes to the synthesis of the compounds of the cell sub-
stance, but in addition as will be seen, Azotobacter presents an
interesting case of what Duclaux designates with the term
''ph^nom^ne de vie continue." This phase is one in which the
organism is really living on its own reserves and the by-products
of its previous life activities, just as yeast will continue to live
in a fermented mixture at the expense of the glycogen, glycerd
and succinic acid which it formed during its early stages of
development and active fermentation.
Eocperiment 19. Pure cultures of Azotobacter chroococcum
were made on Ashby's mannitol-washed-agar plates and allowed
to incubate for twenty-four hours.
The growths thus obtained were emulsified in 0.75 per cent
NaCl solution and asepticaUy placed in sterile test tubes. Slides
of this bacterial suspension were prepared immediately and after
forty-two and one hundred and fourteen hours' standing in the
incubator. They were stained by means of the Giemsa solution
which stains well the peculiar granulations studied in a previous
commiuiication (Bonazzi, 1915). Examining fifty microscopic
fields at random on each of the slides so prepared, and counting
the nimiber of cells containing granules (granulated), those
free of granules and those in which the granules have partially
disappeared (transitional) the following data were obtained.
The cells here classed as transitional are those in which the
granules had nearly disappeared or were greatly diminished in
size and could well be classed among the ungranulated. If this
were done the following table would be obtained.
STUDIES ON AZOTOBACTEB CHBOOCOCCI7M BELT.
347
From these data it seems evident that the stores which were
accumulated by the cells during the first twenty-four hours of
development on a complete medium were subsequently attacked
when no more sugar was at their disposal. Nevertheless it must
be stated that the granules may not be the only stores of the
Azotobacter cell, and it is very probable that the heavy gelat-
inous capsule described by various authors is also a storing as
weU as a protecting organ.
TABLE 12
Autopkagy of Azotobacter
HOX7BS OF ZMCrmATIGN
PER CXMT OF TOTAL MUMBBB OF CKLLB AS
Granulated
Transitional
Free of granulations
0
42
114
84.62
8.52
9.02
6.15
19.28
28.18
9.23
72.20
62.80
TABLE 13
Autopkagy of Azotobacter
BOUBS OF INCTTBATIOlf
0
42
114
ADTOPHAOBD CXLLB
15.38
91.48
90.98
Sugar: cells ratio
Among the assimilation products of Azotobacter we should also
consider such compoxmds as play only a transitory r61e in the
cell metabolism and are later secreted in the surroxmding mediiun.
Stoklasa believes these to be ethyl alcohol, lactic, acetic and
butyric acids, but we have seen that we should question his
results since we have reason to accept Krzmieniewsky's data and
Omeliansky's statements with regard to these formations.
That no fixed acids are present has not as yet been shown with
certainty (although Omeliansky points to their absence) while
no volatile acids have been found in an Azotobacter culture by
Krzmieniewsky. Repeated trials made in this laboratory in
the hope of finding whether the unaccotmted for sugar could be
348 AUGUSTO BONAZZI
found in the form of volatile acids, failed to reveal their presence
when the cultures were distilled in presence of tartaric acid.
Nevertheless, whatever these compounds are they do not seon
capable of stopping the development of Azotobacter as is shown
in the foUowing experiment.
Experiment 71. A series of flasks containing each 25 cc. of a
glucose solution, Ca(N03)s and CaCOs was inoculated with a
pure culture of Azotobacter chroococcwn and incubated at 30°C.
One flask was left iminoculated as a control. After the neces-
sary period of incubation had elapsed the solutions were acidified
imtil complete solution of the carbonate, allowed to stand in
this acidified condition for a short time and then filtered with
suction, through a crucible filter prepared according to the
accompanjdng illustration (fig. 5).
Fio. 5. a, perforated glac^d crucible ; &, glass wool; c, washed, digested, ignited
quartz sand; d, asbestos; e, packed and burnished platinum sponge.
The solutions passing through the filter were perfectly clear
showing that the cells were completely retained by the filter.
Careful washing with water, in small quantities at a time, insured
complete removal of the retained sugar. By this procedure it
was possible to separate the cells from the siurrounding medium
so as to form a conception of the riatio S:c where S is the sugar
consumed and c the weight of the cells produced, reckoned in
terms of cellular substance dried at llO^C. in vacuum, over
PA.
One of the above mentioned cultures, no. 5, was not filtered
but received instead the addition of 2 cc. of a 12.5 per cent
glucose solution xmder aseptic conditions; allowed to incubate
for a longer period of time it was then subjected to the same
STUDIES ON AZOTOBAGTEB CHROOCOCCUM BELT.
349
treatment as the others. The results of this experiment are
tabulated in table 14.
TABLE 14
Effect on the growth of Azotobacter chroococcum of its own by-products
NUMBBB
or
CTwrunm
1
2
3
4*
CtHisOt FOUND
DST MATTBB
DATS or
INCUBA-
TION
At ■tart
At and
ConauzMd
Conaumed
in Moond
period
Actual
Increaae
inaeoond
period
ll|0M>
mam.
mffm*
mam.
162.0
162.0
0.0
0
162.0
7.1
154.9
30
18.2
162.0
9.7
152.3
♦30
Lost
162+214.7
-376.7
376.7
0.0
376.7
6.2
370.6
216.9
38
27.3
9.1
8:o
IN BACH
PBBIOD
8.51
23.84
* Total quantity of sugar at the beginning of second period.
Addition of carbohydrate to a culture that had come to a
standstill wiU result in a new utilization of the carbon source
with further growth. The first compounds resulting from the
first utilization of the sugar had probably aU been utilized during
the first thirty days of incubation and only such by-products as
the cells could not well utilize were to be found when the culture
received the fresh supply of sugar; that these were not inhibitive
is shown by the utilization of the sugar in the second period as
well as by the additional growth. Their nature will be studied
elsewhere^ and at present it is sufi&cient to state that they are
formed through the cell activity.
Ferment powers of Azotobacter
From table 14 we may see that the conception S : c is erroneous
with regard to the data for culture 5. In fact while it is true
that there was a renewal of growth in the second period with a
corresponding increase in dry matter, we are not justified in
considering that it was only the 9.1 mgm. additional growth that
consumed the additional sugar, but we should deem it possible
that the 18.2 mgm. of the cells already present in the culture
used the new source of carbon for their maintenance. In other
360
AUOUSTO BONAZZI
wordS; referring to equation 1 set forth on page 335 of this
memoir we may well express our hypothesis as follows: during
the first period of incubation there was a balance between the
two functions represented by the equation, while in the second
period of incubation the addition of sugar disturbed the balance
in such a way that although the first member of the second
term was active on 9.1 mgm. of new cellular substance, the
second member of this term was active on a total of 9.1 + 18.3
= 27.4 mgm. This leads us to the conclusion that the concep-
tion of ^^ ferment power^' in an organism such as Azotobacter
should be carefully studied. The following series of experiments
was therefore designed to study this phase.
Experiment 69. Some 250 cc. Erlenmeyer flasks received
50 cc. of the following solution together with 0.5 gram of precip-
itated calcium carbonate.
Deep well water 500.00 cc.
K,HP04 0 .25 gram
NaCl 0.25 gram
FeSO« + 7HiO 0.02 gram
Glucose 5.00 grams
Ca(NOi)i + 4HaO 0.632 gram
TABLE 15
Sugar consumed per unit of dry matter in cultures of Azotobacter
NUIIBEB Oy
DATB OF
XMCUBATIOM
8UOAB
COMBClfBD
DBT MA1TBB
OFCEXXS
▲WDSLOfB
8
:e
CUI/rURB
Actual
By periods
mgrn.
mom.
•
5
0
0
0.0
0.00
0.00
6
3
65
Lost
7
5
109.8
12
9.15
9.15
8
23
411.5
62
6.63
6.03
After inoculation with equal quantities of a pure culture of
Azotobacter chroococcum the flasks were incubated at 30^C. for
varying periods of time. One of the flasks was left iminoculated
to serve as control. The dry matter in the cultures was deter-
mined by acidifsring, filtering in the manner referred to above,
washing and drying at llO^C. in vacuimi over PjOj, while the
sugar was determined in the filtrate. The results are set forth
in table 15.
STUDIES ON AZOTOBAGTEB CHROOCOCCUM BEU.
351
Before entering into a discussion of the above data other
experiments will be related.
Experiment 81. Twenty-five cubic centimeters of the solu-
tion mentioned in the previous experiment were placed into 1500
cc. Erlenmeyer flasks together with 0.25 gram of CaCOa and
sterilized; inoculated with equal and very small quantities of
TABLE 10
Sugar coiwumed per unit of dry matter in cultures of Atotohacter — experiment 81
MUVBBBOr
DAT* or
INCUBATION
BUOAR
CON8UMSD
DKT MATTXB
OFCBIXa
AND BUUm
8:o
OUX/rUBB
Actual
Byperiodi
6
7
8
9
10
0
1
2
4
9
0.0
1.4
4.4
69.2
184.8
0.0
0.0
0.0*
6.3
24.8
0.0
10.9
7.4
0.0
10.3
6.2
* Pronounced opalescence of solution too little to be weighed.
TABTiE 17
"Ferment power" of Atotohacter chroococcum
DATS or INCUBATION
FBRMXNT POWXB S: C.t*
30
23
9
5
4
0.28
0.29
0.82
1.83
2.74t
* S:c.t, where S sugar consumed, c cellular dry matter and t time in days.
t This value is in reality calculated differently from the others. But since
on the second day of incubation no appreciable amount of cell substance was
formed (experiment 81, no. 8) we should be justified in calculating this value just
as the others, i.e., on the base of a two days' growth; thus a "ferment power"
-5.45.
Azotobader chroococcum and incubated at 30®C. for varying
periods of time. The same analytical technique was used in the
analysis of these as in the cultures of the previous experiment.
Comparing now the data presented in tables 14, 15 and 16 we
see that the culture incubated thirty days gave a S : c ratio of
352
AUGUSTO BONAZZI
8.51 while the culture incubated twenty-three days gave a value
6.63 — of approximately equal magnitude. From these data we
can draw a very interesting set of figures if we consider the
actual ^^ ferment power" per day. The term ^* ferment power"
5
- 1
c.
•
)4
• 1
o
Q.
C
•
E5
1
U
^2
1
«
3
"5
>
1
■
0 10 20 ao
unit5 ^ time
Fio. 6. • «■ value of 4 day period on 4 day basis; o -> value of 4 day period
on 2 day basis (see text).
as used by Pasteur and modified by Duclaux to include the tune
element gives valuable indications as to the physiology of Azoto-
bacter (see table 17 and fig. 6).
The term ''ferment power" is here used to designate that
quantity of sugar consumed by the unit of dry cell substance in
the unit of time under the conditions of the experiments. This
concept leads us to the conclusion that during the early stages of
STUDIES ON AZOTOBACTER CHROOCOCCUM BEU. 353
development in a culture there is a greater transformation of
the crude food substances than dming the later stages, a con-
clusion that is corroborated by the opinion expressed in the
previous pages.
We see thus: 1, that the term ''ferment power^^ should not be
considered as a fimction, constant throughout the life cycle of
Azotobacter and, 2, that an organism such as this is capable of
utilizing the carbohydrate of a culture in a process of "storage''
or transformation without a corresponding cellular development.
General coneideratUma on carbon relations
In the preceding pages we have assumed that that quantity of
sugar carbon as such which disappears from the solution is to
be found in the cells and their by-products. That it is not to be
found in the cells themselves is shown by the high coefficient of
*' ferment power** in a yoimg culture of the organism in question,
since this value is based on that quantity of sugar that is "con-
sumed'' by the imit of cell substance in the unit of time.
Objection could be raised to the conception "imit of cell sub-
stance" only on the basis of numbers of active cells since the law
of multiplication, when all factors remain equal during the durar
tion of the experiment, makes the niunber of cells foimd at the
end of an incubation period equal to the number that has been
active throughout this period, provided the number of cells at
the beginning is considered as imity.*
Nevertheless the final weight of cellular dry matter in a cul-
ture represents the algebraic summation of the two opposite
phenomena of anabolism and catabolism, a value related not
only to the size of the inoculum itself, but also to the activity of
the organism concerned.
In other words, it furnishes an index both of the "growth
capacity" of the organism and its ability to build living bacterial
substance, as well as of its actual capacity as a ferment.
* Expressed in terms of equation: iV « n — 1 where N is the number of units
at the end and n is the number of units actually active during the whole period
of incubation, each unit of the same number of cells as the original inoculum
which has multiplied in geometrical proportion on incubation.
354 AXJGUSTO BONAZZI
We thus see that the sugar lost from a culture in the early
stages of development passes through the cells in large quantities
and is transformed into compounds which do not form integral
part of the cells themselves but are dissolved in the medium.
The curves of COi production given by Krainsky (1908, 1910)
might indicate the close relation between this function and
growth, which is pointed to by the values of the ferment power
here obtained.
This conception constitutes the conclusion to be drawn from
the discussion and closes, temporarily, the chapter on carbon
relations of Azotobacter. That it appears contrary to the con-
clusions of Erzmieniewsky and Qmeliansky and Prazmowsky is
evident, but it should be remembered that their search for
soluble by-products was performed ten days after the start of
the experiments, — ^probably when they had been already utilized.
This is significant in view of the fact that we failed to find vola-
tile acids in our cultures in conformity with the findings of the
above mentioned investigators.
Nitrogen relations — Attack on nitrates by Azotobacter
The organism with which these investigations were undertaken
was an organism from the Wooster soils that when grown in
twenty-five cubic centimeters of Ashby solution (1 per cent
mannitol) in 150 cc. Erlenmeyer flasks and incubated for fifty-
nine days at a temperature of 28°C. possessed a low nitrogen
fixing capacity.
Experiment 15.
B-l check uninoculated (mgm. Ni found) 0.66
B-^ inoculated culture (mgm. Ns found) 2.78
Nitrogen fixed (mgm.) 2. 13
Thus fixation calculated to the basis of 1 liter of solution
would give 85.2 mgm. fixed nitrogen; a quantity that represents
a fixation of 8.5 mgm. of nitrogen per gram of mannitol if we
assume all the mannitol to be utilized during the experiment.
STUDIES ON AZOTOBACTER CHROOCOCCT7M BEU. 355
When this same organism was grown in 100 cc. of a 2 per cent
mannitol solution in large Fembach flasks it fixed the following
quantities of nitrogen:
Experiment S9-31.
Ineubation in dav$
8 i7
Check uninoculated (zngm. Ns found) 0.66 0.97
Inoculated (mgm. Nt found) 3.61 7.47
Nitrogen fixed (mgm.) 2.95 6.50
Incubation was done on a klinostat where the solution was
kept in continual movement and the layer of solution was never
above 0.5 cm. deep. (Bonazzi, 1919.) The organism proved
itself to be a nitrogen fixer in the ordinary sense of the term, as
it was found capable of utilizing the atmospheric nitrogen.^
The mannitol in these cultures was not all constuned and it was
impossible to study the nitrogen fixation per gram of mannitol
consumed.
From the work of the various investigators quoted in the first
part of this memoir, it can be seen that AzoU^ader chroococcum
may utilize nitrates when grown in their presence. From the
data reproduced as table 1 of this contribution Hills draws the
following conclusion: "In regard to the fixation of nitrogen by
these strains of Azotobacter it was found that nitrogen was
assimilated both in presence and absence of nitrates. It
seems evident that sodium and anmionium nitrate in the
amoimts studied did not prevent the fixation of the atmospheric
nitrogen. In fact the presence of these salts seemed to stimulate
the process^" Again emphasis is placed on this interpretation
when the author states: ''However in contrast to the work
of Stoklasa, both strains of Azotobacter assimilated more atmos-
pheric nitrogen in presence than in absence of these salts."
From table 1 of the present memoir, where Hills' data are
recalculated we see that such conclusions are wholly imjustified.
Especially is this true when we consider that the analytical
method used for the determination of nitrates include the
nitrite nitrogen as weU. This speaks against the assumption
that ''the reduction of nitrates by Azotobacter takes place with
356 AU6U8TO BONAZZI
the formation of nitrites as is shown in table 14." By refer-
ring to table 14 of this author we find that 18.9 mgm. of nitrate
nitrogen were lost with a resulting "slight" reaction for nitrites in
the solution. A concentration of 18.9 mgm. of nitrites in 100 cc.
of solution (for that matter even much less than this) gives more
than a ''slight" reaction with such a sensitive reagent as the
Tromsdorff solution, and it is more than questionable if the
totality of the nitrate lost is to be found in the form of nitrites.
In addition the analytical data point to the incorrectness of this
view.
It is a common experience to see a good development of Azoto-
bacter in cultures containing nitrates while poor development
takes place in cultures containing no nitrate. For the sake of
argument we may assume that the nitrate acts solely in virtue
of the stimulation it is supposed to exercise on the nitrogen
fixing power of the organism. This increase in the nitrogen
fixing power, if present at all, is relatively small and amounts to
only 200 to 500 per cent of the original fixation; a stimulation
that, when we consider the small original fixation, is relatively
small. Although actual data are wanting, we may assiune this
stimulation to amount to 500 per cent (see the data of HiUs on
the influence of nitrates on the nitrogen fixation in sterilized
soils). A relative increase of 500 per cent in nitrogen fixation
brought about by an increase in the number of active cells of
3150 per cent represents an inconceivable stimulation in the
fixation of nitrogen, every cell actually fixing less nitrogen in
presence than in absence of the fixed nitrogen. It must further-
more be admitted that such a nitrate addition stimulates growth
in a different measure than it does nitrogen fixation. Here again
we obtain proof of the fact that the nitrogen fixing capacity of
the cell is not intimately connected with the function of growth
and reproduction.
If the stimulation hypothesis is to be accepted how are we
to consider such a difference in these two powers? We are in
reality more justified in considering the nitrates as stimulating
(or better still aiding) growth in the first place. Basing our
working hypothesis on the physiology of the organism we see
STUDIES ON AZOTOBACTEB CHBOOCOCCTTM BELT.
357
that the nitrates increase growth of the cells and their multipli-
cation with a corresponding increase in sugar consumption, and
in this process the nitrates disappear to be later found in the
organic form, and only after such a phenomenon has taken
place does the atmospheric nitrogen fixation really become
active.
Experiment S7. Fifty cubic centimeter portions of a solution
of the following composition were placed into 500 cc. Kjeldahl
jBasks together with 0.1 gram CaCOs.
Mannitol 20.0 grams
MgSOi + 7HjO 0.408 gram
NaCl 0.200 gram
CaSOi 4- 7HtO 0.127 gram
K»HP04 0.200 gram
Tap water 1000.00 cc.
TABLE 18
Nitrogen fixation hy Azotobacier in presence and absence of nitrates
TRKATimVT
None:
Check
Check
Inoculated..
Inoculated..
Nitrate : n
Check
Check
Inoculated. .
Inoculated..
Inoculated . .
Inoculated..
Inoculated. .
NlTBOaBirAS
ATKBAGB
or
OF TOTAL
NirBOGEN
NHi
NiOi
Oisftnie
Total
mfftn.
m^iit.
ffi^fii.
instil.
WQWo
1
0
0
2
0
0
3
*
4
0.81
0.81
0.81
5
0.25
5.43
*
6
0.21
5.30
1.76
7.35
7.35
7
0.19
4.37
1.98
6.54
8
0.18
3.79
1.98
5.96
9
0.17
4.50
1.89
6.56
10
0.13
4.54
1.96
6.62
11
0.15
4.10
0
6.38
MTTBOOBN
FIXED
mQn.
+0.81
-0.97
* Determination lost.
Eleven flasks were prepared and nmnbered successively from
1 to 11. They were arranged as follows: Nos. 1-4 inclusive
received in addition to the above solution 5 cc. of water and
flasks 5-11 inclusive received 5 cc. of a 0.843 per cent solution of
Ca(N0s)2 + 4H20. All the flasks except nos. 1, 2, 5, 6 were
358
AUGT7ST0 BONAZZI
inoculated with a pure culture of Azotobacter ckroococcum. After
an incubation of nineteen days at 30°C. the cultures were ana-
lyzed and found to give the values summarized in table 18.
Reference to the cultural notes shows that by far the better
growth was f oimd in the nitrate cultures during the whole period
of incubation.
An attack on the nitrate is here evident, without a quantita-
tive corresponding increase in the organic nitrogen. Further-
more a certain amount of nitrogen (that quantity which failed
to be organized) is actually lost from solution. Although the
data are not quantitatively conclusive; their qualitative signifi-
cance is paramount. They establish an actual loss from the
solution in direct corroboration of the results of Hills. Since
the depth of the solution layer may be responsible for the low
nitrogen changes obtained, trials were made with extensive
surfaces of exposure.
Experiment S2. Four large Fembach flasks received 100 cc.
of Ashby's solution together with 0.5 gram CaCOs; two of these
TABLE 10
Nitrogen fixed or lost by Azotobacter in absence or presence of nitraUs
TRBATMXMT
None:
Control. . .
Inoculated
Nitrate :
Control. . .
Inoculated
XUMBBB
or
CUIA'UBB
:
mrsooBN AS
Organic
and
ammonia
Nitioua
and
nitrio
Total
2
5
4
6
mom.
0.66
3.61
0.88
15.84
16.81
1.38
mom,
0.66
3.61
17.60
17.22
QAIirOB
+2.95
-0.47
flasks received 5 cc. of water while the other two received 5 cc.
of a 2.532 per cent solution of Ca(NO,)i + 4HiO. The flasks
intended for inoculation were sterilized and all the flasks then
received as infecting material equal amounts of a suspension of
Azotobacter chroococcum. After this the controls were sterilized
at the same temperature and pressure as the others.
STUDIES ON AZOTOBACTER GHROOCOCCUM BEU.
359
After eight days' incubation at 25°C. the cultures were ana-
lyzed and found to give the values shown in table 19.
Here Azotobacter is found to break down the nitrate and
actually change it into the organic form with a resultant loss
from solution.
Experiment 46. When the mannitol is replaced by glucose in
a solution of the following composition the nitrogen balances
vary only with regard to the quantity of nitrogen lost from
solution.
Glucose 5.00 grams
K1HPO4 0.06 gram
Ca(NO,)t + 4H,0 0.316 gram
Deep weU water 260.0 cc.
One hundred cubic centimeters of this solution pipetted into
large Fernbach flasks received 0.5 gram CaCOs. After inocu-
lation of one with a very small quantity of a pure culture of
Azotobacter chroococcum, the flasks were incubated for fifty-two
days at 25^C. Table 20 summarizes the results obtained.
TABLE 20
Attack of nitrates by Azotobacter ckroococcum
H UMBKB OF
TBBATiinrr
NrrBOOBN A8
cuuruRB
Organic and
ammonia
Nitrous and
nitrio
Total
BUGAB
0
1
Check
Inoculated
mgm,
0.88
10.65
mgfUt
17.14
7.28
mgm.
18.02
17.93
mgm,
1701.0
672.8
Differences
+9.77
-9.86
-0.09
-1128.2
Here again nearly the whole of the nitrate nitrogen reduced is
to be foimd in the organic form. As the loss of nitrogen from
solution is in this case negligible we may only draw attention
to it now and reserve discussion to a later page.
To establish with certainty the fact of nitrate nitrogen attack
and consmnption another series of experiments may be cited
which is typical of all the results obtained in this connection.
THB JOUBNAL OF BACTKBIOLOGT, VOL. VI, NO. 3
360
AUGXJSTO BONAZZI
Experiment 1^7. A solution prepared according to Gerlach
and Vogel constituted the basal medium.
Deep well water 500.00 cc.
KtHPOi 0.26 gram
NaCl 0.25 gram
FeSO« + 7HiO 0.01 gram
Glucose 5.00 grama
To 250 cc. of this medium 0.316 gram Ca (NO,), + 4H,0
were added. Fifty cubic centimeters of the nitrate solution
and of the nitrate-free solution were placed in very large petri
TABLE 21
Nitrate atiaek by Azotobacter chroococcum
NlTBOOBir AS
KUMBBB GF
TRBATHmr
aHHOBLOW
ouurvBa
Orcanioand
ammonia
Nitrous and
nitrio
Total
onrznoaBV
fll^M.
fii^fii.
moiii.
^^yWa
None
A-0^
Control
0.76
0.76
1
Inoculated
3.63
3.63
+2.87
2
Inoculated
4.43
4.43
+3.67
3
Inoculated
4.19
4.19
+3.43
4
Inoculated
4.50
4.50
+3.74
Average
+3.43
Nitrate
B-0*
Control
0.76
8.55
9.31
1
Inoculated
8.87
0.36
9.23
-0.08
2
Inoculated
8.64
0.43
9.07
-0.24
3
Inoculated
8.71
0.20
8.91
-0.40
4
Inoculated
8.84
0.25
9.09
-0.22
Average
-0.24
* Calculated from experiments 46 and 49 made with the same solutions.
dishes which had been sterilized with 0.5 gram CaCOs. Inocu-
lation of some of the dishes with a pm'e culture of Azotobacter
chroococcum was followed by incubation for twenty-four days at
25^0. The analytical results obtained are summarized in
table 21.
STT7DIES ON AZOTOBACTEB CHROOCOCCUM BEU. 361
The tabulated results require no further comment than has
ab-eady been made. The nitric nitrogen is all; or nearly all;
f oxmd in the form of organic or organized nitrogen.
The fact has thus been established that the nitrate nitrogen is
organized by Azotobacter in its process of growth but no insight
has been gained as to the modus operandi of this attack. A
review of the reported data on nitrogen relations seems to point
to the fact that the organism assimilates the nitrate in its early
stages thus causing a loss of nitrogen from the solution, but
later when the source of combined nitrogen is exhausted or
nearly exhausted, a second physiological phase sets in, in which
the cells assimilate atmospheric nitrogen, replacing thereby the
losses which the solution imderwent in its early stages. That
this seems to be what actually takes place in the cultures of
Azotobacter is evidenced by the accompanying experiments 51
and 55.
Experiment 51. Fifty cubic centimeters of a Vogel solution
to which 0.126 per cent of CaCNOs)^ + 4HsO had been added
were used; after inoculation and incubation at 25°C. for varying
lengths of time the cultiures were analyzed with the results
given in table 22.
Before discussing the results presented in the above table, a
new series of experiments aiming at the same end will be related.
The earUest incubation period of five days seemed to be too
long to allow a close study of the early assimilation of the nitrate
to be made. Shorter incubation periods were therefore observed
to obtain the required data.
Experiment 66. Fifty cubic centimeters of the same solution
as was used in the previous experiment were pipetted into sterile
petri dishes of 20 cm. diameters, containing 0.5 gram of CaCOg.
After inoculation and incubation for varying periods of time
the cultures were analyzed with the results set forth in table 23.
Although the actual amount of nitrogen imaccounted for is
jn many cases small, yet indications are that the modus operandi
of the nitrate attack by Azotobacter chroococcum may be stated
to be as follows; the organism utilizes the combined nitrogen
(in the form of nitrates) as soon as placed in contact with it and
362
AUQX7ST0 BONA2ZI
TABLE S2
Nitrate attack by Aeotohaeter
DATS OF
nrCUBATIOM
HITBOOBM AS
BUOAB
1J1IA0>
Nitric and
nitrous
Orgsniosnd
smmonw
l<OS
Control
5
5
8
8
13
13
mom.
8.66
1.12
mffm.
0.47
6.53
476.8
160.1
^^^vW«
Inoculated
Balance
-7.54
8.66
0.88
+6.06
0.47
7.41
-316.7
476.8
0.0
-1.48
Control
Inoculated
Balance
-7.78
8.66
0.72
+6.94
0.47
8.59
-476.8
476.8
0.0
-0.84
Control
Inoculated
Balance
-7.94
+8.12
-476.8
+0.18
TABLE 2S
NitraU attack by Azotobacter
DATS or
nfcuBATxoir
MITBOOmr AS
SVOAB
UIVAO
•
Nitric and
nitrous
Orcanioand
ammonia
oocirrxD
FOB
Control
2
2
5
5
7
7
9.34
5.79
0.13
3.70
511.6
361.0
-^
Inoculated
Balance
-3.55
9.34
1.82
+3.57
0.13
7.29
-150.6
511.6
103.0
+0.02
Control
Inoculated.
Balance
-7.52
9.34
1.02
+7.16
0.13
8.39
-408.6
511.6
12.4
—0.36
•
Control
Inoculated
Balance
-8.32
+8.26
-509.6
-0.06
STUDIES ON AZOTOBACTBB CHBOOCOGCT7M BEU. 363
causes a loss of this element under special conditions that are
not as yet completely understood. This loss may later be
replenished by this same organism in the process of 'Mater life/'
Apparently this second phase, phase of replenishment of the
lost nitrogen, is directly connected with the second phase of the
carbon metabolism studied in the preceding pages, since it
appears to take place after the reducing sugar has either dis-
appeared from solution or has been transformed into a non-
reducing substance. That this assimiption is justified is shown
by the fact that the nitrates have a special importance in the
carbon metabolism as is also shown by the data in the chapters
on the carbon relations.
Nitrates and fiUratUm of media
From the work of Allen (1919) we gather that filtration of a
culture solution, under the conditions designed to remove the
phosphates quantitatively, makes it unsuited for the develop-
ment of Azotobacter chroococcum. Although the addition of
calcium carbonate to the filtered solutions acted as a slightly
beneficial agent in bringing about nitrogen fixation, it was not
until phosphate was added in the form of tricalcium phosphate
that any appreciable nitrogen fixation took place. Unfor-
timately the criterion used by Allen in drawing his conclusions®
is subject to objection in the light of the above results so that in
the following study the sugar consumption and production of
bacterial substance was used as a measure of growth rather
than the fixation of atmospheric nitrogen. The phosphates
were replaced by nitrates, since some traces of phosphorus in
the soluble form were undoubtedly present in the solution.
Experiment 69. A solution of the following composition was
prepared and filtered, after a short standing at room tempera-
ture, over a coarse filter paper.
Deep well water 500.00 cc.
K,HP04 0.25 gram
NaCl 0.26 gram
FeSOi + 7H,0 0. 02 gram
Glucose 5.00 grams
' Fixation of atmospheric nitrogen.
364
AUQUSTO BONAZZI
To 250 cc. of the filtered solution were added 0.316 gram
Ca(NO«)j + 4H2O and 50 cc. were pipetted into each of several
250 cc. Erienmeyer flasks of Jena ^ass, containing 0.5000 gram
of CaCOs weighed on an anal}rtical balance. After sterilization
and inoculation with a pure culture of Azotobacter chroococcum
the flasks were incubated at 30°C. for varying periods of time.
Sugar detenoinations were made as well as determinations of
the dry matter in the cultures after acidifjong with HCl; the
dry matter reckoned on the basis of the substance at llO^C. in
vacuum over PjOs.
TABLE 24
DATS or
NONITBATS
NITBATK
INCUBA-
TION
Cultural
ohancten
Susar
OODSUIXMd
Cell
Bubstanoe
Cultural eharaoton
Sugar
oonsumad
CeU
Bubfltaaee
3
5
23
No growth
No growth
No growth
mgm.
0
0
0
mgm,
0
0
0
Distinct turbidity
Good growth
Good growth and
pigment
mgm.
65.0
109.8
411.5
12
62
Although the evidence seems at first sight to throw a shadow
of doubt on the theory of phosphorus hunger in the filtered
cultures, closer analysis shows it to corroborate the conclusions
of Allen.
The nitrate used was tested for phosphorus by means of the
ammonium molybdate reagent and f oimd to be phosphorus free.
The attempt was also made to avoid secondary reactions on any
phosphates which might have passed through the paper by using
Ca(N08)2 instead of any other nitrate, but the aim might not
have been fully reached. And this in spite of the work of Cam-
eron and Hurst (1904) in which they found calcium nitrate to
depress the concentration of the PO4 ions in a solution of CsLi(POi)t
in presence of the soUd phase.
in. DISCUSSION AND CONCLUSIONS
Azotobacter chroococcum Beij. when grown in synthetic solu-
tions presents a complicated physiology. Its carbon relations
seem to vary with the age of the culture, and are deeply affected
OTUDIBS ON AZOTOBACTEB GHBOOCOGCX7H BBU. 365
by the presence or absence of combined nitrogen in the solution.
These carbon relations are in reality so closely connected with
the nitrogen relations that to treat them separately would make
the discussion abstract and imsound.
The fact that the cells seem to attack the sugar with a respir-
atory quotient of COsKDs - db 1 is apparently misleading and
is not corroborated by a study of the sugar consumption. As
we have seen we are forced to admit a first phase in the sugar
metabolism, a phase that could well be named one of prepara-
tion, one in fact in which the sugar is worked up and changed
into a compound or compounds of a non-reducing nature. From
the study of the gas exchanges, it appears that the presence of
nitrates aids in the better utilization of the sugar. (Tables
7 and 11.)
In this first stage, the ^'ferment power" of the organism is
great and it is probably in this stage too, that the nitrates play
an important r61e; in fact it is at this stage that the nitrate
assimilation is at a maximum and evidence leads us to beUeve
in a close relationship and interdependence of the two exalted
fimctions, high ^'ferment power'' and nitrate disappearance.
Chu* filtration experiments before inoculation give us a proof
of the paramount importance of nitrates in the process of sugar
utilization, and, although the interpretation to be given to these
facts is as yet unknown, evidence leads us to the belief that
nitrates perform an intermediary function in the sugar fermen-
tation and assimilation and it may well be that this preparation
stage is directly dependent upon the formation of sugar-nitrate
complexes analogous to the phosphate sugar complexes of
Harden and Young.
In Allen's filtered solutions phosphates proved indispensable
probably on accoimt of their necessity in the formation of com-
plexes of the hexose-phosphate type. The fact that nitrates
proved to behave in a like manner leads us to the belief that
Azotobacter cells may be capable of attacking complexes of the
hexose-phosphate type as well as some homologues that involve
the nitrate radicle.
366 AUOUSTO BOKAZZI
The difference between the action of phosphates on zymase
action and of the nitrates on cell metabolism lies in the fact
that the nitrate proves to be actually organized by the cells
whereas the phosphate in the work of Harden and Young is
merely provisionally tied in an undisturbed form.
That this difference might be due to the fact that in the one
case we are dealing with a ^'figuraied^' ferment while in the other
we are only in presence of specific enz3mae is not to be overlooked
and investigation along this line may prove to us the possibility
of this line of reasoning. In fact, the locahzation of the organ-
ized nitrogen in the Azotobacter cultures might be intracellular
as well as extracellular and studies on this point would enhance
our knowledge of the physiology of the organism concerned
Such studies are now under way in this laboratory.
In the second or maintenance phase, such complexes appear
to be reworked, partially burned, partially utiUzed in the build-
ing of cellular substance and partially secreted in the surround-
ing medium in the form of soluble by-products. During this
phase the nitrogen is actually assimilated, directly contrary to
the belief of Hills.
A loss of nitrogen appears to take place during the first phase,
a loss which, if slight, may be again made up in the second phase
of development. The complication brou^t about by this first
phase in the interpretation of the results does not render the
term "ferment power" valueless or render useless the meaning
adopted by Duclaux for this term but is only an example of
what should be expected when studying the physiology of bac-
teria. Examples of a similar nature are not wanting in other
branches of science and mention need only be made here of the
limited value of the respiratory quotient in the study of the
physiology of the Crassulaceae among plants and of Ascaris and
Lumbricus among animals.
In concluding a word may be said of the practical interpre-
tations of the above findings.
The activity of Azotobacter as a fixer of atmospheric nitrogen
in the field is not easily demonstrated. Actual gains due to this
organism in the nitrogen contents of a soil in the field are seldom
STUDnCS ON AZOTOBACTER CHBOOCOCCTTM BEU. 367
positively shown whereas it would be assumed that a nitrogen
fixation from the atmosphere by the action of non-symbiotic
nitrogen fixers should take place at an active rate to judge from
laboratory experiments made in selective media and in absence
of combined nitrogen. Yet a study of the subject will show
that soils are only exceptionally free of nitrates and that these
are easily washed away. It is therefore the belief of the present
author that Azotobacter rather than serving as an active nitro-
gen (free) gatherer, may act to immobiUze the nitrate nitrogen,
taking the upper hand over the denitrifiers, and, to a con-
siderable extent, stopping the mentioned percolation.
By this it should not be understood that the organism is
hereby assumed to be lacking in all power of nitrogen fixation,
but only that this function is not to be considered as an all-
important phenomenon always active to the full benefit of man
and to the detriment of the active organism itself, as it appears
that *'aU^' organisms choose the line of least resistance for obtain-
ing and assimilating their food; and microorganisms are not an
exception to the rule in spite of the arbitrary classification that
is made of them into ''benefidaV and ^'non-^nsficidl,''
That these experiments were made in solution does not detract
from the conclusions derived therefrom, since we have seen that
an obhgate aerobic function such as nitrite formation, when
studied by the methods used in this memoir may be advantage-
ously compared with this function in soils.
IV. METHODS
A word is probably necessary on the methods used in the
analysis of the cultures. The procedure used for the determi-
nation of ammonia, nitric and organic nitrogen on the same
sample has been outlined by Davisson elsewhere (1918). The
ammonia determinations were done by aeration over 5 grams
sodium carbonate and subsequent distillation into standard
acid. Subsequent treatment of the material in the aeration
flask with 2.5 cc. of concentrated sulphuric acid, to destroy the
carbonate, followed by 2 cc. of 50 per cent sodium hydroxid
368 AUGUBTO BONAZZI
and distillation into diluted acid (30 cc. H2SO4 in 30 cc. HiO)
for thirty minutes served to collect any ammonia resulting from
the hydrolysis of the organic substances in the alkaline liquid.
The solution was then diluted back to approximately 250 cc.
and the nitric nitrogen therein contamed determined by reduc-
tion and distillation from the alkaline solution in presence of
2 grams of Devarda's alloy. The acid solution containmg
the ammonia resulting from the hydrolysis of the organic matter
was then transferred to the Kjeldahl flask containing the
residue from the nitrate determination and the solution digested
for the determination of organic nitrogen. The solution was
digested until excessive frothing had ceased, then 10 grams
potassimn sulphate were added and digestion continued for one
hour after the solution had become bluish-green. It was then
distilled through an aU-glass apparatus.
When it was necessary to determine the total nitrogen includ-
ing the nitric nitrogen, the procedure developed in this laboratory
was adopted (1919).
The sugar was determined in the solutions by clearing with
colloidal iron and the centrifuge, using the clear liquid for the
reduction of the Fehling solution as recommended by Sha£fer
(1914) and titrating the cuprous oxid by means of 0.05 N. potas-
sium permanganate after dissolving it in Bertrand's solution.
This solution was previously made pink by the use of the per-
manganate solution to avoid errors in the determination.
Thanks are here due to Dr. E. R. Allen for making this work
possible and to Mr. B. S. Davisson for his kind assistance in
carrying through the niunerous nitrogen determinations.
REFERENCES
Allen 1015 Jour. Ind. Eng. Chem., 7, 621.
Allen 1019 Ann. Missouri Bot. Gardens, 6, 1--44.
Allen 1020 Ann. Missouri Bot. Gardens, 7, 75-70.
Bbijbrink and VanDelden 1002 Centr. f. Bakt. II., 9, 3-43.
BoNAZzi 1015 Jour. Agr. Res., 4, 225-230.
BoNAZZi 1010 Jour. Bact., 4, 43-60.
Cameron and Hurst 1004 Jour. Am. Chem. Soc., 96.
STUDIES ON AZOTOBACTER CHBOOCOCCUM BEU. 369
Dayisson 1018 Jour. Ind. Eng. Chem., 10, 600.
Dayisbon and Parsons 1910 Jour. Ind. Eng. Chem., 11, 306.
DucLAUX 1808-1900 Traits de microbiologie, 1 and 8*
Greaves 1918 Soil Sci., 6, 163-217.
Hbinzb 1906 Landw. Jahr., 86, 888-010.
Hills 1918 Jour. Agr. Res., 12, 183-230.
Koch u. Setdel 1912 Centr. f. Bakt. II., 81, 570-577.
Krainskt 1908 Centr. f. Bakt. II., 90, 725-736.
Krainbxt 1910 Centr. f. Bakt. II., 26, 231-235.
Krzhibnibwskt 1908 Bull. Inter. Ac. Scie. Cracovie, Juillet, p. 929.
LiPMAN 1903 N. J. Ezp. Stat. Rept., 24, 217-285.
Uax± 1902 Ann. Inst. Pasteur, 16, 195-346-433.
Omblxanskt u. Sewerowa 1911 Centr. f. Bakt. II., 29, 643-650.
Omeliansxt T7. Sibber 1913 Hdppe-Zeyler Zeitschr. Physiol. Chem., 88, 445-
459.
SHAFrsR 1914 Jour. Biol. Chem., 19, 285.
Stoklasa 1908 Centr. f. Bakt., II., 21, 484^509; 620-^32.
Stoklasa 1908 Centr. f. Bakt., II., 21, 620-632.
Stranax 1909 Zeitschr. f . Zuckerind. Bohmen. Jahr. 88, 599.
SPIRAL BODIES IN BACTERIAL CULTURES
LAURA FLORENCE
From the Department of Animal Pathology of The Rockefeller Institute for Medical
Research, Princetonf New Jersey
Received for publication November 12, 1920
During the winter of 1918-1919, in the course of some work with
spore-bearing bacteria, spiral bodies resembling spirochetes were
frequently found in cultures. When these were shown to Dr.
Theobald Smith, he suggested that they were clusters of detached
flagella such as had been seen by him at different times in cultures
of anaerobes. Two interesting coincidences occurred at this time.
The first was the receipt from an Institution of photographs
of similar spiral bodies with the suggestion that they might be
Vibrio fetus of infectious abortion in cattle, and the second was
the publication of an investigation into spiral bodies in bacterial
cultures by Koga and Otsubo (1919a). Since these authors have
discussed the phenomenon as one hitherto undescribed and since
their pubUcation has more recently (1919b) appeared in Japan, it
seems appropriate to call attention to earUer references and de-
scribe briefly the conditions under which these spiral bodies have
now been found.
Loeffler (1889) first saw these spiral bodies when staining the
flagella of the tjrphoid bacillus and the potato bacillus, but did
not recognize their true nature until a year later (1890), when he
f oimd them in three different blood serum cultures of the bacillus
of black leg. The latter were much larger than those seen in the
typhoid Cultures and he pubUshed, along with the description, a
photograph of the preparation. At the same time he referred to
a microphotograph, published by Frankel and Pf eiffer, of the
bacillus of maUgnant oedema in which spiral threads passed out
from the organism just as he had found them in the typhoid bacil-
lus. Three years later Sakharoff (1893) described and photo-
371
JOUBNAL or BACrXBIOLOOT, VOL. TI, XO. 4
372 LAURA FLORENCE
graphed spiral bodies found in cultures of an anaerobe, BaciUtis
asiaticus, isolated by him from stools of cholera patient? and
grown in gelatin stab cultures. He agreed with the hypothesis
of Loef&er that these were made up of clusters of detached flagella,
since they could not be gotten rid of in long series of transfers
and varied considerably in length and thickness. Also they could
not be evolution forms of the bacteria, as dead spirals were numer-
ous in twenty-four hour cultures. In the same year Moore (1893)
wrote,
In the microscopical examination of well-executed preparations for
exhibiting the flagella three conditions have been universally observed:
(1) .... ; (2) there were a considerable niunber of detached
or free flagella lying between the bacteria; and (3) the niunbers of
flagella on the different bacilli were not constant.
A more detailed account of these spiral bodies, also illustrated
by photographs, was pubUshed by Novy (1894), when he de-
scribed a new anaerobic bacillus of malignant oedema. He first
found them mistained in smears stained with Gentian violet of the
peritoneal fluid of guinea pigs and rabbits dead from inoculation,
and then well stained in smears prepared after Loefller 's method.
He found identical spirals in pure cultures of the organism and
thought the nature of the media to be in some way connected with
their formation. They occurred rarely in bouillon cultures.
They were more niunerous in gelatin cultures, most plentiful in
agar cultures, and in the two last cases they were found in the con-
densation water. LoeflSer 's work, but not that of Sakharoff, was
known to Novy and he confirmed the presence of these spirals
in cultures of the bacillus of black leg and found them also in
cultures of the bacillus of malignant oedema and of tetanus.
He was not, however, hke LoeflSer convinced that they were
clusters of flagella and he suggested the possibility of their being
single deformed flagella, analogous to the involution forms found
among bacteria, and named them ^'Riesengeisseln.'l
When studjdng the morphology of the tetanus bacillus Kanthack
and Connell (1897) found two types of flagella which they named
primary and secondary. Photographs of the latter show them
SPIRAL BODIES IN BACTERIAL CULTURES 373
to be similar to the spiral bodies under discussion, but the
authors found them always attached to the organisms.
Malvoz (1902) working with Wathelet foimd spiral bodies in a
culture of Bacterium coli isolated from the stools of a typhoid
patient. Preparations stained after Loeffler's method were
shown by them to Nuel (1893) who considered them identical
with spirals which he had found almost ten years earUer in cultures
made from a bacterial disease of the cornea. Like Novy he re-
garded them as individual flagella calling them ''cils grants."
Malvoz, however, inclined to Loeffler's view and referred to
Migula's description of their formation as the best. He called
them "cils compos6es," following the terminology of Sakharoff
in preference to that of Nuel.
That these spirals were known to bacteriologists at the end of
the last century is proved not only by Fliigge's (1896) brief
reference to them and Migula's (1897) account of their formation,
but by the remark of Zettnow (1899), " Geisselzopf e habe ich in
den jungen anaeroben Culturen nicht beobachtet. '' In the atlas
accompanying the first edition of KoUe and Wassermann (1902)
were published Zettnow 's photographs of small tufts of flagella
from a pure culture of an unknown bacterium and of a very large
tuft of flagella from Sarcina agilia. More recent references may
be found in the texts of von Hibler (1908), of Kolle and Wasser-
mann (1912), and of Friedberger and Pfeiffer (1919).
Koga and Otsubo (1919) while attempting to get pure cultures
of smegma spirochetes, f oimd spirochete-like spiral bodies in cul-
tures of saprophytic bacilli. The occurrence of such forms in
bacterial cultures was evidently unknown to them and the result of
their investigation led them to conclude that they were "nothing
more than an unusual development of the flagella or parts of the
bacterial bodies." They worked chiefly with Bacillus svbtilis
but gave a list of other organisms, in cultures of which spiral
bodies were also found.
For a number of years it has been the custom iq this laboratory
to keep certain cultures in tubes closed with sealing wax. In order
to find out the general effect on culture growth of such a method
a series of experiments with a number of spore-bearers was begun
374 LAURA FLORENCE
during the winter of 1918-1919. In the cultures of motile forms,
viz., Bacillus cereua, BaciUus mesentericus-fuscuSf BadUtis mes-
erUericus-vulgattis (2 strains), and a bacillus isolated from the lung
of a calf and designated "Organism A, " non-motile spiral bodies
resembling spirochetes were frequently seen. None such were
found in the cultures of non-motile forms being studied. All
the cultures were grown on plain agar slants and the tubes were
closed immediately after inoculation with paraffin-dipped cotton
stoppers cut off level with the top of the tube and then pushed
down approximately tV inch below the top. The mouth of the
tube was flamed until thoroughly hot, when a small amount of
sealing wax was placed over the stopper. This was absorbed by
stopper and, when the tube had cooled, the space above the stop-
per was filled with sealing wax care being taken to leave no air
bubbles. Several series of cultures were also grown in bouillon
sealed in the same way as the agar.
Spiral bodies were found in cultures of all five organisms, but
they appeared with greatest regularity in the two strains of
Bacillus mesentericus-uvlgatv^, in cultiu'es of ^hich Loeffler (1889)
had also found them. At first it was thought that they were to
be found only in sealed tubes, but later it was discovered that
they were always present in the condensation water of twenty to
twenty-four hour unsealed cultures of BadUus meserUericus'
vulgatus. They were also found in unsealed cultures of BaciUus
mesenteHcus-ifuscus and BaciUus cereus after the third day. They
were seen first in hanging drops made from the condensation water,
but were not found in smears made from the same and stained
with methylene blue or carbol f uchsin. However, in smears .
stained after Loeffler 's method they were always found well
stained; but, if Johnston and Mack's modified method was fol-
lowed they were not found, doubtless because they had disin-
tegrated during the prolonged iucubation in sterile water. Even
in young cultures spirals of different sizes were seen, but very large
ones, similar to those of the bacillus of black leg photographed by
Loeffler, were found only in sealed cultures after an incubation
period of fourteen to twenty days. In these large spirals striations
parallel to their longitudinal axis were frequently seen. Their
SPIRAL BODIES IN BACTEBIAL CULTURES 375
non-motility and reaction towards stains differentiated them
definitely from true spirochetes and their presence, in cultures of
motile organisms only, suggested a relationship with the flagella.
Further, their r^ular absence from preparations stained after
Johnston and Mack would seem to prove that they were lifeless.
DISCUSSION
Since this phenomenon has been most frequently seen during the
investigation of anaerobes, it has been thou^t that anaerobiosis
and the formation of spiral bodies were in some way connected.
It is now evident, however, that they are formed in aerobic cul-
tures. We have found them exclusively in the condensation
water . of such cultures and in its rapid drying out may rest the
explanation of their having been so frequently missed. SakharoflF
(1893) when studjring an aerobe, found them in hanging drops of
the liquefied gelatin and there as in BacilliLS iTieserUericus-vulgatiiS
a stout peUicle had grown over the surface of the liquid. It may
be said that under such a pellicle anaerobic conditions exist, but
spiral bodies were found in the condensation water of BacilliLs
cereus and Bacillus meaenUricuS'-fuscus after the third day, when
no pellicles had formed. Also, both Loeffler (1890) and Moore
(1893) found them in stained preparations of the typhoid bacillus
made from cultures which they do not say were grown anaerob-
ically. Koga and Otsubo (1919) found them in cultures of a
number of bacilli but all were cultivated anaerobically. They
further claim to have found flagella on PfeiffereUa mallei and
spiral bodies in their anaerobic cultures of this form.
In the earliest references no emphasis was laid on the nature
of the media on which the organisms were cultivated. Novy
(1894) was the first to suggest a relationship between the media
and the formation of spiral bodies. Our findings agree with his
in that spiral bodies were most abundant in the condensation
water of cultures grown on agar slants and were very rare or
entirely absent in bouillon cultures. We have not used gelatin.
Koga and Otsubo (1919) state that spiral bodies did not develop
at aU in media lacking fresh protein and were never found, when
376 LAXJKA FLORENCE
the organisms were cultivated on agar. In explanation of these
opposite findings it may be suggested that the Japanese workers
studied only the colonies on the agar slants^ in which we have
never found spiral bodies^ and did not examine the contents of
the condensation water, where we have repeatedly found them.
These authors did not specify in what part of the cultures grown
on media containing fresh protein the spiral bodies were found,
but Loeffler (1890) described those found in the cultures of the
black leg bacillus as lying on the surface layer of the blood serunu
To Migula's (1897) description of their formation as a mechani-
cal process resulting from the collision of motile bacteria and the
intertwining of their flagella in a circmnscribed space nothing
definite can be added. It is possible, however, that the nature of
the media on which an organism is grown may exert a secondary
influence on their formation and may explain the variation in
their time of appearance in cultures of different organisms. It
was thought that the viscosity of the condensation water migiht
influence the formation of spirals, but this proved not to be the
case.
SUMMARY
Spiral bodies resembling spirochetes were found in cultures of
bacterial organisms grown aerobically, as well as in those grown ui
a limited amoimt of oxygen. They were regularly present in the
condensation of water of such cultures.
As has been pointed out by other workers, such spiral bodies
are to be distinguished from spirochetes (1) by their lack of
motility, (2) by their reaction towards stains, and (3) by the
impossibihty of obtaining them in pure culture.
Their relationship with flagella is further proved by their pres-
ence in cultures of motile organisms only.
Their disintegration when incubated for two to three days
in sterile water is evidence of their lifelessness.
8PIBAL BODIES IN BACTEBIAL CULTURES 377
REFERENCES
FlI^ooe, C. 1896 Die Mikroorganismen. 3te Auflage.
Fbiedberoer, E., axd Pfbiffeb, R. 1019 Lehrbuch der Mikrobiologie.
Kanthack, a. a., and Connell, T. W. 1897 Journ. Path, and Bact., 4, 452.
KooA, G., AND Otsubo 1919a Joum. Infect. Diseases, 24, 56.
KoQA, G., AND Otsubo 1919b Kitasato Arch. Exper. Med., 3, 207.
KoLLE AND Wabsebmann 1902 Handbuch der pathogenen Mikroorganismen,
Atlas, erste Auflage.
Kolle and Wassebmann 1912 Handbuch der pathogenen Mikroorganismen,
Atlas, 2te Auflage.
LoEFFLSB, F. 1889 Centrlbl. f. Bakt., 6, 207.
LoEFFLEB, F. 1890 Centrlbl. f. Bakt., 7, 625.
Malvoz, E. 1902 Ann. Inst. Pasteur, 16, 686.
MiouLA, W. 1897 System der Bakterien.
MooBE, v. A. 1893 The Wilder Quarter-Century Book, 339.
NovT, F. G. 1894 Zeit. f. Hyg., 17, 209.
NxTSL 1893 Bull. Acad. med. Belgique.
Sakhaboff, M. N. 1893 Ann. Inst.. Pasteur, 7, 550.
YON HiBLEB, E. 1908 Untersuchungen Qber die pathogenen Anaeroben.
Zbttnow, E. 1899 Zeit. f. Hyg., 30, 95.
THE CAUSE OF EYES AND CHARACTERISTIC
FLAVOR IN EMMENTAL OR SWISS CHEESE^
JAMES M. SHERMAN
From the Research LaboraUniee of the Dairy Division, United States Department of
AgricvUure, Washington, D, C
Received for publication November 22, 1020
mTRODUCnON
Due to a lack of the proper natural inoculation in the milk,
the Swiss or Emmental cheese industry in the United States has
had only a limited success. The peculiar sweetish flavor which
is characteristic of the best cheese of this tjrpe is very commonly
lacking in oiu* American-made cheese. It is also frequently de-
ficient in eye development, and in fact in some cases the cheeses
are entirely ''blind." Swiss cheese is made only during certain
seasons in America, because of the imcertainty of obtaining the
proper development of eyes and flavor. It would seem that this
industry could be put on a soimder as well as a more scientific
basis by the use of cultures which would cause proper ripening
in the cheese. With such cultures at hand it should be possible
to make Swiss cheese of a imiform and high-grade quality through-
out the year; such practice should result in raising very materi-
ally the quality, as well as the quantity, of our American-made
Swiss cheese.
Von Freudenrich and Orla-Jensen (1906) in their work in
Switzerland have isolated propionic acid-producing bacteria
which they consider the cause of eyes in Emmental cheese. The
essential organism, called by them Bad. acidi-propicmiciia), was
f oimd to ferment lactates with the production of propionic acid,
acetic acid, and carbon dioxide. Other varieties of propionic
•
^ Published with the penniasion of the Secretary of Agriculture.
379
JOUBNAL or BACnWIOLOOT, TOL. TI, IfO. 4
X
380 JAMES M. SHERMAN
bacteria were found but they did not appear to have much in-
fluence on the ripening of cheese.
In the early experiments conducted by the Department of
Agriculture on Swiss cheese, some cultures of propionic acid
bacteria were obtamed from Professor Burri of Berne m the hope
that these could be introduced and used in the manufacture of
Swiss cheese in this country. The experiments conducted with
these cultures, however, were not encouraging; in fact it was not
established experimentally that they were able to cause the devel-
opment of eyes when used for starters in the manufacture of Swiss
cheese. Following the methods of Von Freudenrich and Orla-
Jensen, cultures were isolated which corresponded to their pub-
lished descriptions of the propionic-acid bacteria. These were
also used in the manufacture of experimental Swiss cheese with
negative results. These findings do not discredit the work of Von
Freudenrich and Orla-Jensen, since it is entirely possible that the
cultures used belonged to varieties which do not play important
rdles in the ripening of Emmental cheese. The experiments re-
ferred to were carried on a few years after the death of Professor
von Freudenrich; Professor Orla-Jensen at that time was not
able to furnish cultures of these organisms.
I. CONCERNING THE OCCUBRENCE AND NUMBEBS OF LACTATE-
FERBIENTING BACTERIA IN EMMENTAL CHEESE
That there exist in Emmental or Swiss cheese bacteria which
ferment lactates with the production of volatile acids has been
shown by Von Freudenrich and Orla-Jensen (1906), who suc-
ceeded in isolating such organisms in pure culture; and the theory
was advanced that the production of eyes is due to the carbon
dioxide liberated by these bacteria in the transformation of lactic
acid to propionic and acetic acids, according to the formula:
3 CH^O, « 2C,H«Oa+CJl402+CO,+HiO.
They also determined the approximate number of lactate-
fermenting organisms in Emmental cheese by means of dilution
cultures in a calcium lactate broth. By such methods they were
BYES AND FLAVOR IN EMMENTAL CHEESE 381
able to demonstrate that these bacteria occur in numbers from
10,000 to 200,000 per gram of cheese.
Troili-Petersson (1909) using the same methods found approxi-
mately the same numbers of lactate-fermenting bacteria as did
Von Freudenrich and Orla-Jensen. In a previous report from
these laboratories, Eldredge and Rogers (1914), who worked with
American cheese of the Emmental type, foimd this type of organ-
ism present in somewhat smaller numbers than was reported by
the European workers, and in fact apparently entirely lacking in
some cheese.
Modification of the lactate broth of Von Freudenrich and Orla-Jensen
For the growth and isolation of lactate-fermenting bacteria
from Emmental cheese, Von Freudenrich and Orla-Jensen (1906)
used a calcium lactate broth of the following composition:
Pepton (Witte) 2.0
Sodium chloride 0.5
Dipotassium phosphate .' 0.2
Calcium lactate 2.0
Although such a mixture is obviously faulty, due to the incom-
patibility of the calcium and phosphate ingredients, resulting in a
heavy precipitate of an insoluble calcium phosphate upon steriliza-
tion, the broth as used by Von Freudenrich and Orla-Jensen, so far
as we are aware, has not been modified by subsequent workers who
have used it extensively for studies of the propionic and butyric
acid-forming groups of bacteria. Only recently Boekhout and
De Vries (1917) have employed it in an extensive study of the
bacteria responsible for gas formation in cheese.
It need hardly be mentioned, assimiing that the several com-
ponents of the broth are in fact of value, that the ingredients
added should not be rendered inert by precipitation. This may
be obviated by the use of another salt of lactic acid, such as sodimn
lactate, in place of the calcium. The commercial sodium lactate
syrup may be used if desired, but we have found it convenient
to prepare the sodiiun lactate just before use by neutralizing the
desired amount of lactic acid with sodium hydroxide. The
sodium lactate broth has been found to be in all respects as good
382 JAMBS M. SHERMAN
as that made with the calcium salt, and in one very important
respect to be sui)erior.
In the preparation of the calcium lactate broth no attention,
so far as the published papers indicate, has been paid to its reac-
tion; and considering the reactions of the individual ingredients
employed there would seem offhand to be little need for concern
about this point. It was noted, however, when broth was tested
for its hydrogen-ion concentration, by means of the colorimetric
method of Clark and Lubs, (1917) that a value of about pH »
5.2 was always obtained. This result (from pH « 5.1 to pH «=
5.3) was found with Witte pepton as well as with a variety of
American brands.
An inquiry was therefore made into the reactions of the indi-
vidual components and of combinations of the several components.
Calcium lactate broth was made and at the same time solutions
of the various ingredients were prepared separately in the same
concentrations as they occur in the broth. These were all steri-
lized in the autoclave for twenty minutes at 15 pounds pressure.
After cooling, the following results were obtained :
2.0 per cent pepton 6.8
0.5 per cent sodium chloride 7.3
0.2 per cent dipotaesium phosphate 8.2
2.0 per cent calcium lactate 7.3
Von Freudenrich and Orla-Jensen broth 5.2
As is shown by these data, the reaction of the finished broth is
much more acid than is any one of its several components. An-
other lot of broth made with the same ingredients, with the excep-
tion that sodium lactate was substituted for the calcium salt, gave
a reaction of pH » 7.2.
It would appear then that the explanation is to be found in
the reaction between the phosphate and the calcium lactate; and
such it seems is the case, as is indicated by the result given below.
These solutions were sterilized as were those reported above.
PB
0.2 per cent dipotassium phosphate 8.2
2.0 per cent calcium lactate 7.3
0.2 per cent dipotassium phosphate +'2 per cent calcium lactate. . 4.8
EYES AXD FLAVOR IN EMMENTAL CHEESE 383
The marked acidity of the lactate-phosphate mixture is prob-
ably explained by the formation of acid phosphates and lactic acid
along with the insoluble calcium phosphate.
Aside from the case of this particular broth, the principle here
illustrated should be given more general consideration in the
formulation of culture media. It would seem, d priori, that there
is danger of such a shift in the hydrogen-ion concentration upon
sterilization of any medium which contains calcium or magnesium
and a phosphate, if the calcium-magnesiiun portion is in excess
of the phosphate. This principle is violated in many of the syn-
thetic media which are recorded in bacteriological literature. It
is obvious also that the buffering effect of the phosphate is lost
in such a combination.
In the recommendation that sodium lactate be used in the place
of the calcium salt, it has been assumed that the dibasic phosphate
employed in this mediiun serves some useful purpose. As a mat-
ter of fact, in pure culture, the lactate-fermenting bacteria of Swiss
cheese grow very well in broth containing only pepton and either
calciiun or sodium lactate. This does not prove that the simpli-
fied medium would be just as good for quantitative estimations in
which the seedings are very light.
In the work here reported quantitative determinations were
made in a broth containing 1 per cent pepton, 1 per cent dried
yeast and 1 per cent lactic acid (as sodiiun lactate). This broth
supports a very active growth of the lactate-fenhenters and is an
excellent one for quantitative purposes.
Approximate numbers found
Quantitative dilutions of cheese were planted in broth composed
of 1 per cent each of pepton, dried yeast, and lactic acid (in the
form of sodium lactate) . Dilutions of from 0.01 to 0.000,001 gram
of cheese were tested. After incubation for four weeks at SO'^C.
the cultures were acidulated and subjected to steam distillation
to determine the formation of volatile acids. Control flasks con-
taining pepton-yeast broth without the lactate, inoculated with
the same dilutions, were run, in order to avoid any possible error
through the measurement of the relatively small amounts of vola-
384 JAMES M. SHERMAN
tile acids derived from the nitrogenous constituents of the
medium.
Without going into details, it may be stated that of 16 samples
of American-made Swiss cheese purchased on the open market
all contained lactate-fermenting organisms in sufficient numbers
to be revealed in 0.000,001 gram, the highest dilution used. These
samples were representative of about the average run of domestic
Swiss cheese; only samples which had sufficient eye development
were taken, but the flavor varied from excellent to very poor.
Thus it will be seen that we have succeeded in demonstrating
the presence of lactate-fermenting organisms in numbers consid-
erably greater than has been reported by other investigators.
Also, as will be shown later on, these bacteria have been isolated
directly from cheese without previous enrichment in some selec-
tive broth.
Relation to previous work
Concerning the discrepancies between the results of various
workers on this subject, we feel that these inconsistencies may
well be reconciled through the observations made in connection
with the work here reported. As has been noted, the reaction
of the lactate broth, as employed by Von Freudenrich and Qrla-
Jensen and subsequent workers, is too acid for the best results.
The error which may be introduced by this factor is well iflus-
trated by the following test made on a pure culture of a lactate-
fermenting organism from Swiss cheese : A broth culture one
week old as tested by the dilution method, using the regular Von
Freudenrich and Orla-Jensen broth (pH = 5.2), and another broth
of the same composition except that sodium lactate was substi-
tuted for the calcimn salt. This broth had a reaction of pH =
6.8. The result of this test showed that, whereas the sodiiun lac-
tate broth gave a count of over 100,000,000 organisms per cubic
centimeter the number as indicated by the calcium lactate broth
was less than 1,000,000.
Aside from the error introduced through the unfavorable re-
action of the calcium lactate broth, as it has been previously used,
there are apparently other factors which make the dilution method
EYES AND FLAVOR IN EMHENTAL CHEESE 385
a rather uncertain one for the quantitative estimation of the lac-
tate-fermenting bacteria of cheese. It has been noted on several
occasions that the distillation for volatile acids gave negative re-
sults whereas further propagations from the culture used showed
that lactate-fermenting bacteria were present. This phenomenon
is probably to be explained by the presence in the culture of other
organisms which consmne the volatile acids. That this may
sometimes be the case was indicated by the results obtained on
certain samples of cheese in which volatile acids were produced
from the high dilutions of cheese in lactate broth whereas the low
dilutions, which contained a much heavier inoculation and a
greater variety of organisms, gave negative results. In this work
we have checked ourselves quite thoroughly against such errors
by running all of om* dilution cultures in triplicate, and also by
making further examinations and propagations from dilution cul-
tiu'es which gave negative results. Thus we have on several
occasions demonstrated the presence of the lactate-fermenting
bacteria from cultm^s which gave negative results on the original
test.
n. THE CAtrSE OP EYES AND FLAVOR
In our work on Swiss cheese during the past few years the
identity of the organism responsible for the development of the
characteristic flavor, as well as the eyes, of Emmental cheese has
been quite clearly established. The ability of this organism to
play these r61es in the ripening of cheese has not only been estab-
lished by carefully controlled laboratory experiments, but also
under practical commercial conditions in factories located in
widely separated areas of the coimtry.
GENERAL CHARACTERISTICS
Morphologically the organism is a minute rod about twice as
long as it is broad. It makes little or no growth on agar slope
cultures; in agar stabs growth takes place throughout the length
of the puncture but not on the surface. In agar shake cultiu^s
there is likewise no growth on the surface whereas good growth
takes place throughout the mediiun; as incubation continues over
386 JAMES M. SHERMAN
an extended period the growth is seen to become very heavy, bare-
ly below the surface of the agar. In a suitable nutrient broth a
heavy slimy growth occurs at the bottom and the whole broth be-
comes turbid, with the usual exception of a narrow clear zone at
the surface. Milk is rendered slowly acid and is usually curdled
in from one to two weeks at 30°C. Growth in pepton milk is much
better, curdling taking place in from four days to one week at
30^C. Small bubbles of gas may sometimes be seen in the curd.
Gelatin is not liquefied. Glucose, lactose, maltose, sucrose, gly-
cerol and salicin are fermented; raffinose, inulin, and mannitol
are not.
One of the outstanding characteristics of this organism is the
production of a large amoimt of catalase. Attention has pre-
viously been caUed to the relatively large amount of catalase which
is found in Swiss cheese (Sherman 1919). The group of organ-
isms herein described is the one which was shown to give this char-
teristic to cheese of the Emmental type.
Reference to the products produced by this bacterium indi-
cates that it belongs to the group of proprionic acid bacteria
which was described by Von Freudenrich and Orla-Jensen. Lac-
tates are fermented with the production of volatile acids, including
propionic and acetic, and carbon dioxide. Also in the fermenta-
tion of lactose, volatile acids and carbon dioxide are produced.
Relation to jrreviously described types
Whether this organism is identical with any of the tyi)es iso-
lated by Von Freudenrich and Orla-Jensen cannot be definitely
stated at this time. In general it appears to agree quite closely
with their description of J?acf . acidir-propionici (a) which they con-
sidered to be the true cause of the development of eyes in cheese.
A few points, however, in their description do not agree with the
characteristics which we have observed in our organism; they
state that it causes no visible change in milk, whereas our organ-
ism in litmus milk develops an acid reaction after several dajrs and
causes coagulation on longer incubation. Further, from their re-
sults on the production of volatile acids it was noted that only a
small amount of these substances was produced from glycerol,
EYES AND FLAVOR IN EMMENTAL CHEESE 387
while our organism causes an active fermentation of glycerol with
the production of a considerable quantity of volatile acids.
Finally, it may be stated that the organism with which we have
been working causes the typical sweetish flavor in Emmental
cheese, whereas the experiments of Von Freudenrich and Orla-Jen-
sen did not give definite results on this point. Orla-Jensen
(1912) has since stated more conclusively that the sweetish flavor
is due to a factor other than the propionic acid bacteria.
It is of course recognized that an accurate comparison can not
be made from published descriptions. It is hoped, therefore, that
we may obtain from European workers cultures of the various
types of propionic acid-forming bacteria so as to determine more
definitely whether this organism is identical with any of the pre-
viously described types or whether it is a new variety. In this
connection it may be noted that we have also isolated a variety of
these lactate-f ermenting bacteria, among which have been found
quite distinct types. Although the characteristics of all of these
varieties have not been studied in detail, they appear to agree
in a general way with the tyi)es which have been isolated by
European workers. It is hoped that further studies on these
organisms, in comparison with types obtained from Europe,
may be made in the future.
In keeping with the nomenclature used by ihe European
workers for the group of propionic acid-producing bacteria, this
organism will be tentatively designated as Bact. acidi-propumici (d) •
The isolation of cultures
The direct isolation of this organism from cheese is difficult
for various reasons, particularly because of its slow growth and
its oxygen requirements. Though not a strict anaerobe it
requires a considerably reduced oxygen tension. Although
in pure ciilture this organism grows in all ordinary culture
media, including even 1 per cent pepton solution, it is appar-
ently not so easy to obtain growths from it when taken directly
from cheese. On a few occasions colonies have been isolated
388 JAMES M. SHERMAN
from agar plates made directly from cheese; but success by this
method is rare.
On a niunber of occasions this organism has been isolated,
directly from the cheese, by sealing agar dilutions in glass
tubing of about 0.5 cm. diameter. With this method it is v^
easy to isolate the individual colonies by cutting the tube at
the desired i)oints. By sterilization of the outsides of these
tubes by immersion in a strong disinfectant solution, and then
rinsing with sterile water, there has been no difficulty in making
isolations by this method without contamination. The medium
which we have found very satisfactory for this purpose is one
consisting of 2 per cent pepton, 1 per cent yeast, 1 per cent
lactic acid (as sodium lactate) and 1.5 per cent agar. Although
we have had fairly good success in making isolations by this
method, it has by no means always proven successful.
By making enrichment cultures of the cheese in lactate pepton
broth, as was done by Von Freudenrich and Orla-Jensen, the
isolation of lactate-fermenting bacteria is much easier. We
have isolated a variety of organisms belonging to this group
from such enrichment cultures.
Our interest thus far has been more in the practical application
of these bacteria in the cheese industry than in making a thorough
study of their physiological characteristics. There is Uttle doubt
however, that by taking advantage of their known properties, a
simple differential method could be developed which would be
satisfactory for the direct isolation of this group of organisms
from cheese.
Rdle in cheese
For studying the effect of this organism in cheese we have
had at our disposal a supply of milk, obtained from the experi-
mental herd of the Dairy Division, which was entirely lacking
in the bacteria necessary for the development of the desired
characteristics of Emmental or Swiss cheese. Cheese made
from this milk by the Swiss method is always entirely lacking
in the characteristic sweetish flavor, and is also frequently
''blind." When the natural inoculation in this milk is such as
EYES AND FLAVOR IN EMMENTAL CHEESE 389
to cause a development of eyes in the cheese the resnltmg flavor
is in no way similar to that characteristic of the typical Swiss
cheese. This fact is important, since it shows that the forma-
tion of eyes may be due to bacteria other than the one herein
described; it probably explains also the fact that American Swiss
cheese is so frequently deficient in flavor even when abimdant
eye formation takes place.
In our laboratory work small cheeses of the Enmiental type
are made from about 200 pounds of milk. These cheeses are
then handled in exactly the same way as are the large Swiss
cheeses made imder factory conditions, and they ripen in an
entirely normal manner. From such experiments it has been
demonstrated time and again th^t the organism described in
this paper is responsible for the characteristic sweetish flavor
of Swiss cheese and that it also causes the development of eyes.
Its relation to the eye formation is shown in the photograph
reproduced at the end of this paper; its relation to flavor pro-
duction has been demonstrated in over 100 laboratory experi-
ments in which one cheese in each experiment was inoculated
while another cheese made from the same milk was left
iminoculated.
That the use of this bacterium as a "starter" is practicable
imder commercial conditions has been demonstrated in a number
of different factories. In all cases these factory experiments
have shown a marked influence on the ripening of the cheese
with respect to both eyes and flavor. The application of these
results in cheese-factory practice will be treated more in detail
in a future publication.
ACKNOWLEDGMENT '
Should the work herein reported prove of value to the cheese
industry, major credit therefor is due Mr. L. A. Rogers, in
charge of the Research Laboratories of the Dairy Division, who
recognized the possibilities of pure cultures in the manufacture
of Swiss cheese and initiated work toward that end over ten
years ago, and who has fostered and directed the work through
390 JAMES M. BHERICAN
a period of many discouragements due to lack of facilities and
frequent changes in the experimenting staff.
Acknowledgment is also due to Mr. K. J. Matheson, and his
several collaborators, whose cordial co6peration in conductiag
the cheese-manufacturing tests has made this work possible.
sumMabt
1. Bacteria capable of fermenting lactates with the production
of volatile acids have been found tq be constantly present in
normal cheese of the Swiss or Emmental type in niunbers exceed-
ing 1,000,000 per gram.
The discrepancies in the results of previous workers on this
subject are probably explained by a faulty combination of
salts contained in the mediimi used, resulting in the production
.of a reaction too acid for the optimum development of the
organisms concerned.
2. The essential organism for the production of eyes and
the characteristic sweetish flavor of Swiss cheese has been iso-
lated and studied.
The organism concerned belongs to the group of propionic
acid-producing bacteria, but appears to differ slightly in some
of its characters from the several varieties of propionic bacteria
which have been described in the Uterature.
Factory experiments have shown that pure cultures of the
organism may be used successfully in practice to insure the
proper ripening of Emmental cheese.
EYES AND FLAVOR IN EMMENTAL CHEESE 391
REFERENCES
BoBKHOUT, F. W., AND DbVribs, J. J. O. 1917 Study on the nonnal produc-
tion of gas in cheese. (Abstract) Abs. Bact., 2, 278.
Clabk, W. M. , AND LvBSy H. A. 1917 The colorimetric determination of hydro-
gen ion concentration and its applications in bacteriology. Jour.
Bact., 2, 1-34, 109-136, 191-236.
Eldredgb, E. E., and Roobbs, L. A. 1914 The bacteriology of cheese of the
Emmental type. Centbl. Bakt. (etc.), Abt. 2, 40, 5-21.
Orla-Jbnbbn, S. 1912 Der jetsige Stand der KSsereifungsfrage. Centbl.
Bakt. (etc.), Abt. 2, 82, 202-209.
Shbbman, J. M. 1919 The catalase content of cheese. Jour. Dairy Sci., 2,
453459.
Tboili-Pbtbrsson, Gbbda 1909 Studien dber in Kftse gefundene glyserin-
yergftrende und laktatverg&rende Bakterien. Centbl. Bakt. (etc.),
Abt. 2, 24, 333-342.
▼ON Frxtjdbnbich, E., and Obla-Jbnsen, S. 1906 Ueber die in Emmentaler-
kfise stattfindende Propionsftureg&rung. Landw. Jahrbuch d. Schweis,
320-638.
PLATE 1
The lower row of cheeses were made from milk lacking in the bacteria essential
for the proper ripening of Swiss cheese.
The cheeses in the upper row were made from the same milk as their respec-
tive ''blind" controls, with the addition of a pure culture of the eye and flavor
producing organism.
392
JOURNAL OF BACTERIOLOQY, VOL. V
A NEW MODIFICATION AND APPLICATION OF THE
GRAM STAIN
G. J. HUCKER
New York Agricvliural Experiment Staiion, Geneva, New York
Received for publication December 12, 1920
In making microscopical eicaminations of the quality of milk
received at New York state cheese factories a need arose for a
stain which would have a greater differential value than methy-
lene blue, and which would be applicable for quantitative as well
as qualitative results. The thought of the Gram stain at once
suggested itself. While organisms can be classified only into
general groups in methylene blue preparations, and no differen-
tiation can be made between desirable and undesirable types for
cheese making, the gas forming groups can be readily distin-
guished from the desirable lactic acid organisms in slides stained
by the Gram method.
In developing a modification of the Gram stain which could be
used in staining milk smears, the difficulty has been to secure a
decolorizing solution which would allow the Gram positive organ-
isms to retain the stain and still remove the color from the milk
and the Gram negative types. The following method has proved
satisfactory in our work, and is presented with the hope that it
will help solve similar difficulties for other investigators.
The stain is as follows:
Gentian violet solution
Anilin oil 3.0 cc.
Alcohol (absolute) 7.0 cc.
Water..: 90.0 cc.
Shake; filter
Gentian violet (GrQbler) 2.0 grams
«
Iodine solution
Iodine 1.0 gram
Potassium iodide 2.0 grams
Water. . . . : 300 . 0 cc.
305
896 G. J. HUCKER
Decoloriging 9oltUion
Anilin oil (2 partB) I . . ^ ^
Xylol (1 part )j "»«*™* ^P"*"
Alcohol (05 per cent) 05 parts
Counter stain
. Bismarck brown 4.5 grams
Water (boiling) 50.0 cc.
Filter
Alcohol (06 per cent) 30.0 cc.
•
The milk smears were prepared by the usual Breed method
(Breed and Brew, 1916) ; i.e., depositing 0.01 cc. of milk on a
clean glass slide and spreading with a needle over an area of
1 sq. cm. The smears were dried and placed in xylol until the
fat was dissolved, removed, drained, and immersed in 95 per
cent alcohol for two minutes for fixing. The slides before being
allowed to dry were placed in the gentian violet for forty-five
seconds, blotted or allowed to drain after removing from the
stain, and immersed in Gram's iodine solution for one minute,
destained in the anilin-xylol-alcohol solution until no more stain
could be removed; and then counter stained in Bismarck brown
for forty-five seconds.
Several formulas of gentian violet solution were used but the
particular concentration given has yielded the most consistent
and satisfactory results. Satisfactory preparations could not be
obtained with ''Method 1" (commonly known as Stirling mod-
ification) of the Report of the Committee on the Descriptive
Chart of the Society of American Bacteriolo^ts (Conn et aL,
1919) as light blue and green areas were deposited on the slide
when such concentrated gentian violet was used. This was espe-
cially true of smears prepared from milk which haxi developed
any degree of acidity. This reaction was probably due to the
conversion of the gentian violet into closely related dyes in the
presence of the acid and the alcohol of the destaining solution.
No definite data are available at present on this point. Th;
stains used in all cases were Griibler's.
The addition of the anilin oil and xylol to the destaining al-
cohol resulted in retarding the action of the solution sufficiently
NEW MODIFICATION OF THE GRAM STAIN 397
to allow the Gram positive organisms to retain the stain while
the color was removed from the Gram negative bacteria and the
background of milk. Hastings^ Evans and Hart (1912), in their
cheese work used a decolorizing solution of anilin oiF one part
and xylol two parts. This solution although removing the stain
from the Gram negative organisms and the milk, was slow
in action and caused the organisms to appear distended and less
brilliant in the final preparation. Consistent results could not
be obtained using alcohol as a decolorizer as the stain was re-
moved from the Gram positive bacteria before the milk was
sufficiently destained. The results obtained with acetone, as-
a decolorizer, were similar to those where alcohol was used.
With exception of Bismarck brown,^ no counter stain exhibited
sufficient range of affinity between the nucleo-proteins of the
cells and the casein of the milk to allow for different intensities
of color even if destained. A few successful smears were made
where an aqueous solution of safranin was used as a counter-
stain, provided the slides were weU washed before the application
of the safranin. A heavy precipitate will be deposited on the
smear if the Bismarck brown is not frequently dissolved and
filtered.
The above method has been used for the routine examination
of milk samples for an entire season at a cheese factory where all
grades of milk were being received, and it proved helpful in
eliminating milk which would develop gassy curds. The smears
were checked with duplicate samples stained with methylene
blue and no appreciable difference in the count could be observed.
REFERENCES
Breed, R. S., and Brew, J. D. 1916 Counting bacteria by means of the
microscope. N. Y. Agr. Exp. Sta. Tech. Bui. 49: (Condensed form)
N. Y. Agr. Exp. Sta., Circ. 58.
Conn, H. J., et al. 1919 Methods of pure culture study. Jour. Bact., 4,
107-132.
Hastings, £. G., Evans, Alice E., and Hart, E. B. 1912 The bacteriology
of Cheddar cheese. U. S. Dept. Agr. Bur. An. Ind. Bui. 150.
ijf Bismarck brown stains the background of milk too deeply, slide may be
immersed for a few seconds in a weak aqueous solution of acid fuchsin, after
counter staining.
COLOR STANDARDS FOR THE COLORIMETRIC
MEASUREMENT OF H-ION CONCENTRATION
LOUIS J. GILLESPIE
Conirihuiion from the Reeeiarch Laboratory of Physical Chemistry of the
Massachusetts Institute of Technology ^ No, 1S6
Received for publication December 18, 1920
In an article of the above title recently published in this jour-
nal, Medalia (1920) presents a system of color standards some-
what similar to one published by me a little before (Gillespie,
1920). The work is evidently independent of mine, but the
proposed tables are in serious disagreement with the results of
my work.
The cause of the disagreement apparently does not lie in a con-
flict of observations, but in the plan followed by Medalia in pre-
paring the tables.
It is stated that a test of this plan with the indicator, brom-
thjonol blue, ''succeeded perfectly, i.e., the green color was found
at (pair no. 4) pH 7; or slightly yellowish green at (pair no. 3)
pH 6.8 according to this range. (The change of color of this
indicator was found by the writer to start with pH 6.2 instead of
pH 6 as given by Clark and Lubs.)"
Unfortunately, this test is not suflScient to afford evidence in
favor of the plan as against the method used by me to "smooth
out" experimental errors for the preparation of tables, because
the mass action equation used for this smoothing requires that
such a limited test of the plan shall succeed perfectly, the error
involved being only 0.02 pH, well within the experimental error.
In fact, the mass action equation requires that, if one is able
to determine both limits^ equally distant from the half-transfor-
1 Although there are practical limits to the useful range, there is of course no
real point of pH where the indicator ''starts in" to change color, but only a sub-
jective point ''over the threshold" where it may appear to do so.
399
400 LOUIS J. GILLESPIE
mation point (at pair 4), then pairs 3, 4, and 5 will be substan-
tially correct as calculated by the plan in question, but pairs 2
and 6 will be in error by nearly 0.10 pH, and pairs 1 and 7 by
about 0.25. The mass action equation is, however, in accord
over the useful interval of pH with the measurements of Tizard
(1910) for methyl red, of Bamett and Chapman (1918) for phenol
red,* and pf the present writer for all indicators studied by
Medalia, e^coept the acid range of thjrmol blue, which was not
studied.
We do not need to assume the applicabiUty of the mass action
equation in order to show that the proposed tables are in dis-
agreement with these measurements. It is only necessary to
plot the results to be compared on one diagram in any uniform
manner,' and the discordance will be apparent. The proposed
tables must therefore be considered incorrect, since the plan on
which they are mainly based lacks a solid foundation, and is not
supported by enough data to put into question the conflicting
measurements.
In the article, mention is made of measurement of acid produc-
tion of bacteria by means of pH determinations. A word of
warning seems justified by the fact that the idea is apparent
in the writings of others. The definition of acid production in
terms of a difference between initial and final pH values is decid-
edly not superior to definition in terms of titration, but rather
false, or at least of slender and involved significance. To measure
how much acid is produced we must titrated If the composition of
the culture medium makes impossible a true titration on the
direct culture, then we may distil the volatile acids and titrate
* This has been shown by me (Gillespie, 1020).
*For instance, the percentage of indicator placed in the alkaline solution
may be plotted against the pH pertaining to it, or better, the logarithm of the
ratio between the quantities of indicator as distributed 'between the alkaline
and the acid tubes of the color standards may be plotted against pH. By the
second procedure a straight line is required by the mass action equation. Mathe-
matically, the plan of Medalia consists of a pure guess as to the form of the cunre
obtained by such plotting of the data.
* Measurement of change of pH may, in some cases, give us the acid produc-
tion, if we have already incorporated the results of titration in a titration curve.
MEASUREMENT OF H-ION CONCENTRATION 401
them, or possibly change the composition of the culture medium
(''standard methods" notwithstanding), or resort to even graver
expedients, but the last expedient indeed should be the measure-
ment of pH for the given purpose. Measurement of pH and
titration furnish two distinct methods of attack, each with its
own object and interpretation. The principles involved have
been carefully discussed by Clark and Lubs (1917).
As to a statement to the effect that the electrometric
method is more acciu*ate than the colorimetric, but that the appa-
ratus which it requires is beyond the possibilities of the average
bacteriological laboratory; the writer can subscribe to neither part
in the unqualified form, but would refer again to the article of Clark
and Lubs (1917) for a discussion of the first part, and to the recent
book of Clark (1920) for the second. The writings of Clark
and Lubs also contain full discussions of other principal topics,
such as titration of culture media, effect of bacterial growth
and of sterilization upon the indicators, etc.
It is pleasing to note that Medalia was able to preserve his
color standards. The standards prepared by me were not perma-
nent, and the main difference seems to be in the means taken by
Medalia to avoid microbial decomposition, this point having been
neglected by me.
It seems well to describe in this article, otherwise not very
constructive, an instrument for further study of the indicator
constants and behavior, which was devised too late to be of
service in the work published (Gillespie, 1920). The necessary
improvements in method, for work substantially better than that
already published, must include temperature control of the buffer
solutions in which the indicator is placed, and more precise meas-
urements of the percentage transformation. The apparatus
shown schematically in figure 1 can easily be made to satisfy
both requirements. The writer has not seen it described. It is a
colorimeter for two-colored indicators, and by an obvious modifi-
cation it can be used to determine, if desirable, both the percent-
ages of the two colors present and the total concentration. A
simple apparatus was improvised^ with which the percentages
» In the Laboratories of Soil Fertility, Bureau of Plant Industry, Washington,
D. C.
402
LOUIS J. GILLESPIE
could be determined with far greater ease and precision than is
possible with a one^olored indicator in the usual colorimeter, since
the quality changes very rapidly with the adjustment. Plane
polished surfaces are desirable in the optical system, but were not
used. ■
Th& glass vessels A and C are fixed in position, and B can be
moved up or down, the motion being measured by a pointer
(not shown) fixed to B and moving upon a scale divided into 100
parts. The instrument is so made that the pointer moves from
0 to 100 when B moves from contact with C to contact with A.
The acidified indicator solution of suitable strength may be placed
in B and an alkaline indicator solution of the same strength
Fig, 1, CoLORiMEi
R Two-colored Indicators
placed in C. ^ is left empty.* Then, if the scale reads 70, the
path of light along the left-hand dotted line passes through the
alkaline form during 70 per cent of its path in the indicator, and
through the acid form during 30 per cent. The U^t along the
rightr-hand dotted line traverses an indicator solution m tube E,
again of the same strength, and over a path equal in length to the
* For use in the determination of pH, a tube containing unknown solutioa
without indicator can be slipped into tube A in order to compenBate for color or
turbidity without lengthening the apparatus unduly. In this case, water would
be introduced into D to equal height in order to equaliie absorption uid tb«
MEASUREMENT OF H-ION CONCENTRATION 403
total path on the left. The merit of the mstrmnent consists in
the fact that the length of this total path is not affected by the mo-
tion of tube Bf though the percentages of the path lengths in the
two solutions are varied directly thereby. The indicator solu-
tion in tube E consists of a buffer mixture (or solution, the pH
of which is to be determined) to which the proper amoimt of indi-
cator has been added. If conditions are such that 70 per cent
of the molecides encountered along the path on the right are in
the alkaline modification, and 30, in the acid, then the eye wiU
perceive identical impressions upon looking through the two sys-
tems from above. This will be the case, even if each modifica-
tion is not pure, but admixed with the other, ^ or if each modifica-
tion absorbs to some extent like the other, or if the indicator
exhibits dichromatism. Consequently the apparatus may be used
to determine the apparent percentage transformation of the indi-
cator at different hydrogen-ion exponents; the relation being
studied at different temperatures and subsequently being used
to determine . imknown hydrogen-ion exponents.®
To control the temperature of the buffer solutions or of the
unknown solution, water can be circulated in a jacket (not shown
in the figure) about the tube E. The temperature should be
controlled to about one degree, or possibly better.
It is evident that titrations can be carried out in the tube E,
a proper quantity of strong indicator solution being added for
every cubic centimeter, or smaller unit, of added reagent.
^ It need not be the case if the indicator is grossly coataminated with another
indicator of different apparent dissociation constant, or if the indicator behaves
like a dibasie or polybasic acid. Wegscheider (1915) has made statements
equivalent to those in the text above.
' The instrument can of course be used at once and dependence put for the time
being on the apparent dissociation constants and tables published (Gillespie,
1920). If the indicator used, the temperature, and what information as may be
available as to the salt content of the solution, be recorded, the corrections can
be applied at any time when better values for the indicators and other data are
obtained. Although the writer can not admit that the method previously pub-
lished or the use of a double colorimeter is to be classed as approximate because
of doubtful optical assumptions, it is of course only approximate until precise
calibration of the standards is made. At present the instrimient is capable of
giving more precision than could be obtained in the calibration made without
it, and it may possibly disclose some small deviations from the simple dissociation
curve.
404 LOUIS J. GILLESPIE
It is well known that the snnple law used in ordinary colorim-
etry, namely — the thickness of the solution times the concentra-
tion eqyals a constant when the thickness and concentration are
varied in such a way as to match a standard color — does not hold
for solutions of potassium dichromate. Indeed, with a color
standard of different composition from the solution itself, the
colors shown by a solution of potassium dichromate, as it is
progressively diluted, can not be matched either by dilution of
the color standard or by changing the depth of the layers. On
the other hand, the changing colors can be matched in the double
colorimeter. For standards (in tubes B and C), may be used a
highly acid solution of potassium dichromate, and a solution of
potassiiun (yellow) chromate. As the solution in question is
diluted, it becomes necessary to change the ratio of the path
lengths through the red and the yeUow "forms", as well as to
increase the path length through the solution (in tube E). It
is generally assumed that a change of ionization occurs when
potassium dichromate solution is diluted ; and there seems to be
no reason to doubt that the usual law of absorption holds for the
constibmnts of the solution. There would appear to be no ground
for a suspicion that the "dichromatism" of the sulphone-
phthalein indicators may interfere with their use in the double
colorimeter.
In fact, to derive the law upon which ordinary colorimetry is
based, we assume that light passing through a solution is affected
independently by each particle of colored material, these particles
usually being alike in kind. In order to apply the law to double
colorimetry, we need only the further assumption that the same
is true when the particles are not alike in kind, and it appears
difficult to doubt this in the given case. Consideration of the
expression for the intensity of the emergent light : Ia~, where I
is the intensity of the entering light, a is the fraction absorbed
by each particle, e is the thickness, and o is the concentration of
particles, leads to the following conclusions.*
* The expression is applied to the different wave-lengths entering, the constant
a being assumed different for each wave-length.
MEASUREMENT OF H-ION CONCENTRATION 405
The variation of the constant a with wave-length, which leads
to the dichromatism of the two-colored indicators, does not lead
to any diflSculty in the case of the double colorimeter. Dichro-
matism leads to the detection of errors made when turbidity of
the solution to be measured is balanced optically in the usual
manner. With a one-colored indicator the error made is no less
because of the absence of dichromatism, but the error is not dis-
closed. In routine work, white light is advisable as a source for
comparisons, when it can be used, so that such error may be made
evident by dichromatism. When the subjective difficulties be-
come too great for the use of white light, a screened light (Clark
and Lubs, 1917) may be a valuable means of obtaining an
approximate result.
SUMMARY
The recently published tables of Medalia are in disagreement
with other published data and are not correct.
A colorimeter for two-colored indicators is described for use in
accurate study of the indicators and for the measurement of
hydrogen-ion exponent. The optical assumptions underlying its
use are practically the same as those upon which ordinary col-
orimetry is based.
REFERENCES
Barnbtt, Georqb D.y and Chapman, Herbert S. 1918 Colorimetric deter-
mination of reaction of bacteriologic mediums and other fluids. Jour.
Amer. Med. Assn., 70, 1062.
Clark, W. Mansfield 1020 The Determination of Hydrogen Ions, 318 pp.,
Baltimore.
Clark, William Mansfield, and Lubs, Herbert A. 1917 The colorimetrio
determination of hydrogen-ion concentration and its applications in
bacteriology. Jour. Bact., 2, 1-34, 10^136, 191-236.
Gillespie, Louis J. 1920 Colorimetric determination of hydrogen-ion con-
centration without buffer mixtures, with especial reference to soils.
Soil Science, 9, 115-136.
Medaua, Leon S. 1920 ''Color standards" for the colorimetric measurement
of H-ion concentration pH 1.2 to pH 9.8. Jour. Bact., 6, 441-468.
TizARD, Henrt Thomas 1910 The color changes of methyl orange and methyl
red in acid solution. Jour. Chem. Soc. (London) Trans., 97^ pt. 2,
2477-2490.
Wegscheider, Rud. 1915 Theorie der azidimetrischen Indikatoren. Ztschr.
physik. Chem., 90, 641-680. Especial reference to page 673.
THE EFFECT OF PEPTON UPON THE PRODUCTION
OF TETANUS TOXIN
HARRIET LESLIE WILCOX
Research Laboratoriee, Department of Health, New York City
Received for publication December 19, 1920
Not very long after the outbreak of the European War, labo-
ratory wo Aers realized that a substitute for Witte pepton in bac-
teriological work would have to be obtained. Many labora-
tories were suflSciently stocked with this pepton for the first
twelve to eighteefn months, but in the spring of 1915 it was evi-
dent that the supply of Witte pepton in the United States was
fast dwindling and that it would soon be unobtainable.
WITTE PEPTON
At the Bureau of Laboratories we had been using a Witte pep-
ton glucose veal broth^ with extremely satisfactory results.
Those who have had experience in toxin production, particularly
tetanus toxin, know that from time to time there wiU be marked
variation in toxicity due to some unknown factor or factors.
The same care may be used in the preparation of different lots
of broth as well as in the filtration of the toxin, but the results
may differ widely. In consideration of this fact it may be worth
while to give the different potencies of the toxin made during the
last three to four years when using Witte pepton glucose veal broth.
It is the opinion of some workers that the time of year has a
definite influence upon the production of potent toxin. The
results as given above show that the seasonal factor was of nega-
tive importance as far as toxicity was concerned. If we compare
the quarterly results for the year 1915 we find that the averages
did not vary greatly. The lowest average toxicity of 1:20,000
1 Wilcox, Harriet Lefllie, 1916, Jour, of Bact., 1, 333.
407
JOUBNAL or BACTBBIOLOOT, YOL. VI, NO. 4
408
HABRIET LESLIE WILCOX
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PRODUCTION OF TETANUS TOXIN
409
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410 ' HARRIET LESLIE WILCOX
occurred in the first, third and fourth quarters, while the second
quarter gave an average toxicity of 1 : 27,000.
The differences in the quarterly averages of the year 1916
were so slight that they were scarcely worth mentioning. The
third quarter in this period showed the lowest average toxicity of
1:20,000 while the first, second and fourth quarters gave an
average toxicity of 1 : 22,000.
Doubtless if Witte pepton veal broth had been used throu^-
out the year 1917 we should have had a greater variation in the
quarterly averages, due to the two extremely potent toxins pro-
duced in the third quarter. As far as was known no especial care
was taken in the preparation of these two broths nor in the filtra-
tion of these toxins. In lot 127, the usual procediure of testing
for 1 : 15,000 and 1 : 25,000 was carried out. When the pigs suc-
cumbed in less than forty-eight hours, higher tests, namely
1:40,000 and 1:60,000 were made with similar results. Dilu-
tions of 1:80,000 and 1:100,000 were then injected into guinea
pigs weighing 350 grams each. The pig receiving the 1:80,000
dilution died between the second and third day, while the pig
which received the 1 : 100,000 dilution succumbed on the fourth
day. Since this was the strongest toxin ever obtained at the
Bureau of Laboratories, tests were made of the toxin filtrate to
preclude any possibility of spores or bacilli having passed through
the Berkefeld filter. These tests were negative.
DIFFERENT PEPT0N8
In the spring of 1916, we anticipated the present shortage of
Witte pepton and made comparative tests with some of the
domestic peptons on the market. These results are to be re-
garded as comparative only, but in those that were controlled
by the use of Witte pepton, the differences in the toxicity, with
one or two exceptions, were very significant.
A subsequent test, made with another preparation of Fair-
child pepton, gave a toxicity of only 1 : 8000. No control test
was made as we were unable to obtain Witte pepton.
PRODUCTION OF TETANTT8 TOXIN
411
TABLE 2
Comparative tests of different peptone
TBBlf
TOXXCITT
*
1
Witte (control)
Leitz
Eimer and Amend
1 :25 ,000
1:6,000
1:1,000
1
2
1
Witte (control)
Squibb
Research no. 2
1:25,000
1:5,000
1:15,000
3 {
Witte (control)
Fairchild
1:25,000
1:20,000
i.
Research no. 2
1:20,000
4 1
Witte (control)
Parke, Davis and Company
1:30,000
1:8,000
MARTIN PEPTON
Sporadic attempts at using Martia pepton broth' were made
early in the year 1916 with mdifferent resiilts. Nothing more
was done imtil January, 1917, with regard to the adoption of
Martin broth for tetanus toxin as used at the Pasteur Institute.
The entire absence of Witte pepton at this time prevented us
from making control tests with the usual Witte pepton glucose
veal broth.
The highest average for this period, i.e., in the year 1917,
occurred in the second quarter, when the average toxicity was
1:17,000. The first and third quarters gave respectively the
average toxicity of 1 : 10,000 and 1 : 9000 while the fourth quarter
gave the lowest average toxicity of 1:6,000.
Three different strains of Clostridium tetani were used for a com-
parative test (table 4). The strain designated "Research " is the
culture used in the routine production of tetanus toxin at the
Bureau of Laboratories. This strain was obtained about ten
years ago from the New York State Laboratory at Albany but
its origin and date of isolation are not known. Unless otherwise
> Martin, Louis. Annales de Tlnstitut Pasteur, vol. 12, p. 26, 1897.
412
HARRIET LESLIE WILCOX
TABLES
Martin pepton veal broth
First quarter....^
Second quarter. .
Third quarter. . /
Fourth quarter.'
2 lots 1:15,000
Hot Below 1:5,000
Average toxicity 1 : 10 ,000
Hot 1:25,000
1 lot 1:10,000
Average toxicity 1 : 17 ,000
Hot 1:15,000
2 lots 1:8,000
1 lot 1:5,000
Average toxicity 1:9,000'
Hot 1:15,000
2 lots 1:8,000
3 lots 1:5,000
Slots Below 1:5,000
Average toxicity 1:5,000
1918
2 lots below 1:5,000
Average toxicity below
1:5,000
1 lot below 1:5,000
Average toxicity below
1:5,000
None produced
None produced
TABLE 4
Comparative teste of different strains in Martin pepton veal broth
Experiment 1. December 23, 1916.
Experiment 2. May 19, 1917.
»
Experiment 3. December 15, 1917.
{
8TBAIK8
Research
Goadby
Pasteur
Research
Goadby
Research
Pasteur
Pasteur
TOXICITT
1:35,000
1:35,000
1:25,000
1:10,000
1:15,000
1:8,000
1:8,000
1:8,000
stated this was the strain used in our tests. The Goadby strain
was obtained from Dr. MacConkey, Lister Institute, England,
in 1916, and had been isolated from a war case by Dr. Goadby in
PRODUCTION OF TETANUS TOXIN 413
1915. The Pasteur strain was the one formerly in use at the
Pasteur Institute, Paris, for the production of tetanus toxin.
That this strain did not produce so potent a toxin (1:25,000)
as the Research and Goadby strains (1:35,000) was somewhat
surprising as it had been kept on a mediiun made with Martin
pepton for years, whereas the Goadby and Research strains had
been accustomed to this medium for several months only.
That Martin pepton broth as made by us is capable occasion-
ally of giving potent toxin, is evidenced by the residts obtained
in experiment 1 (table 4) and in experiment 4 (table 5.) The
other preparations of toxin broth were made with the same pre-
cautions and care but, as is shown, with far different results.
When it was apparent that equal parts of Martin pepton and
veal infusion were not giving satisfactory toxin, tests were made
with broth prepared by using more concentrated Martin pepton
solution with ordinary veal infusion (experiment 4, table 5);
also by using the usual amount of Martin pepton solution with
a more highly concentrated veal infusion. In neither case was
the result so satisfactory as with the usual preparation. Sub-
sequent broths were prepared according to the original method,
that is to say using equal parts of infusion and pepton, but the
toxin was far too low in potency to be used.
Word was received in January, 1918, with regard to the modi-
fication of Martin pepton broth used with favorable results for
tetanus toxin at the Pasteur Institute. The variation between
«
this procedure and the one we were using lay in the concentration
of the pepton solution, in the shortened incubation period and also
in the absence of glucose. A preparation of toxin broth (see
experiment 6, table 6) , was made according to this modification,
one-half of the broth having 1 per cent glucose added to it while
the other half was prepared without any sugar. After seven
days incubation instead of the usual period of fifteen days, the
cultures were filtered and tested. The results of the animal tests
were most disappointing as pigs inoculated with 1 cc. of a dilution
of 1:5,000 from each preparation showed an absence of tetanic
symptoms. In his article on the preparation of this pepton,
Martin advises that not less than five stomachs should be used
414
HARRIET LESLIE WILCOX
TABLES
Comparison of different methods for the preparation of Martin pepion veal hrotk
Experiment 4.
June 13, 1917...'
Experiment 5.
October 10,
1917
Experiment 6.
April 2, 1918..
MBDIA
Control broth
1 part Martin pepton solu-
tion (200 grams, of minced
stomach to 1000 cc. H«0)
1 part veal infusion (500
grams of veal to 1000 cc.
H,0)
Experimental broth
1 part of Martin pepton so-
lution
1 part of veal infusion (500
grams of veal to 500 cc.
H,0)
Experimental broth
1 part of Martin pepton so-
lution (400 grams of stom-
ach to 1000 cc. HsO)
1 part of veal infusion
Control broth
1 part Martin pepton
1 part of veal infusion
Experimental broth
1 part of Martin pepton so-
lution
2 parts of veal infusion
Experimental broth
1 pajl of Martin pepton so-
lution (200 grams stomach
to 1500 cc. H,0)
1 part of veal infusion
1 part of Martin pepton so-
lution (300 grams of stom-
ach instead of usual 200
grams to 1000 cc. HjO)
1 part of veal infusion
To the above mixture of
pepton and veal infusion
1 per cent glucose was
added
1 part of Martin pepton
(300 grams of stomach to
1000 cc. HiO)
1 part of veal infusion. No
glucose
0TBAZV
Research
Research
Research
TOXXCITT
1:25,000
1:8,000
Below 1:5,000
Research
Research
Research
Research
Research
1:5,000
1:8,000
1:5.000
Below 1:5,000
Research
Below 1:5,000
PRODUCTION OP TETANUS TOXIN
415
TABLE 6
Bema pepton
1018
1019
m
1020
None produced
1 lot 1:40,000
1 lot 1:35,000
1 lot 1:35,000
1 lot 1:30,000
1 lot 1:30,000
1 lot 1:15,000
Hot 1:25,000
1 lot 1:10,000
1 lot 1:20,000
First quarter. . .<
5 lots 1:15,000
4 lots 1:10,000
•
4 lots 1:8,000
1 lot 1:4,000
Average toxicity
Average toxicity
•
1:15,000
1:22,000
1 lot 1:100,000
1 lot 1:40,000
Hot 1:25,000
1 lot 1: 45,000
4 lots 1:35,000
Hot 1:20,000
1 lot 1:30,000
1 lot 1:5,000
4 lots 1:25,000
Second quarter.
2 lots 1:15,000
1 lot 1:10,000
3 lots 1: 5,000*
1 lot 1: 5,000
Average toxicity
1:21,000
Average toxicity
Excluding* aver-
Average toxicity
1:72,000
age toxicity
1:16,000
1:25,000
r
2 lots 1:8,000
2 lots 1:60,000
1 lot 1:20,000
Third quarter.. <
2 lots 1:5,000
2 lots 1:12,000
Average toxicity
Average toxicity
Average toxicity
i
1:6,500
1:60,000
1:14,000
>
Hot 1:60,000
Hot 1:30,000
Production for this
Hot 1:45,000
Hot 1:20,000
quarter not com-
Hot 1:35,000
1 lot 1:15,000
pleted
Fourth quarter..
Hot 1:25,000
Hot 1:12,000
1 lot 1: 7,000
Average toxicity
Average toxicity
k
1:30,000
1:21,000
* These three lots were grown at too high temperature, i.e., 42*^0.
416 HARRIET LESLIE WILCOX
owing to the great variation of the different stomachs. We are
accustomed to make about fifteen liters of pepton solution for
one preparation of toxin broth. This amount requires seven or
eight stomachs according to the size. At the Pasteur Institute,
marmites or large casseroles holding not less than 60 liters are
employed for the digestion of the pigs' stomachs.
BERNA PEPTON
About this time our attention wa^ called by Dr. Noble of the
New York State Laboratory to a pepton put on the market by
the Swiss Vaccine and Serum Company, of Berne, Switzerland.
The statement that this pepton was made according to Witters
recipe was received with some skepticism but the thought did
occur to us that this might be a means of getting Witte pepton
into the Allied countries.
A small amount of broth (about 15 liters), was made up accord-
ing to our usual method using the "Bema'' pepton instead of
the Witte. So interested were we in the result, that a smaD
amount was withdrawn from one of the flasks, filtered and tested
on the sixth day of growth. The minimum lethal dose was
found to be over 1 : 10,000 after even this short incubation period.
At the end of fifteen days the rest of the cultures were filtered
and tested. The pig which received 1 cc. of a dilution of 1 : 45,000
died of tetanus on the fourth day. A second preparation of
toxin broth made with this pepton yielded a toxin of 1 : 100,000
in potency.
Broth made with Bema pepton has been used at the Bureau
of Laboratories since May, 1918, to the present time with favor-
able results for the production of tetanus toxin (see table 6).
The variations in the quarterly averages were greater than when
_ •
Witte pepton was employed.
The average toxicities as given in this table showed again that
the seasonal factor was of no importance in the production of
potent toxins. The second quarter in the years 1918, 1919 and
1920 gave averages of 1:72,000, 1:21,000 and 1:16,000 respec-
tively. The third quarter of these same years showed still
PRODUCTION OF TETANUS TOXIN 417
greater differences. The average toxicity in this period of 1918
was 1:6,500. In the year 1919 this quarter gave a high aver-
age toxicity of 1 : 60,000 and the same period in the year 1910
showed an average toxicity of 1 : 14,000.
•
SUMMARY
In going over the above results, it will be seen that Witte
pepton has been an important factor in the production of a fairly
constant potent tetanus toxin. The indications are that the
Bema pepton is a satisfactory substitute for Witte since the
latter is no longer available.
It would seem either that the Swiss Serum and Vaccine Com-
pany was justified in its claim that Bema pepton was made
according to Witte formula or that Bema pepton was in reality
Witte pepton since only when using these two peptons did we
obtain a toxicity of 1 : 100,000.
It was a great disappointment that Martin pepton broth as
made by us proved so unreUable. It is just possible that one of
the reasons for the better results with this broth at the Pasteur
Institute, is due to the fact that a larger niunber of stomachs
are used for the preparation of the pepton than we can handle at
one time at the Bureau of Laboratories.
ON THE GROWTH AND THE PROTEOLYTIC ENZYMES
OF CERTAIN ANAEROBES
K. G. DERNBY and J. BLANC
From the Pasteur Inatiiute^ Paris
Received for publication January 7, 1921
In a work that soon will be published oiie of us, Blanc has
extensively studied the biochemistry of certain anaerobes,
especially BociUils aporogenes and Bacillus histolyticus. It seemed
to be of interest also to introduce in that work the methods,
especially worked out in America by Clark and Lubs (1917) and
their followers, for studying the influence of hydrogen ion concen-
tration in its relation to growth and proteolytic activity. The
other of us, Demby, has already in a series of papers used these
methods (Demby 1918, Demby and Avery 1918 and Demby and
David 1920), and as we have limited this paper to as short a
communication as possible, we may for the description of methods
refer to these papers mentioned above. What will follow are
merely the main results of our work with some anaerobic micro-
organisms.
Some time ago, Wolf and Harris and Wolf and Telfer (1917)
studied the biochemistry of the anaerobes, B. welchii {perfringens)
and B. aporogenes (Metchnikoff), taking into consideration the
influence of hydrogen ion concentration. It seems, however,
that they, like many other authors at that time, paid too much
attention to what is called ''the limiting hydrogen ion concen-
tration'' and the influence of organic acids on the growth of the
microorganisms. In bur opinion the first thing to do, when
studying the biochemistry of a given microorganism, is to deter-
mine the limiting and the optunal pH values for the growth of
this organism in a given medium. We by no means claim that
either of these values should be used as a new basis of classifying
419
420 K. G. DERNBT AND J. BLANC
the microorganisms, and especially as to the '^ limiting pH value''
we are very doubtful whether it bears any deciding significance.
The essential thing is to determine the optimum, and, even if this
should change a little under different conditions, to fix such an
initial reaction of the medium as can easily be reproduced and
allow a sufficient growth.
In the first part of this paper we have determined the rela-
tion between growth and hydrogen ion concentration for a cer-
tain nmnber of anaerobes, and in the second part we have studied
the proteolsrtic activity of filtrates from Clostridium sporogenes
and Clostridium histolyticum.
I. THE OPTIMAL HYDROGEN ION CONCENTRATION FOR THE
GROWTH OF SOME ANAEROBES
The following microorganisms have been studied:
Clostridium sporogenes A (Klein-MetchnikoflF)
Clostridium sporogenes 0, isolated from horse excrements
Clostridium canadiense, isolated by Blanc from a case of gangrene
Clostridium histolyticum (Weinberg-Seguin)
Clostridium putrificum (Bienstock).
Clostridium perfringens (Veillon-Zuber)
For all these microorganisms the same broth medium was used.
This was made up in the following way: 1 kgm. finely chopped
veal was immersed in 2 liters of tapwater and allowed to
autolyze at 37® for twenty-four hours; thereafter boiled and
filtered; 0.5 per cent NaCl and 1 per cent pepton added; then
sterilized at 110° for twenty minutes. In preparing an experi-
ment the same amoimt of broth was divided among nine flasks
to which different amounts of HCl or NaOH were added, in order
to obtain certain hydrogen ion concentrations. Table 1 shows
the composition of our nine standard media.
The contents of the nine flasks were then divided up into test
tubes, 10 cc. of the same standard in each, and the test tubes then
sterilized as before. Thus we could always work in a uniform
manner. The tubes were allowed to stand at least for a day at
room temperature in order to obtain a stable hydrogen ion con-
GROWTH OF CERTAIN ANAEROBES
421
centration. All sets of nine tubes, except one intended to serve
as a control for the pH determination, were inoculated with the
same amount of bacterial suspensions. Simultaneously there
were added a few milligrams of solid calcium sulphide powder.
The microorganisms were taken from a twenty-hour pepton-
gelatin cidture. Before inoculation all tubes were heated to
about 37^
TABLE 1
Composition of "Standard*' broth media
30 cc. broth, HCl, NaOH, or H,0, 32 cc.
NUMBBB
N. NaOH
N. HCl
HaO
pH 24 BOtTBfl Arr£B
STRBILIZATION
ce.
oe.
cc.
1
1.8
0.2
3.1
2
1.0
1.0
4.0
3
2.0
4.9
4
0.3
1.7
6.0
5
0.6
1.4
6.5
6
0.9
1.1
7.0
7
1.2
0.8
7.5
8
1.4
0.6
8.0
9
1.8
0.2
8.8
The tubes were placed in an incubator at 37° and after cer-
tain intervals growth was recorded. No microscopic count of
the baciUi was made, the growth was merely estunated, and in
order to be able to reproduce the results graphically we have
indicated the amoxmt of growth by niunbers from 0 to 4. Pre-
liminary experiments indicated that a time of incubation of
from fifteen to twenty hours was the most favorable to determine
the optimal growth.
The initial and the final pH values were determined according
to Clark and Lubs, with the method described in the mentioned
paper by Demby and Avery. All our experiments showed that
under the chosen conditions (see tables 2 and 3) these anaerobes
did not (at least during the first days of incubation) change the
hydrogen ion concentration of the medium to any appreciable
extent. Therefore it was not necessary here as in the case with
pneumococcus or diphtheria bacillus to add any buffers. From
422
K. G. DERKBT AND J. BLANC
many aspects this is undesirable. Already earlier authors have
pointed out that these anaerobes do not change the acidity or
alkalinity of the medium.
TABLES
Chrowth of Clostridium sporogenes 0,
Time of incubation, sixteen hours. Temperature 37*
NUUBBB
pH INITIAL
pH AFTBB 16 HOUBB
DBOBBB or QBOWTB
1
3.1
3.3
Trace
2
4.0
4.0
Trace
3
4.9
5.0
1
4
6.0
6.0
3
5
6.5
6.5
4
6
7.0
7.0
4
7
7.5
7.5
3
8
8.0
7.9
2
. 9
8.8
8.5
0
TABLE 8
Growth of Clostridium histolyticum
Time of incubation, sixteen hours. Temperature, 37*
NUMBBB
pH nrxTiAL
pH AFTBB 16 BOUBS
DBOBBX or OBOim
1
3.1
3.1
0
2
4.0
4.0
0
3
4.9
5.0
0
4
6.0
6.0
2
5
6.5
6.5
3
6
7.0
7.0
4
7
7.6
7.5
4
8
8.0
7.8
3
9
8.8
8.6
0
In tables 2, 3 and 4 some of our experiments are recorded.
Our method, though apparently arbitrary, and giving no ab-
solute basis for the calculation of the rate of growth, yet provides
by the range of comparison which it affords, a quite adequate
standard for all practical purposes.
In figure 1 the results from the tables 2, 3 and 4 are graphically
represented. Even if the point for the optimum pH and the
limits in the different cases change, we may as a whole state that
GROWTH OF CERTAIN ANAEROBES
423
the curves of growth in relation to hydrogen ion concentration
are ahnost identical for all the anaerobes studied. When compar-
ing these curves with those given before for the pneumococcus
and diphtheria bacillus (Demby and Avery, 1918, Demby and
David, 1920), it is obvious that they are much broader, with limits
from pH 5 to pH 9, whereas the limits for the pnemnococcus,
are pH 7 to pH 8.3 and for the diphtheria baciUus pH 5.5 to
pH 8. Obviously the hydrogen ion concentration has much
TABLE 4
Orowih of four types of anaeroSes
Strains used: 1. Clostridium sporogenes A. (Klein-Metchnikoff)
2. Clostridium canadiense
3. Clostridium putrificum (Bienstock)
4. Clostridium perfringens (Veillon iLnd Zuber)
Time of incubation, seventeen hours. Temperature, 37^
pH iKin^L
DBOBSa or OBOWTH
NUMBn
Clostridium
»V€froif€ne$ A
Clottridium
eanadisnn*
ClMlriiium
putrificum
Clostridium
perfrinQtns
1
3.1
0
0
. 0
0
2
.4.0
0
0
0
0
3
4.0
Trace
0
Trace
Trace
4
6.0
2
2
1
1
5
6.5
4
3
4
3
6
7.0
4
4
4
4
7
7.5
3
3
4
4
8
8.0
2
1
3
3i
9
8.8
0
0
1
1
less influence — ^within certain limits — on the growth of these
anaerobes than on the growth of, e.g., the pneumococcus.
The optimum for all of the microorganisms studied here seems
to fall between pH 6.5 and pH 7.5. If any distinction shoidd
be made it might be said that Clostridium sporogenes seems to
have an optimum a little less than pH 7 and the others a little
more than pH 7. That indicates that these microorganisms
grow most favorably in media which have a neutral reaction,
that is pH 7.
424
E. O. DERNBT AND J. BLANC
GROWTH OF CERTAIN ANAEROBES 425
II. THE PROTEOLYTIC ACTIVITY OP FILTRATES FROM CLOSTRIDIUM
SPOROGENES AND CLOSTRIDIUM HISTOLYTICUM
It is well known that anaerobes of this type are strongly pro-
teolytic, dissolve fibrin and casein, liquefy gelatin, disintegrate
pepton, and so on. The present mode of classifymg the pro-
teolytic enzymes seems to be to determine (1) the substrates
attacked, (2) the products of digestioh and (3) the optimal hydro-
gen ion concentration for the action. The two best substrates,
which can be used in solution, are gelatin and pepton. In the cited
paper by Demby (1918) the method for using these substrates
is fuUy described. Below we have studied the proteolytic
activity of Clostridium sporogenes and Clostridium histolyticum.
As enzyme the broth culture after passing a Chamberland
filter has been Used. By this method, we of course get in-
formation only in regard to the ''ekto" enzymes, whereas the
"endo" enzymes will escape our attention. The ideal thing
would be to obtain large quantities of the bacilli, let them auto-
lyze and determine the proteolytic activity of the autolysate.
It is possible that in that case we should obtain enzjnnes both
of the pepsin and of the trypsin-erepsin group as has been found
is the case of yeast (Demby, 1917).
The filtrates were obtained in the following way : For each cul-
ture 500 cc. of an ordinary broth made from autolyzed veal was
taken, 1 per cent glucose and enough NaOH to render the initial
reaction almost neutral (pH 7) were added. The mixture was
sterilized at 107° for an hour. After cooling to 37° the flasks
were inoculated with the microorganism in question, and simul-
taneously a minimal dose of soUd calcium sulphide was added.
The flasks were allowed to stand in the incubator at 37° for
seventy-two hours, and then 3 cc. of chloroform were added. The
culture was first filtered through paper and thereafter passed
through a Chamberland filter. The clear filtrate was kept sterile
at room temperature, and exhibited strong proteolytic activity
for several months.
426
K, G. DERNBY AND J. BLANC
Gelatin tests
In order to make all experiments in exactly the same manner
standard mixtures of gelatin and HCl or NaOH were made before-
hand, of which the hydrogen ion concentrations were known.
Table 5 shows the composition of these, mixtures.
As our aim was to study the optimum reaction, it was suf-
ficient for us to study the first stages in the liquefaction process.
During this early period the hydrogen ion concentration will
not change much, and buffers could be omitted.
TABLE 6
Composition of gelatin mixtures
The gelatin solution contained 14 per cent gelatin and 0.4 per cent thymol.
10 cc. gelatin, HCl, NaOH or HsO, 12 cc.
N171IBBR
N.
Ha
N.
NaOH
HiO
pH
•
ce.
ee.
ee.
1
1.0
.1.0
3.0
2
0.2
1.8
4.0
3
2.0
4.8
4
0.04
1.96
5.5
5
0.1
1.9
6.3
6
0.2
1.8
7.0
7
0.3
1.7
8.3
In preliminary experiments it was determined how much of
the enzyme had to be taken m order to liquefy the gelatin within
4 to 20 hours at the optimum pH value 6.5.
In all cases a set of seven tubes was used, covering a range in
pH from 3.0 to 9.0. Ordinarily 6 cc. gelatin were used for each test.
The tubes were warmed to 37® before the enzyme was added.
The gelatin contained 0.5 per cent thymol and the enzyme solu-
tion was aseptic. Therefore hardly any proteolytic activity from
other microorganisms need be taken into consideration during the
short time of digestion. A blank experiment was always run at
the same time. After certain intervals the tubes were taken
from the incubator and put into an ice bath for exactly ten min-
utes; thereafter the degree of liquefaction was estimated by the
method given in the paper by Demby (1918).
GROWTH OF CERTAIN ANAEROBES
427
In figure 2 the results are graphically represented. The re-
sults from the tables 6 and 7 are almost similar. In both cases
there is a marked proteolytic activity between pH 4 and pH 8,
and the optimum is in both cases near pH 6. When allowed
TABLES
Cloairidium aporogenes on geUUin
Filtrate from Clostridium aporogenes A. Klein-Metchnikoff. , Temperature, 37***
6 CO. gelatin, 0.5 cc. filtrate
NTTIIBBB
DBORCV or LIQUKTACnON AmCB
3 hours
Ohoun
20houn
1
2
3
4
5
6
7
•
3.0
4.0
4.8
6.5
6.3
7.0
8.3
0
0
0
1
2
1
0
0
0
i
1
3
2
0
0
1
2
5
6
3
1
TABLE 7
Clostridium histolyticum on gelatin
Filtrate from Clostridium histolyticum Weinberg and Seguin. Temperature, 37'
6 cc. gelatin, 0.5 cc. filtrate
DBQBBB or LIQDSrACnON AFTBB
milCBBB
pH INITIAL
2 hours
4 hours
20 hours
1
3.0
0
0
0
2
4.0
0
0
0
3
4.8
1
li
4
4
5.5
2
4
6
5
0.3
11
3i
6
6
7.0
0
1
5
7
8.3
0
1
5
to digest for a long period of time all tubes except the most acid
ones are liquefied.
We seem justified in stating that in the filtrates from these
two microorganisms enzymes resembling trypsin are present.
428
K. G. DERNBT AND J. BLANC
Pepton teat
Table 8 shows the composition of the pepton standard so-
lutions. The rate of digestion was measured with the Sorensen
formol method. Tables 9 and 10 give the results of experiments
with Cloetridium aporogenea and Cloatridium hiatolyticum.
It may be objected that in this case the Van Slyke method
might have given sharper values, but the only question we wanted
to study was the optimum for the action of the enzymes on pep-
ton, and for this purpose the formol method gives results which
Flg.£.
C- A/sfo/yT/cont
can not be misinterpreted. In figiu^ 2 the results are graphi-
cally represented. It is evident that the enzymes from dos-
Iridium aporogenea act in the same manner as to the pH optimum
as those from Cloatridium hiatolyticum. For both the optimum
is at pH 6 and the range within which they act is pH 4 to
pH 8. Also in this case the enzymes acting on pepton seem to be
"tryptases.''
From figure 2 it is evident that the action on gelatin and the
action on pepton of the two anaerobes in relation to the hydrogen
GROWTH OF CERTAIN ANAEROBES
429
TABLE 8
CompoaUion of peptan mixtures
10 cc. 4 per cent pepton solution, NaOH, HCl or HtO, 40 cc.
toluene added
Chloroform and
NTJMBBB
N.
NaOH
N.
HCl
•
PH
oe.
ee.
1
0.6
3.0
2
0.1
4.0
3
4.7
4
0.04
5.5
5
0.08
6.2
6
0.2
7.1
7
0.3
•
7.7
8
0.5
8.5
TABLE 9
Clostridium sporogenes A, on pepton
10 cc. pepton, 0.5 co. filtrate. Temperature, 37°. Time of digestion, seventeen
hours
NUIIBBB
pH iirmAL
LIBERATBD AMIITO-N IN 10 OC.
AFTBB 17 HOUB8
•
Bl^lft.
1
3.0
0
2
4.0
0.1
3
4.7
0.55
4
5.5
0.65
5
6.2
1.0
6
7.1
0.65
7
7.7
0.4
8
8.5
0
TABLE 10
Clostridium histolyticum on pepton
10 cc. pepton, 0.5 cc. filtrate. Temperature, 37°. Time of digestion, seventeen
hours
KDMBBB
pH INITIAL
LIBRRATED AUINO-N IN 10 CC.
AFTER 17 HOOBS
mom.
1
3.0
0
2
4.0
0.2
3
4.7
0.7
4
5.5
1.05
•
5
6.2
1.95.
6
7.1
1.1
7
7.7
0.3
8
8.5
0
430 K. O. DERNBT AND J. BLANC
ion concentration are almost identical. Whether it is the same
tryptase that acts in both cases, or whether there are several
is impossible to say.
The conclusion we have arrived at by these experiments is
simply that the proteolytic enzymes in filtrates from Clostridium
sporogenes and Chsbridium histolyticum seem to be veiy much
alike, and that the enzymes which can be detected belong to the
tryptase group.
It must be remembered however that in the living or dead
microorganisms there are also present proteolytic enzymes of
other types.
SUMMARY
The optimal and limiting hydrogen ion concentrations for the
growth of the anaerobes, Clostridium sporogenes^ Clostridium
histolytibum, Clostridium canadiense, Clostridium putrificum and
Clostridium perfringens have been determined. The range in
which all of these organisms live has the limits pH 5 to pH 9.
The optimum range for all seems to be at or about the neutral
point pH 7 and is apparently a rather broad one.
2. The proteolytic activity of filtrates from Clostridium sporo-
genes and Clostridium histolyticum has been studied. Gelatin
is liquefied and pepton is disintegrated in the range pH 4 to pH 8,
and the optimum for both these reactions seems to be about
pH 6. The conclusion is that in the filtrates a tryptase is present
REFERENCES
Clark, W. M., and Lubs, H. A. 1917 Jour. Bact., 2, 1.
Dernby, K. G. 1917 Biochem. Z., 81, 109.
Dbrnby, K. G. 1918 Jour. Biol. Chem., 80, 179.
Dernbt, K. G., and Avert, O. T. 1918 Jour. Exp. Med., 28, 345.
Dernbt, K. G., and David, H.: 1920.
Wolf, Ch. G., and Harris, J. 1917 Jour. Path, and Bact., 21, 385, and Bio-
chem. Jour., 11, 213.
Wolf, Ch. G., and Telfer, S. V. 1917 Biochem. Jour., 11, 297.
THE MANNITOL-PRODUCING ORGANISMS IN SILAGE
G. p. PLAI8ANCE and B. W. HAMMER
From the Bacteriology and Dairy Sections of the Iowa AgricvlturaX Experiment
Station
Received for publication December 27, 1920
INTRODUCTION
. The chemistry section of the Iowa agricultural experiment
station has shown (Dox and Plaisance, 1917 a and b) that manni-
tol is a normal constituent of silage and has reported experiments
indicating that ^4t is formed in silage fermentation by bacterial
reduction of the fructose-half of the sucrose molecule.'' In
silage, the mannitol is produced in considerable amounts, simul-
taneously with the acids, the carbon dioxide and the alcohol
and '4ts presence accounts in large measiire for the deficit noted
when the sum of these products is balanced with the fermented
sugar. "
The results reported in the present paper* deal with the isola-
tion from silage of organisms capable of producing mannitol
when grown in pure cultures in corn, corn juice, and various
other materials.
HISTORICAL
The presence of mannitol in the higher plants, in both the
higher and lower fimgi, and in various fermented materials
such as wine, vinegar and sauerkraut, as well as its production
by organisms, has already been dealt with in some little detail
in the publications of the Iowa station. It is evident that
mannitol fermentation has long been known and that it is more
or less common.
*
^ The work herein dealt with was carried out in 1917 and was to have been
reported at the meeting of the American Society of Bacteriologists in that year.
The National Research Council, however, requested that the report be delayed
because of the possible use of mannitol in the manufacture of explosives.
431
JOUBNAL or BACrXBIOLOOT, VOL. TI, NO. fi
432 G. P. PLAISANCE AND B. W. HAMICEB
METHODS USED
Id order to prevent repetition, some of the materials used
are here described. The com juice was secured by pressing
green com, while the stover juice was obtained by soaking com
stover in water for twelve hours and then pressing. The com
silos were made by packing chopped green com, and the stover
silos by packing chopped stover, and adding a calculated amount
of water and usually about 5 per cent sucrose, calculated on a
dry basis. For most of the silos, the material was packed in
quart Mason jars but in a few instances bottles or flasks holding
from 1 to 2 liters were used.
Corn juice agar was made by adding 1.5 per cent agar and
1 per cent pepton to the corn juice while the stover juice agar
was made by adding 1.5 per cent agar, 1 per cent pepton and
5 per cent sucrose to the stover juice; the stover juice agar was
commonly cleared with an egg when it was wanted for plating
but this was not necessary with the com juice agar. The com
juice agar was more satisfactory than the stover juice agar
because it was lighter in color and apparently gave a more
satisfactory growth.
The method of isolating and determining mannitol in silage
was that used in the former work at the Iowa station which has
already been referred to. Mannitol was determined in liquid
cultures by evaporating 100 cc. aliquot to dryness on a steam
box; the residue was then extracted five times with boiling 95
per cent alcohol (about 15 cc. of alcohol in each portion) and
the combined extracts filtered as soon as cold. After standing
over night the mannitol had crystallized; the crystals were
sucked dry, recrystallized from water and alcohol, dried and then
Weighed.
RESULTS SECURED
The rdle of microSrganisms in mannitol jyrodudion
Although in the previous work at the Iowa station the pro-
duction of mannitol was secured by inoculating sterilized stover
(plus sucrose and water) with a decoction of a leaf of cotu silage.
MANNITOL-PRODXJCING ORGANISMS IN SILAGE
433
and was not secured in ''antiseptic" silage made by adding ether
to corn, it seemed desirable to repeat and extend these experi-
ments in order to confirm the relationship of organisms to
mannitol production. The inoculation of sterilized com or
stover silos with a bit of normal silage gave mannitol production
regularly. The lack of mannitol in corn silos treated with
various chemicals and held at room temperature for periods
that gave mannitol with the untreated corn is shown in table 1.
When silage from the silos to which the various chemicals
had been added was examined under the microscope a very few
lightly stained bacteria were the only microorganisms observed
and these, in all probability, represented organisms that were
TABLE 1
The influence of various chemicola on mannitol production , room temperature
incubation
ADOBO TO THB COBN
Nothing added, normal fennentation
Ether
Chlorofoim
Chloroform and toluol
Formaldehyde
PERIOD or
BOLDIMQ
MANNITOL
4tt}f9
Present
None
None
None
None
present on the corn at the time the silos were filled. The normal
silage on the other hand showed very large numbers of well
stained bacterial and yeast cells and thus presented a very dif-
ferent pictiu'e than the treated silage. When these statements
are compared with table 1 it is evident that when microorganisms
developed normally mannitol was produced, while when the
growth of microorganisms was prevented by various chemicals
no mannitol was formed.
The isolation of mannitoUproditcing organisms
The isolation of organisms capable of producing mannitol was
attempted by plating out samples of silage on corn juice or
stover juice agar. Representative organisms developing on
the plates were grown on agar slopes (usually the same agar as
434 O. p. FLAISANCE AND B. W. HAMMER
that used for plating) and were then tested for mannitol-pro-
ducing power by inoculating into sterile com juice, sterile stover
juice, a sterile com silo or a sterile stover silo, allowing growth
to go on for a period varying from a few days to several weeks,
and then examining the material for mannltol.
Attempts were made to isolate mannitol-producing organisms
from a number of samples of silage that had been ensiled several
months but only negative results were secured. Yeast* colonies
were commonly present on the plates in considerable mmibers
and often made up the greater part of the developing flora;
many of these were tried out for mannitol-producing power but
when the yeasts were in pure culture mannitol was never found.
Other types of silage were then studied and the first mannitol-
producing organism isolated — M39 — was secured from silage
fourteen days old that was made by ensiling green com from the
greenhouse; the silage contained 1.09 per cent mannitol at the
time it was plated out. The colony from which M39 was secured
was very small and comparatively few of its kind were present;
the organism was found capable of producing mannitol in sterile
com juice, in sterile stover juice, in sterile com silos, and in
sterile stover sucrose silos and has consistently given mannitol
in a large niunber of trials.
Mannitol-producing organisms were readily isolated from a
sample of com juice that was covered with oil (to keep down
mold growth) and allowed to ferment spontaneously and that
showed, after a short period, considerable quantities of mannitoL
A dirbct microscopic examination showed many yeast cells and
still larger niunbers of bacteria. On plating out, on corn juice
agar, material from both the upper and lower layers of this fer-
menting juice, colonies similar to those of M39 were found in
large numbers, together with many yeast colonies. When the
colonies similar to those of M39 were streaked on agar slopes
and then inoculated into either sterile com juice or a sterile
silo, mannitol was found in considerable amounts after the usual
holding period.
' The term yeast is used to indicate organisms reproducing by budding.
MANNITOL-PRODUCING ORGANISMS IN SILAGE 435
Evidence that organisms of the tjrpe of M39 are concerned in
the production of mannitol was furnished unexpectedly in two
instances as follows:
1. A control stover silo, which had been opened after steri-
lization only for the purpose of adding sterile water, contained
considerable mannitol when it was examined after a period of
about two weeks. Microscopic examination showed many
organisms morphologically resembling M39 and com juice
agar plates inoculated with the material yielded colonies like
those of M39; transfers 'were made to com juice agar and when
the organisms were inoculated back into the usual test materials
mannitol was found in considerable quantities after a holding
period of from ten to twenty days. It seems that the presence
of the mannitol-producing organisms in the silo was due to
accidental inoculation since the organism is not exceptionally
heat resistant and accordingly would not be expected to survive
the heating during sterilization; moreover the other control
showed neither organisms nor mannitol.
2. One of the yeasts isolated from silage was inoculated into
a sterile stover silo and after the usual holding period an exami-
nation showed the presence of mannitol. When the silage was
examined microscopically, in addition to the yeast, an organism
morphologically similar to M39 was found in large numbers;
this organism was isolated by plating on corn juice agar and
proved capable of producing mannitol when inoculated into the
usual test materials. Although a microscopic examination of
the original yeast culture had shown no bacteria, it is entirely
possible that a very small number of organisms of the M39
type may have been present in the culture and had thus been
inoculated into the silo along with the yeast. Contamination
of the silo, either at the time of inoculation or later when the
silo was opened to release pressure, is another means of explain-
ing the results secured.
Influence of oil at the surface of the liquid on mannitol ^production
Since the formation of mannitol is to be looked upon as a re-
ducing process, it was thought that the addition of sterilized
436
O. p. PLAISANCE AND B. W. HAMMWK
oil to the flasks of liquids to be fermented might materially
modify the restdts obtained. A number of comparisons of
oiled and unoiled material were made at room temperature,
using a juice expressed from cane and to which 2 per cent sucrose
had been added before sterilization; the results secured are
presented in table 2. From the data given it is evident that
under the conditions employed, a larger percentage of mannitol
was secured with oil than without it. Because of the gas liber-
ated, which probably drives ofif much of the unconsumed oxygen,
the conditions in the unoiled flasks must be, to a certain extent,
anaerobic and this, in all probability, explains the formation of
mannitol in the absence of oil. Whether the presence of air
results in a smaller production of mannitol or in a destruction
TABLES
The influence of oil on manniUil production, room temperature incubation
OBOANIBM
PKBIOO or nfCTTBATION
PKB CKNT OP MANNITOL
Without oil
With oU
M30
M363
M308
M439
M283
12
12
12
12
12
1.58
0.60
Trace
0.44
0.46
1.75
0.83
1.79
1.60
0.71
of a portion of that produced is impossible to determine from the
data available.
In general, during the fermentation of the juices used there
was a pronounced change in color; in the unoiled flasks the lighter
portion involved mainly the lower depths, due presumably to the
air above, while in the oiled flasks practically the entire liquid was
involved. It seems probable that the change in color involved
a reduction of some indicator present in the fermenting juice^
the process being essentially similar to the reduction of litmus
by many organisms, although it is possible that the change in
color was due to the production of acid; the latter explanation
is less acceptable than the former since the change in color in
general agrees with the state of anaerobiosis.
MANNTIOL-^RODUCING ORGANISMS IN 8ILAGS 437
Materials yielding mannitol
The organisms that were found capable of producmg mann tol
in the usual test preparations were studied as to their ability
to produce it in a number of other materials. Two cultures
from different samples of silage were inoculated into sterilized
carrot juice' but no mannitol was secured. Both table and
sugar beet juices were tried, two cultures on the former and
four on the latter, but with negative results. Cabbage juice
gave considerable quantities of mannitol with each of the three
organisms inoculated into it and in general there was abundant
gas formation. With the juices of the carrot, beet and cabbage
there was a change in color similar to that secured with the com
and stover juices and in all cases the turbidity which developed
indicated that the organisms were growing well. The f ailiu'e to
secure the production of appreciable amoimts of mannitol with
carrot and beet juice was undoubtedly due to the lack of
the proper carbohydrate materials in them. A considerable
number of flasks of apple juice were sterilized and inoculated
with diflferent cultures but there was no evidence of growth in
any of them and the few flasks examined showed no mannitol;
the same results were secured when the apple juice was neutral-
ized before sterilization. Considerable quantities of mannitol
were secured when sunflower stalks, leaves and blossoms were
chopped, packed in jars, sterilized and inoculated with pure
cultures of diflferent mannitol-producing organisms, or when the
sunflower material was packed in jars and allowed to ferment
spontaneously. Cane yielded considerable quantities of manni-
tol when treated similarly to the sunflowers, as did also mixtures
of stems, leaves and blossoms of dandeUons.
One lot of stover juice (juice x) was found to contain only
very small amoimts of hexose sugars and accordingly it was
used as a basis for testing out various materials. When 5 per
cent cane sugar was added to this juice and the material steri-
lized, tests showed no appreciable inversion of the sugar; on
inoculation with some of the mannitol-producing organisms
' The various juices were secured with a powerful press.
438 O. p. PLAISANCB AND B. W. HAMMER
only traces of mannitol were found and it seems probable that
this came from the small amounts of hexose sugars present
in the juice. In the light of these tests it seems difficult to
explain the value of the cane sugar in the stover juice, stover
silos, etc.; it is entirely possible, however, that inversion might
have occurred in some cases, even if not with juice x. By the
addition of 5 per cent invert sugar to juice x, sterilization,
and the inoculation of mannitol-producing organisms consid-
erable quantities of mannitol were secured; growth was appar-
ently very rapid and there was usually a pronoimced change in
color and the evolution of considerable gas. When honey
(usually 8 per cent was used) was added to juice x, there was
TABLES
' Mannitol in silage made from stover plus various substances, room temperature
incubation
' MATBRIAL ADDED TO STOVER
KAWirnoL
Glycerol
pm-cmt
0
Galactose
0
Glucose
0
Fructose
3.71
Maltose
0
Lactose
0
Inulin r
0.40
Starch
•
0
an exceptionally heavy gas production, a pronoimced change in
color and the formation of considerable quantities of mannitol
A series of silos was made by cutting up corn stover (con-
taining practically no sugars) adding various substances, pack-
ing in Mason jars and then sterilizing, after which organism
M39 was inoculated. The results of mannitol determinations
made on the silage after a suitable holding period at room
temperatiu'e are shown in table 3. From the data presented
it is evident that fructose and inulin jrielded mannitol while
glycerol, galactose, glucose, maltose, lactose and starch did not.
Many lots of silage made by inoculating various organisms
into sterilized stover plus sucrose have, as already stated, yielded
mannitol.
MANNITOL-PRODUCINO ORGANISMS IN SILAGE 439
It seems then that only fructose, or materials giving fructose
on hydrolysis were capable of yielding mannitol when acted on
by the mannitol-producing organisms studied. The small
amount of mannitol produced in the inulin stover silo, as well
as in many of the sucrose stover silos, was undoubtedly due
to the inability of the organisms to hydrolyze these materials
and to the small amoimt of hydrolysis which occurred during the
process of sterilization. The variations in the amounts of
iriannitol produced in the sucrose stover silos were very likely
due to differences in the amount of hydrolysis, and this was
materially influenced by the amount of acid present and by the
extent of the heating. Gayon and Dubourg (1894; 1901)
found that only fructose or its moiety jrielded mannitol and
Brown has shown how the configuration of fructose is such that
it alone can be changed to mannitol by organisms.
It is entirely possible that certain organisms may be able to
produce mannitol from such materials as sucrose and some
results have been secured which indicate that one of the cultures
isolated is able to do this. It seems quite certain, however,
from results secured with the use of bouillon to which sucrose
was added, that most of the cultures isolated are unable to
change sucrose to mannitol.
IXatribiUion of the TnanniioUprodiunng organisms
Since mannitol is a normal silage constituent and is produced
by the action of microorganisms, it would be expected that
mannitol-producing organisms would be rather widely distrib-
uted about barns where silage is used, due to the scattering of
silage and of manure from animals consuming silage. A number
of materials have been tested for mannitol-producing organisms
by inoculating them into sterile com juice, flooding the juice with
sterile oil in order to keep down the growth of molds and then
determining the presence or absence of mannitol after a suitable
incubation period at room temperature. The production of
mannitol has been secured with soil from a farm yard and also
with milk, but the trials made are too few in number to allow
of any conclusions regarding the extent of the contamination
of these materials.
440
G. P. FLAISANCE AND B. W. HAMMBR
The per cent of mannitol produced in various materials
The per cent of mannitol produced in different materials varied
widely. While this was due to a large extent to variations in
the per cent of total sugar, as well as to variations in the nmke-up
of the sugar in the original materials, differences in the efficiency
of the different organisms tried undoubtedly played a very large
part. Table 4 presents data, other than those already presented,
showing the per cent of mannitol produced under different con-
ditions and in various materials. Many other determinations
were made only to find out whether mannitol was present in
traces or in considerable quantities and the results are of course
omitted.
TABLE 4
The per cent of mannUol produced under different conditions, room temperature
incubation
MATSRXAI.
Cane juice plus 2 per cent sucrose
Cane juice plus 2 per cent sucrose
Cane juice plus 2 per cent sucrose
Cane juice plus 2 per cent sucrose
Cane juice plus 2 per cent sucrose
Cane juice plus 2 per cent sucrose
Green com silage
Com juice
Com juice
INOCULATION
PERIOD or
BOLDINO
'•V*
ptrenU
M283 plus yeast
12
1.85
M2{3 plus yeast
12
1.05
Md08 plus yeast
12
1.65
M308 plus yeast
12
1.00
M439
12
0.49
M308
12
0.52
M39
18
0.59
M393
12
o.eo
M393
20
0.92
The destruction of mannitol
The data already reported by the Iowa station show that, m
a silo, part of the mannitol produced is destroyed. Table 5
shows the per cent of mannitol present at various times in stover
silage containing sucrose inoculated with organism M39 and
held at room temperature. A series of silos were prepared and
a different one used for each determination.
From table 5 it seems that, at least with the organism used, the
production of mannitol was accompanied or followed by its
partial destruction.
MANNITOI/-FROPTJCING ORGANISMS IN SILAGE 441
Organisms having mannitoUproducing powers
A considerable number of organisms capable of producing
mannitol were isolated from various samples of silage and
studied morphologically, culturally, and biochemically. The
results shoyred that the organisms cannot be considered to be
of one t3rpe. Most of the cultures isolated produced no appre-
ciable change in milk and undoubtedly should be classed as
BadUus manniticus of Gayon and Dubourg, but one of the
cultures in particular produced a coagulation in litmus milk
with an extensive reduction of the Utmus and its general charac-
teristics indicated that it should be classed as Bad. ca^ei. Cer-
tain of the rod-shaped (Kruse 1910; Orla-Jensen 1919) lactic acid
TABLE 5
The per cent of mannitol at various times in stover silage containing sucrose and
inoculated with organism MSB, room temperature incubation
PBBIOD Oy BOLDINO
•
MAKMtTOI.
iapB
ptreent
6
1.41
8
2.41
10
2.63
12
1.60
14
1.54
•
20
1.38
organisms have been shown by a number of investigators to
produce mannitol. With this group of organisms, however,
mannitol production is not a general characteristic since a con-
siderable number of cultures from sources such as milk, silage
and cow feces were examined for mannitol production by inocu-
lating into satisfactory media but only with negative results.
From the findings reported it seems that the production of
mannitol in silage is not the result of the action of organisms
present in silage alone but is brought about by the activity
of organisms that have been shown to produce mannitol in other
materials such as wines, etc. The conditions, such as a lack of
oxygen and the presence of sugar, existing in silage during the
period of active fermentation are undoubtedly very favorable
442 G. p. PLAISANCS AND B. W. HAMMER
to the type of change resulting in the formation of mannitol
from fructose. The rod-shaped lactic acid organisms constitute
a group that is present in silage in enormous nimibers (Hunter
and Bushnell, 1916; Sherman, 1916) and while many of these
do not produce mannitol it seems probable that mannitol-
producing forms may be expected among them.
CONCLUSIONS
1. The production of mannitol in silage is very evidently
due to bacterial action.
2. Mannitol-producing organisms were readily isolated from
silage, provided it had been ensiled recently. They were also
secured from a sample of fermenting corn juice.
3. In liquids, more mannitol was produced when they were
flooded with oil than when they were not.
4. Mannitol was produced, by the organisms isolated, in
the juice of cabbage and in silage made from com, sunflowers,
cane or dandelions, but not in the juice of carrots, beets, or
apples. Fructose, or materials giving fructose on hydrolysis, such
as sucrose or inulin, also yielded mannitol when added to stover
before sterilization; it is probable that the hydrolysis was due to
the heating and the acid present and cannot be accomplished
by the organisms although there may be variations among the
organisms in this respect. Glycerol, galactose, glucose, maltose,
lactose and starch did not yield mannitol when added to stover
before sterilization while honey gave large amounts.
6. The mannitol-producing organisms were found to be pre-
sent in soil from a farm yard and in milk.
6. The percent of mannitol produced in different materials
varied widely, due undoubtedly to a large extent to variations
in the types and amounts of sugar present.
7., With the only organism that was tried, the production
of mannitol was accompanied or followed by its partial
destruction.
8. The organisms producing the mannitol in silage cannot
be considered to be of one type.
MANNITOL-PRODUCING ORGANISMS IN SILAGE 443
REFEKENCES
Dox, Abthub W.y AND Plaibakcb, G. p. 1017a The occurrence and significance
of mannitol in silage. Jour. Am. Chem. Soc, 39, 2078.
Dox, Abthub W., and Plaisance, G. P. 1917b The occurrence and significance
of mannitol in silage. la. Agr. Exper. Sta. Res. Bui. 42.
Gaton, TJ., and Duboubo, E. 1894 and 1901 Sur les Vins Mannit^s. Ann.
Inst. Pasteur., 8, 108; and Nouvelles Recherches sur le Ferment Manni-
tique. Ann. Inst. Pasteur., 16, 527.
HxTNTBB, O. W., AND BusHNELL, L. D. 1916 The importance of Bacterium
brdgarieua group in ensilage. Science, n.s., 4S, 318.
Kbube, W. 1910 AUgemeine Mikrobiologie, p. 401.
Obla-Jbnbsn, S. 1919 The lactic acid bacteria. M6moires de TAcad^mie
Roy ale des Sciences et des Lettres de Danemark. Section des Sciences,
8°* s^rie, 6, no. 2.
Shebman, Jaioss M. 1916 A contribution to the bacteriology of silage. Jour.
Bact., 1, 445.
PRINCIPLES CONCERNING THE ISOLATION OF
ANAEROBES
STUDIES IN PATHOGENIC ANAEROBES. II
HILDA HEMPL HELLER
From the George Williams Hooper Foundation for Medical Research, Universiiy of
California Medical School, San Francisco
Received for publication December 30, 1920
The subject of the isolation of anaerobes is one which the worker
is inclined to approach with apologies. Every month or so a
paper appears in some journal in which a new and expeditious
procedure for the separation of anaerobes is described. There
are many successful ways of isolating anaerobes and it is unwise
to recommend any one method above aU others. I have succeeded
with various arrangements; and wish in this paper to analyze
some of the principles governing the isolation of these organisms
and to explain a few of the pitfalls which have caused many
workers to believe that the securing of "absolutely pure" anae-
robic cultures is a difficult matter. With a little practice and with
the exercise of much discrimination, anaerobes may be isolated
as quickly, or nearly as quickly, as aerobes.
Contamination occurs somewhat more frequently in anaerobic
cultures than in those of aerobes. Contamination of originally
pure cultures may be attributed to the following causes: (1) In-
sufficiently sterilized media; anaerobe media are usually pasty
and require more careful sterilization than others. (2) Inocu-
lation transfer involving the exposure of the cotton plug and of
the inoculmn to the air. I have noted in working in London and
near the sea in San Francisco, that the more dusty the air, the
more frequent are contaminations, and the contamination
flora may vary according to location. (3) During incubation in
closed jars the cotton plugs may become sufficiently moist for
445
446 HILDA HEMPL HELLER
molds to grow through them; where a mold can grow a bacillus
can follow. (4) During prolonged incubation water of con-
densation may even run into the tubes from the top of the jar.
(5) If stored in closed cans molds may grow through the plugs.
Workers should take these points into consideration in planning
their work. Anaerobic jars are exceedingly convenient and prac-
tical for periods of incubation under four or five days, and for
much anaerobic study twenty-four to forty-eight hours incubation
is stifficient. Prolonged incubation should be made imder vase-
line or in the case of sugar-free media in exhausted sealed tubes.
Sealing of tubes is inadvisable where carbon-dioxide may be so
confined that it produces an acid end-point. Re-incubation of
cultures in exhaust jars should be cautiously undertaken so that
the mediimi may not boil up to the cotton plugs. Anaerobic jars
which do not require exhaustion are preferable for re^incubation
of cultures.
The commonest contaminators of my cultures have been cocci
and molds, not anaerobes. The reason that anaerobic contami-
nation of anaerobe cultures is so very common probably lies
principally in the uncritical handling of such cultures. If a coc-
cus or mold contaminates a culture the worker inunediately kills
such an organism, but if an anaerobe enters the tube it proceeds to
multiply unmolested. Daily watchful observation of the cul-
tures studied is absolutely necessary for successful anaerobic work.
I have not f oimd indications of any so-called symbiotic tendency
that makes anaerobes more difficult to isolate than aerobes.
Anaerobes vary greatly in their behavior and requirements, and
the method of isolation must be adapted to the problem in hand as
ittiu*nsup. Each combination of two or more species of organ-
isms presents different elements for consideration and for adap-
tation of technique. There is no one method that is always best,
and it is only after a worker knows something about the nature of
the particular organisms that he is dealing with, their cultural
behavior, and their morphology in the medium in which he reg-
ularly grows them, that he is able quickly and surely to isolate
numbers of strains.
ISOLATION OF ANAEROBES
447
It is, of course, desirable to make use of methods that may be
applied to the largest possible number of species, that are easy of
manipulation, and moderate as to cost of time and material.
The organisms present in material to be investigated may belong
in any one of four large groups, which may be described as follows:
OBOANU1I9
VNOISIBABLB
DBIIBABLB
Easily killed by heat
Non-fliponilating aerobes,
Non-sporulating anaerobes:
common, many species
Welch bacillus is, in most
media, the chief consider-
ation
Not easily killed by
Sporulating aerobes, not
Sporulating anaerobes, spe-
heat
common in pathological
material; species numer-
ous, however
cies legion in number
Whatever be the material that is to be investigated, a micro-
scopic examination of a Gram stain is first in order. Practice
only will enable the worker to form judgments which will be of
value to him. As hints to the beginner, one may suggest that
there are an endless niunber of species of anaerobes and that
specific diagnosis by microscopic examination is futile. There
are frequently many species of anaerobes in the material that
finds its way to a laboratory, and, unless a study of many strains
is intended, the isolation or demonstration of a single species,
whose nature is guessed at, must be attempted. If the micro-
scope shows the probability of the presence of that species, matters
are simplified. To seek a certain organism one should familiar-
ize himself with a pure strain of that type of organism, or study
photographs or drawings of it; verbal descriptions are not of
much value. He should also learn the colony form of several
strains of the type he desires to obtain. The employment of a
mediimi in which the morphology of the organisms is varied and
characteristic is imperative. This laboratory uses chopped meat
medium containing 5 per cent peptic digest broth (pH 7.2) for
routine cultivation and this medium excels all other autoclaved
media in the above respect. The use of oil over the medium to
JOUBXAL or BACTBBIOLOOT, TOL. TI, HO. 6
448 HILDA HEMPL HELLEB
produce anaerobiosis should be avoided whenever possible for
routine work, as it interferes with the making of satisfactory
smears; for long incubation and imder certain circumstances de-
manded by technical considerations, vaseline will be found very
useful. Ghon and Sachs recommend the use of agar for strati-
fication; liquid media should be frozen before the agar is poured.
Heating. To free sporulating organisms from non-sponilating
organisms heating is always resorted to. Heating of inoculimi
may be performed in one of two ways. Heavily inoculated media
may be heated to 80** in a water bath for fifteen to thirty minutes.
This method is highly inaccurate, especially in case pasty media
are used, but it serves on occasion. Or the material to be in-
oculated may be heated in a Pasteur pipette after the following
fashion:
Sera, exudates, and muscle extracts should be diluted with
sterile saline. Cut the end of a Pasteur pipette off square with a
file, flame it, then draw up the inoculum for about two inches by
capillary attraction, and seal the pipette with less than a quarter
of an inch of air space between the tip and the liquid. To kill
non-spor ulating organisms heat in a waterbath for ten minutes
at 70^ to 72^. Then flame the pipette above the inoculum to kill
organisms that may have been above the water-line, mark the
tip in several places with the file or diamond, slowly flame the tip,
insert it in the tube of fresh medium, flame a pair of light forceps
and with them break the tip of the pipette against the inner wall
of the tube and expel the material.
If a worker is certain that the type of sporulating anaerobe de-
sired is always highly resistant to heat, he may use higher tem-
peratiu'es, in the neighborhood of lOO^C. for heating his cultures.
Dr. K. F. Meyer informs me that he has repeatedly employed
this method with success in the isolation of Bacillus botulinus.
Von Hibler sowed mixtures containing such organisms, and even
less resistant ones, directly into hot agar. Some strains of B.
hotulinuB and of Novy 's bacillus are highly resistant to heat.
ISOLATION OF ANAEBOBES 449
L To segarate n(m^porvlaling anaerobes from aerobes '
1. Heat to 56^-58^ for five or ten minutes. This occasionally
serves the purpose.
2. Try to induce sporulation by growing the mixture on al-
kaline sugar-free mediiun^ such as alkaline egg, or serum medium
(von Hibler, 1908, p. 189). When the anaerobes form spores,
heat. This procedure is a sure method of freeing B. Welchii from
ordinary aerobes : incubate for four days. This organism is found
in a sporulating condition in soil and in fecal material.
3. Try a pathogenicity test. If the organism sought is patho-
genic it may be recovered in pure culture from the animal tissues.
Use this method for B. Welchii, B. egens^ B. fdllax.
4. Use selective media. For the Welch bacillus use milk or 1
per cent glucose broth. Inoculate it with a pipette, a fresh tube
of medium every twelve hours if possible.
5. Use good anaerobic methods. Cultivate the material on
meat medium in strict anaerobiosis, inoculate in agar dilution
tubes that have been thoroughly boiled, and fish the colonies.
This technique is described on page 461.
6. Nqrthrup suggests the use of a 25-cc. burette, in which the
organisms of an inoculated mixture will, on short incubation, sort
themselves out, the aerobes growing above, the anaerobes below,
where they may be drawn off through a stopcock.
II. To separate non-^oruUUing anaerobes or reluctantly sporu^
lating anaerobes from other sporulating anaerobes
1. Use selective media, milk, with short incubation periods,
for B. Welchii.
2. Use animal inoculation.
3. Use shake cultures.
4. Use semi-anaerobiosis: The non-sporulating anaerobes are
naturally more resistant to oxygen than the sporulating ones.
Aside from B. Welchii this sort of organism is rarely sought after
or noticed. Few non-sporulating anaerobes are described, and
the group has been generally neglected, but careful methods show
that non-sporulating anaerobic rods and cocci are not unconmion.
450 HILDA HEMPL HELLER
///. To separate either variety of anaerobes from sporaUding
aerobes
Sporulating aerobes are rather infrequently found in patho-
logical material. One meets them frequently, however, in a me-
dium that has been insufficiently sterilized. My encounters with
sporulating aerobes have been so rare that it would be wise to
recommend that a worker always go back to the original material
and test it for the presence of any sporulating aerobe that he finds
in a culture with which he is working. Avoid sporulating aerobes,
do not contaminate cultures with them, and isolate the anaerobes
from the original material again.
1. Sporulating aerobes are of two classes: strict aerobes (any
good anaerobic technique followed by a colony method will free a
culture of these) and facultative anaerobes. I have never en-
coimtered a sporulating facultatively-anaerobic aerobe that grew
better under strictly anaerobic conditions than its accompanying
anaerobes. Any strictly anaerobic colony methpd that will sep-
arate anaerobes from each other will separate them from aerobes.
In my experience trouble with abundantly growing aerobic organ-
isms denotes faulty anaerobiosis : the presence of a small amount
of oxygen that permits the undue multiplication of the aerobes.
My experience has, however, been almost entirely with patho-
logical material and I may have failed to meet with the most
troublesome aerobic organisms.
2. Kitasato and Weyl found that anaerobes were less sen-
sitive to pjrrocatechin, chinon, sodiimi formate, and sodium sul-
phindigotate than were the aerobes causative of cholera, typhoid
and anthrax. Rivas continued this type of investigation.
3. Churchman has investigated the inhibitive effect of gentian
violet on aerobic growth. Hall recommends the use of gentian
violet in a dilution of 1 :100,000 to separate sporulating aerobes
from anaerobes. This, I should think, would work very well for
the heavy Gram positive organisms of the B. sybtiUs group, pro-
vided the desired anaerobe is not of the same nature.
4. The spores of aerobes may sometimes be satisfactorily ger-
minated in broth in a Petri dish, the broth being then heated and
inoculated into agar.
ISOLATION OF ANAEROBES
451
IV. To separate sporulaling anaerobes from non-^oriLlaHng
anaerobes and aerobes
Heat as described on page 448.
V. To separate sporulating anaerobes from other spondating
anaerobes by cultural methods
I. Heeding. The foUowing diagram shows how heating may be
employed:
▲KABXOBXC BACTBBIA
Early spondating species
(IS-H hours)
Later sporulating species
(ijh4S hours)
Late sporulating species (4S
hours on)
PBOTXOLmO OSOUP
Bif ermentans group et aliu
Do not occur very fre-
quently
Sporogenes group et alii
Tetanus group, botulinus
group, et alii
NOW-FBOTXOLTTIO QBOUP
Nearly all sporulat*
ing organisms
This diagram shows that if proteolytic early-sporulating organ-
isms are absent, as is frequently the case, a saccharolytic form may
be isolated or be rendered relatively far more abimdant by heating
eighteen to twenty-f om'-hour cultures successively. I have had
mixtures of B. sporogenes and organisms of the blackleg, group
that were not pathogenic for guineap-pigs because of the scarcity
of B. Chauvoei. Two successive heatings and inoculations made
blackleg the predominant organism and the culture was highly
pathogenic. This method is also excellent for organisms of the
vibrion-septique group and for many non-pathogenic sacchar-
olytic bacteria, as well as the early-sporulating proteolytic ones.
II. Selective media. Isolation methods usually depend on se-
curing a predominance of the organism sought. To increase the
relative numbers of an organism with whose nature one is familiar,
a medium should be selected on which the organism grows best.
For saccharolytic species mixed with proteolytic ones, use sugar-
containing media. Meat medium plus 1 per cent glucose is
452 HILDA HSMPL HELLER
good| meat medium not neutralized in the making is also good
Ordinary meat medium, the culture being taken early in its de-
velopmenty is usually sufficiently selective. Sugar media selective
for certain groups may be used, if the number of cultures to be iso-
lated warrants the investigation of the sugars split by that group.
I have found thatcultureincasein-digestliver-brothrendersblack-
leg the most able guinea-pig invader in ablackleg-vibrion-septique
mixture. To increase the percentage of proteolytic organisms use
meat medium or brain medium in a culture two to four days old|Or
even older; or employ the medium of Achalme-Passini, salt solution
or broth containing cubes of egg-white; or use serum medium or
other sugar-free media; or a medium made up at pH 8.0 or above.
For an organism whose morphology interests one and whose nature
is not known, experiments should be tried with various media,
and the behavior of the mixture should be studied. Under labora-
tory conditions certain types always tend to disappear from mixed
cultures. It must be kept in mind that conditions must exist in
nature which favor the multiplication of such species or they
would have died out long ago. For such organisms try media of
vegetable origin.
In taking samples of pathological material enrichment with the
tissue in which the organisms are found is advisable. Schott-
miiller isolated septicemic streptococci in blood-glucose agar
shakes. The many tissue-containing media favor the growth of
pathogens. (Media smnmarized by Pfuhl.) Tunniclifife used
sermn and ascites agar for the anaerobic coccus found by her in
measles cases. Plotz and his co-workers added ascites or hydro-
cele fluid to glucose agar for blood cultures from their typhus
patients. Dick and Henry employed blood-glucose agar for
the various anaerobes found in the blood of scarlet fever
patients. Leucowicz used serum-sugar agar for Fu^formia.
Digest media are excellent for anaerobes. A number of such
media are discussed by Stickel and Meyer.
Serious problems sometimes arise. Thus, B. tetani is particu-
larly difficult to isolate from gross mixtures, as it is not a tissue
invader, and because it sporulates later than the organisms that
usually accompany it. In case an organism like B. tetani grows
ISOLATION OF ANAEBOBES 453
excellently on a given medium but its accompanying organisms
grow better than it does, try similar selective media of modified
reaction, or make use of exhaust media of the type recommended
by Tulloch. One may always grow the objectionable species or
several species in a medium till growth ceases, filter the medium
and then grow the mixed culture in the filtrate. In case this fails
one may add a minute quantity of some solid protein for a starter.
Tulloch added a bit of rabbit kidney to an exhaust filtrate and
found it highly selective for B. tetani. Von Hibler grew mixtures
containing B. tetani on clotted rabbits' blood and stated it to be
selective for that organism. But his photographs of the organism
show his cultures to have been so badly contaminated that he
may have been mistaken.
I have found a modification of a medium of Beijerinck's excel-
lent for the enrichment of soil anaerobes (sodium phosphate 0.05
per cent, ammonium sulphate 0.05 per cent, soluble starch 1 per
per cent, calcium carbonate 0.5 per cent). The anaerobic flora
obtained in such a medium after heating a soil emulsion is very
different from that obtained in meat or other media of complex
composition. By fishing large lenticular or modified lenticular
colonies from 2 per cent agar shakes of this medium which have
been incubated for four days, the large but3rric acid bacteria of
the genus Clostridium may be isolated with comparative ease.
Winogradsky (1902) recommends the use of media free of fixed
nitrogen for the isolation of nitrogen fixing anaerobes ( Clostri-
dium Pastorianum) ; this medium is described by Fred (1916)
and Bredemann used it for the isolation of his Badllua amyUh
bacter which he considers to be the same organism as Winograd-
sky's. Milk may also be used as an enrichment medium for many
organisms of this genus.
Omeliansky (1904) describes the following method for enrich-
ing cellulose fermenters: Place in a long-necked flask any cel-
lulose substance, paper, cotton, flax ; add chalk, and fill to the top
with water which contains 0.1 per cent ammonium phosphate, 0.1
per cent calcium phosphate, 0.05 per cent magnesium sulphate,
and a little sodium chloride. Inoculate with slime or horse ma^
nure, cover, and set in the dark. In other publications (1895;
454 HILDA HEMPL HELLER
1902) he gives other formulae ; several are given by Fred. Anker-
schmitt used physiological salt solution containing cubes of
potato to enrich splitters of hemicellulose. Choukevitch ein-
ployed 1 per cent pepton broth with 5 per cent starch for starch
splitting organisms. Silicate jelly as a substrate for such of these
organisms as will not grow on agar is described by Omeliansky
(1899) and formulae for similar jellies are given by Fred and by
Ktister.
III. SynibumU have been used to enrich certain types of anaer-
obes. Sturges and Rettger foimd that B. pvtrificus floiuished
best in the presence of Bact. coli, and used the latter as a symbiont
for the former. Rhein used Bact. faecaUs-alcaUgenes as a sym-
biont for anaerobes, cultivating them in the presence of air: this
organism has several advantages. Wilson and Store describe a
cocco-bacillus which is an excellent anaerobe symbiont.
IV. Another resource is to test the resistance of the desired spe-
cies to unfavorable circumstances. Thus McCoy and Bengtson of
United States Pubhc Health Laboratory isolated many strains of
tetanus with great ease by heating toxic strains at 70^ for a half
hour and inoculating the spores in veal agar dilution shakes.
This technique is adverse for an anaerobe, but B. tetani appeara
to be hardy enough to withstand it. Modified highly acid or
alkaline media, or media poor in protein may be used for such pur-
poses. A pure strain of the desired organism is invaluable in test-
ing out media of this sort.
V. Aniline dyes may be used to eliminate certain species of or-
ganisms and the possibilities which they offer are almost imlimited.
VI. Selective temperatures may be employed for enrichment of
various organisms. B. hotuUnvs was long thought to produce
toxin at low temperatures only, because the contaminating or-
ganisms in the cultures outgrew it at 37^. Thermophilic organ-
isms are of various types, and are discussed by Bergey. Major
W. J. Tulloch tells me that the flora obtained by incubating a
mixture of anaerobes in meat medium at 42® is quite different
from that obtained at 37®, slender, oval end-sporing organisn^
predominating. It is probable that anaerobic organisms will be
found that grow at much higher temperatures than at 42®.
ISOLATION OF ANAEROBES . 455
VII. Separation of arganiama hefore mowing was suggested by
Stoddard, who shook his material with sea sand to separate en-
capsulated or autoagglutinated organisms. Dr. K. F. Meyer
tells me that he has found such technique useful in isolating an-
aerobes from 'soil and from old meat cultures which had sporu-
lated heavily. Such separation is not necessary when fresh
cultures are used.
VIII. I solationhy variay^ colony methods. Because of the confu-
sion that exists as to the purity of cultures of anaerobes, it will
be well to study the biological factors involved in the genesis of
bacterial colonies. A colony is an aggregation of organisms that
are prevented from mixing with other organisms by a physical
obstruction. A colony may be defined as follows :
a. From one single organism — the ideal colony for isolation
purposes.
b. From two or more organisms descended directly or indirectly
from one organism — a satisfactory colony for isolation purposes.
c. From two or more organisms of closely related strains — the
most imdesirable type of colony for isolation purposes.
d. Or from two or more organisms of unrelated strains — an im-
desirable type of colony for isolation purposes. This type or a
contaminated pure colony is sometimes useful in procuring a new
proportional mixture of strains.
Broadly speaking a colony may consist of any number of
organisms from one to infinity. Technically speaking a colony
consists of the organisms confined within a certain radius
inside of or on the surface of the mass of colloid gel. For
purposes of discussion, let us define a bacterial colony
as the uncontaminated descendant of a very small number
of organisms, irrespective of the medium in which they are
found. It will be realized that this definition covers perfectly
the biological factors involved in the derivation of any ordinary
agar or gelatin colony.
Colony methods available for the isolation of anaerobes are the
following:
456 . HILDA HEBfPL HELLEB
I. Agar colonies — ^von Hibler and older workers used also gelatin.
A. Surface colonies.
1. On plates.
2. On tube slants.
B. Deep colonies.
1. In Petri dishes.
2. In deep agar tubes.
II. Colonies in liquid media.
A. Isolation of a single bacillus by the India-ink method.
B. Isolation of a sin^e bacillus or of a small number of organisms
by the technique of Barber.
C. Isolation of a single bacillus by the technique of Schouten,
of Hecker, of Holker, or that of Malone.
Isolation from surface colonies has been employed by many work-
ers with ana.erobes. Veillon and Zuber list a large number of
types of anaerobic apparatus, von Hibler (1908) gives a bibli-
ography of various plates and apparatus for purposes of anaerobic
culture, Besson 's textbook figures a niunber of arrangements, and
Fildes describes various methods at the end of Mcintosh 's report.
Henry uses plates of agar which he streaks with egg-albumen
and incubates in hydrogen. Stoddard uses slants made of the
modified egg medium of Stitt, made with tryptic broth and 1 per
cent glucose. Zeissler, who at first used glucose agar plates con-
taining himian blood for the isolation of anaerobes, later employed
horse blood and sheep blood agar plates. Many laboratories now
make use of large slants of blood agar, kept under anaerobic con-
ditions for the isolation of anaerobes. Isolation of nitrogen fix-
ing organisms was accomplished by Winogradsky by inoculating
cultures on pieces of carrot which he placed in vacuo, and Fribes
isolated pectin f ermenters on potato slants rubbed with chalk.
Mcintosh prefers agar slants to plates for isolation procedure.
He reiterates: ''It cannot here be impressed too strongly on the
worker that the purity of a culture can only be tested and con-
trolled by repeated surface cultivation,' ' and he speaks of the
Veillon-tube method of continental workers as giving impure
cultures. I have used plating occasionally and am familiar with
technique necessary to make anaerobes grow on plates. In fact
ISOLATION OF ANAEBOBES 457
it was the first method for the isolation of anaerobes that I learned
to use. It is a perfectly feasible method, but I find it to be less
satisfactory than others for various reasons.
The difficiilty of regulating the amoimt of moisture on the sur-
face of the plate or slant is the primary drawback to the use of
surface methods. Aerobic cultures differ fundamentally from
anaerobic ones in this respect. They are, so to speak, self-rc^gula-
ting in their moisture content. When a plate is poured, the sur-
face of the agar is exceedingly moist, and the organisms planted
in it grow rapidly till their growth is inhibited by the drying at-
mosphere of the incubator. Moisture conditions are fairly uni-
form in ordinary bacteriological technique; colonies of most
species are discrete and characteristic. The colonies, when
few, are usually pure; the viable aerobes usually all form colonies,
and the method as a whole is easy and practical. But with an-
aerobes the moisture content of the medium and the moisture on
its surface become of great importance. I have known agar in
deep tubes of medium, which had given perfect results with black-
leg colonies, to refuse to give a growth of blackleg when it was
somewhat old and dried out, though the agar had nowhere, as yet,
separated from the side of the tube. The addition of sterile dis-
tilled water made the medium as fertile a soil as fresh agar. I
have encoimtered aerobes which grow to the surface of the agar of
a shake, but not in colonies upon its surface. How much more
would drjmess affect the growth of the more delicate anaerobic
organisms on the surface of a plate! Even the hardy tetanus or-
ganisms, which grow well in dry deep agar, often refuse to grow on
its surface. In order to produce discrete anaerobic colonies plates
must be dried after pouring. They must be dried just long enough
and not too long. This period varies with the composition, age
and thickness of the agar, with the humidity of the atmosphere,
and with the moisture present in the anaerobic jar. It takes time
and patience to learn to adjust the period for drying the plates.
Then when the culture is sown and the plates are ready to incu-
bate, what have we for anaerobic methods? A variety of available
atmospheres for the growth of the organisms almost as great as is
the number of workers in the anaerobic field : Hydrogen, carbon-
458 HILDA HEMPL HELLER
dioxidei nitrogen, illuminating gas, nitrogen-hydrogenH»rbon-di-
oxide and vacuum with varying degrees of moisture, pressure and
oxygen present. How can one hope to standardize type colonies
under such conditions? And what,may we ask, tstheproper mois-
ture for the surface of a plate? There is no universal proper mois-
ture. Agar moist enough to grow tetanus will allow the spread of B.
sparogenestiJl the B.aparogenea has increased a million times more
than the tetanus has. Some mixtures of organisms allow isolation
of their components by surface methods, and some do not. When
discouraged with plates that haye dried too long, the worker
dries them less, and finds to his joy beautifxil discrete colonies,
some round and some lobed. He must fish them immediately
onto plates or into a deep medium or they may die. But let him
beware of a pitfall. Let him hold them to the light without
a cover and look betw;een the colonies. A slight film of moisture
there may represent a spread of growth which contaminates all
his colonies. But such a spread may be diJBBcult or impossible
of detection. A fragment of coverslip dropped between colonies
may show bacilli. I venture to suggest that it is almost impos-
sible to determine in an agar slant the non-existence of such a thin
spread, and such a thin spreading film is far more likely to occur
in the confines of a tube than on a plate.
Methods of spreading a culture on a surface do not separate the
individual organisms from one another so well as does a shaking
in liquid agar — ^in properly made shakes the colonies are beauti-
fully distributed.
Other minor disadvantages of a surface method are that the
plates must be incubated unmediately after sowing and be fished
immediately after opening ; they are usually valueless when reincu-
bated after opening for inspection because of too much drying, and
they require the use of more glassware than do deep-tube methods,
and also the use of an anaerobic jar or other anaerobic apparatus.
The method of Marino should be recommended for organisnis
which form minute colonies, and for demonstration plates.
Marino poured inoculated agar in the upper half of a Petri dish,
and covered it directly with the inverted lower half, and covered
the whole with a larger Petri dish. This method is convenient but
ISOLATION OF ANASBOBBB 459
not niecessary for photographic work, as sections for that purpose
may be cut from tubes of agar and may then be moimted between
cover and slide. Fehrs and Sachs-Mflcke used a similar method,
covering the agar with a photographic plate. Krumwiede and
Pratt used Marino's method satisfactorily for the isolation of fusi-
form bacilli, sealing the open crack with wax. Rhein used it with
satisfaction for general anaerobic work, pouring a sterile agar layer
on either side of the inocvdated one. Dick used the method of
Rhein, replacing the top dish by a layer of paraffin. All these
methods are probably preferable to surface plating for isolation
purposes, but are somewhat cumbersome.
Foth complains that the invention of new anaerobic methods
has become a sort of sport. Many procedures are too complicated
to use, though most methods will serve well for the cultivation of
anaerobes. It would seem as though any method employing
sticky black pyrogallic acid and alkali should be avoided, or at
least only chosen in the modification of Lentz.
Certain workers with surface methods have charged that deep
colon}' procedures do not give pure cultures. Either type of pro-
cedure will give pure ctiltures in the hands of the critical worker
and impure ones in the hands of the uncritical one. But I have
found in making a large collection of anaerobes that the cultures
from laboratories whose isolation procedure was a deep colony
method were more often pure than those f roim laboratories where
surface methods were preferred, and I believe that, with the same
amoimt of labor, the same expenditure of time and material, and
the same degree of critique, the deep-colony methods are more
successful than are surface ones.
Deep-colony methods have been described by the Hesses,
by liborius, and by Veillon and Zuber, and they have been
used extensively by von Hibler, Burri, and by French workers.
Von Hibler (1908) preferred deep colony isolation to plate methods
because of the fact that water of condensation was likely to render
plates worthless.
The selection of a suitable medium for deep-colony isolation is
an essential to its success. For general work the primary require-
ment is that the nutriment in the medium allow every anaerobe
460 HILDA HEMPL HELLEB
present to grow and form a colony. Otherwise colonies may be
fished through agar that contains living invisible organisms of
other species, and the most deceptive sort of contamination will
take place. The mediiun should be clear and transparent. Our
standard agar medium for routine work is made of beef liver.
The usual proportion of one part of meat to two of water gave too
active a growth and too much gas. The medium is made as
follows:
One part of ground beef liver and four parts of distilled water
are infused over night, boiled, and strained. To the broth add
1.5 per cent peptone, 0.5 per cent salt, and for ordinary purposes
make up with 2 per cent agar pH 7.2 (faintly alkaline to litmus).
When unusually active gas-producers are present, high dilu-
tions and short (twelve hours) incubation periods are resorted to.
Such methods always sufSce when rapidly growing species are
the ones to be isolated. But when slowly growing species are
sought in the presence of actively growing ones, other methods
are available. To absorb hydrogen, 1 per cent potassium nitrate
may be added to the agar (Veillon and Maz6). To prevent the
colonies of the rapidly growing types from outnmning the others,
use 3 per cent agar or old agar that has partially dried out, or pay
particular attention to enrichment of the desired species in the
inoculum and employ abundant dilution tubes. Do not depend
upon any colony method for the isolation of badly contaminated
slowly growing tissue invaders, but resort directly to guinea-pig
inoculation. For slowly growing non-pathogenic organisms mixed
with rankly growing gas-producers, try a sugar-free agar (von
Hibler,1908).
There is an essential point in the emplojrment of deep colony
tubes which must be observed. Otherwise the method is of no
more use than any other. Actively growing anaerobes fre-
quently leave their colonies and grow in the agar as though it were
a broth.
This happens more readily with some types of organisms
than with othera. B. Welchii is the chief offender and should be
avoided by heating whenever possible. A tube in which this phe-
nomenon has occurred is readily identified by holding it to the
ISOLATION OF ANAEBOBES 461
light with a control. Such tubes are to be regarded as '^ enrich-
ment cultures. " Thus their colonies may be of great use when
directly inoculated onto another agar series. They are of no use
when inoculated into a liquid medium. The close observation of
this phenomenon of ' ' permeating growth ' ' cannot be too earnestly
insisted upon.
The deep colonies of anaerobes are highly characteristic.
Surface colonies are quite characteristic but are obviously sub-
ject to many more outside influences than are deep ones. Often
colonies of different strains in the same species are different and
sometimes colonies of one type of anaerobe resemble those of an
entirely different type. But carefully made agar shakes often
give a beautiful picture of the flora of a woimd or of a culture.
They are very easily observed with a hand lens and may be as
closely approached as may siuface colonies. Aerobic growth is
easily distinguished from anaerobic growth. My routine method
of testing for impurity of culture has been to make three dilution
shakes on liver agar. The first and second tubes tell whether or
not the ctilture is pure. The third usually furnishes colonies
suitable for fishing. I was able to isolate, in two series of three
agar tubes each, a strain of oedemaiiens type that had been over-
grown 1 : 500 by a vibrion septique.
Technique of sowing and fishing. Boil the tubes of agar for a
minute or two, remove them from the water, shake them, boil
them a little longer, shake them again to remove the air, then cool
them to 45^. Do not boil them for ten or fifteen minutes or the
cotton will become saturated with moisture. For ordinary pur-
poses use three tubes to each culture. For new and important
material of doubtful nature or for shyly growing organisms among
rankly growing ones, use more tubes. Inoculate tube 1 with
oneloopful of culture and roll it, tip it, and roll it four or five times.
Take a Fasteur pipette^ of large bore, flame it, draw up agar of tube
^ It is to be noted that few laboratory workers today understand the mRlri^g
of strong and serviceable Pasteur pipettes, and I hope to be pardoned for de-
scribing so simple an operation. Meeker burners are best for this purpose. Heat
the glass in the portion of the flame where the heat is nearly uniform for a con-
siderable distance. In a blowpipe or Bunsen flame this is above the cone; in
the flame of the Meeker burner it is half an inch above the base. Turn the glass
462 HILDA HSMPL HSLLEB
1, expel it, draw up fresh agar and expel it into tube 2. For cul-
tures containing abundant organisms, give tube 2 2 inches of agar
measured in the capillary portion of the tube. For ordinary cultures
give 5 inches, for B. Novyi, etc., give about two capillaries full.
Place the inoculum throughout the.length of the agar while with-
drawing the pipette, but do not blow air into the agar of tube 2.
Roll tube 2. Flame the Pasteur pipette. By means of it place
agar from tube 2 in tube 3 to the amount of 0.5 to 1 inch on the
upper or thick portion of the Pasteur pipette. Roll the tube.
Incubate aerobically at 37^. If actively growing species are
present, incubate twelve hours. Otherwise incubate eighteen to
twenty-four hours. For blackleg, Clostridia, and unknown shy
types, incubate four days. Examine the colonies with a hand lens.
Look for permeating growth. It is better, in fishing from a tube
containing more than one type of colony, to fish once more onto
a series of agar tubes. Final isolation should be made from colo-
nies of mixed cultures. Study the tubes carefully with a hand lens,
noting minute colonies and aerobic growth. Select the tube to be
fished, and, if possible, select the colonies desired. Take a well-
made, strong Pasteiu* pipette of fairly large bore, bend it at right
angles where the capillary begins, break the tip, flame the whole
capillary. Remove the plug from the tube and loose fibers of cot-
ton from its opening, insert the Pasteur pipette along the side to
the bottom, remove and empty it of agar ; re-insert' it, and blow the
whole colunm of agar into a sterile Petri dish. The large Pasteur
pipette may be used many times. One-half Petri dish serves for
each tube. Take a short-stemmed Pasteur pipette, hold it in the
flame, draw the capillary out to a hair-like tube, and break it off
fairly short. Suck up. the desired colony and expel it into a tube
of meat medium or tube 1 of another agar series. Draw out the
coDBtantly but slowly in the same direction, not forwards and backwards. Con-
tinue tm the hot portion softens and contracts to about four-fifths of its fonner
diameter. Never puU the glass while it is in the flame. Remove the rod from
the flame and wait a second, then pull slowly. If the glass is puUed too soon or
too quickly the fine bore is formed from the hottest portion only, and not fron
aU the heated glass, the bore is smaU, and its walls are thin and weak. An hoor'i
continuous practice is necessary to begin with; the art, once learned, is extremely
useful and is not forgotten.
ISOLATION OF ANAEROBES 463
pipette again, flaming it well, and use it to isolate two or three more
colonies. Other workers employ other methods, which are prob-
ably as good. Burri (1902) recommends the use of tubes open at
both ends with an autoclaved rubber stopper placed in the lower
end. Some use the loop only for purposes of dilution. Some heat
the end of the test tube and expel the agar column by force of the
steam thus generated. It is necessary to break the tube at the
bottom only when an aerobe is present. Butke used a dissecting
lens with stand for fishing colonies; Dr. Meyer finds a bmoctilar a
great help in some cases. He sections the agar with a sterile blade
when researching for minute colonies that are rare. Some workers
prefer to attach a rubber tube or a teat to the pipette used in fish-
ing. It is theoretically wrong to fish the colonies from* the top of
the column of agar without removing it from the tube, because the
capillary may pass ungerminated organisms, but such a method
might prove practical when used with discretion. Some workers
fish the colonies with a platinum needle, but this would hardly
prove as satisfactory as a pipette method.
Methods of singte-badUiLS isolation. Isolation of a single bacil-
lus has been resorted to for the separation of anaerobes. Miss
Robertson found that the India-ink method of Burri (Besson 1913)
exposed the organisms too much and they failed to germinate. I
used the Barber method for some time for blackleg and vibrion-
septique organisms,, and found that the exposure killed vegetative
forms and that spores were necessary to give a growth. I fished
from apparently pure cultures various numbers of organisms, from
one to ten, into meat tubes and used for a type strain the tube
that grew and had received the fewest bacilli. I found the method
wasteful of time, material, eyesight, and nervous energy, and have
abandoned it. My employment of the apparatus was, however,
far from being as skillful as that of Dr. Barber. I explained my
diflSculties to Dr. Barber and he (1920) has made a careful statis-
tical study of the behavior of various anaerobes when isolated by
his technique. He was successful when inociilating various media
with different anaerobes in securing 62 growths from 400 single
bacilli, and 93 growths from 211 single spores. Vegetative rods
464 HILDA HEMPL HELLEB
of vibrion-fleptique were particularly sensitive to the air. Bar-
ber found the semi-solid medium of Ligni^res excellent for
securing growth of single anaerobes. Colonies could be secured
from spores in a chamber containing a Paeudomanas pyocyanea
culture.
Malone and Holker have devised pipette methods for single
bacillus isolation with which I have no personal experience. It
may be that they protect the organisms from air better than does
the Barber method. Hecker makes interesting technical
suggestions. Hort objects to all methods of single bacillus iso-
lation from liquids and he objects to capillary methods on account
of optical difficulties. The method preferred by Hort, the perfor-
ated plate method, is too aerobic for our purposes.
IX. Animal inoculation is frequently resorted to for the isolation
of anaerobes. The guinea-pig is the best animal for this purpose.
It is highly susceptible to infections and also develops very char-
acteristic lesions, of diagnostic value. Animal inoculation is of
prime value for recovering pathogens that have been badly over-
grown. It is the only way I know of to recover blackleg oi^an-
isms that have been grossly contaminated. A drop of lactic acid
may be used for a second trial, if the first fails. Inoculation of
mixtures from the involved tissues of gas-gangrene cases is of
course necessary, but it is likely to give misleading ideas as to the
flora of those tissues. It is advisable to run deep-colony cultures
from various portions of an amputated limb or of material derived
from tissue-pimcture or from a blood culture, and to inspect the
flora of the limb carefully. A culture or smear from the wound
itself may give very misleading data as to the etiology of a gan-
grenous process. I believe that the r61e played by B. Wdchii m
ga&-gangrene nf ections has been grossly exaggerated because of
the failure of many workers to study carefully the flora from
various portions of infected muscle. When the colony method has
^ven pure or apparently pure cultures, inoculate them into guinea-
pigs and record results. When immediate identification of patho-
gens is urgent, examine smears made by pimcture from affected
tissue remote from the wound. Conj ecture the possible types there
ISOLATION OF ANAEBOBES 465
represented; inoculate a series of guinearpigs with antitoxic or
antibacterial sera of the groups probably represented on the
smears, in such a manner that for each type of organism there is
a guinea-pig immunized against the other types only. Then in-
oculate the mixed material into all the guinea-pigs. This method
was found successful by the Committee. In large war hospitals
collections of guinea-pigs immunized by bacterial inoculation
have been kept for diagnostic purposes.
It is best to inbculate guinea-pigs in the thigh muscles. Take
cultures from various points in the body. The heart-blood cul-
ture is usually the most valuable. Oedematiens-group organisms
and some other pathogens do not always become septicemic,
however. Bifermentans-group organisms and other proteolytic
types may become septicemic. Inoculate into another guinea-
pig a culture from the heart-blood in smaller quantity than was
used before. If this fails, isolate the proteolytic organism,
immunize a guinea-pig with it, then inoculate the mixture. For
all animal work keep a careful record of the cultures inoculated,
incubation periods, lesions in the animals, and, above all, make
constant use of the microscope.
Anaerobic organisms should be sought in the following patho-
logical conditions:
Infected wounds (rods or cocci).
Gangrene.
Oedema.
Emphysema of muscles, connective-tissue, liver or other organs.
Haemorrhagic condition of muscles.
Pnexmionic processes where anaerobic infection is suspected, puhnonary
gangrene.
Necrosis of muscle or connective tissue (J5. necropfiarus et alii).
Injection of serous surfaces, especially in ruminants.
Abortion in animals (search foetus for Bad, abortum).
Endometritis, post abortum or post partum {Streptococcus).
Appendicitis and various ulcerative and suppurative conditions.
Tetanus (in absence of wounds and uterine infection, search for peri-
dental infection).
Botulism, intestinal content and wall, liver, spleen, stools from patients*
466 HILDA HEMPL HELLEB
Obscure fevers, measles, scarlet fever. Blood cultures, look for various
invaders.
Rhinitis, Vincent's angina; mucous surfaces.
Make smears of affected tissue, make meat or brain cultures and
make at the same time numerous shakes in deep liver-agar. Ex-
amine shakes twelve hours after incubation if possible, and
examine meat cultures twenty to twenty-four hours after incu-
bation. Blood cultures in broth, meat or agar should always be
made, if possible, ante mortem and post m^rrtem.
I wish to express my thanks to Dr. Karl F. Meyer for his active
interest and cooperation in this work.
SX7MMABT
As an aid to the isolation of anaerobes the following notes may
be observed :
1. Success in the isolation of anaerobes depends more on the
critical sense of the worker than on the method he employs.
2. Microscopic observation should be made of incoming- ma-
terial and of cultures after twenty-four and forty-eight hours'
incubation, and the development of a critical eye for the mor-
phology and staining reactions of anaerobes is imperative.
3. Heating of material should be executed according to the logi-
cal requirements for that material. Heating at 70^ in pipettes is
to be reconunended for routine work.
4. A routine medium should be employed which will favor as
many diverse forms as possible. Chopped beef heart, preferably
containing a little peptic digest broth, the reaction at about pH 7.2,
presents nunierous advantages as a routine medium, for most
of the anaerobes studied in a pathological laboratory. If
freshly boiled it is usually quite unnecessaiy to incubate it
anaerobically.
5. Selective media may be employed for special purposes, and
they offer many possibilities.
6. Isolation by means of guinea-pig inoculation, securing the
organism from the heart's blood or from the affected tissues re-
mote from the site of inoculation, is preferable for invading patho-
ISOLATION OF ANAEBOBBS 467
gens, but may not be depended upon to give a true picture of the
pathogenic flora of the material injected.
7. The making of dilution shakes in deep agar (method of Li-
borius and of Veillon) is to be preferred to other colony methods;
care must be taken to isolate for a type a colony from an appar-
ently pure culture.
8. A mediimi for dilution shakes should afford an opportunity
for growth to just a^ many species as possible. Such a medium is
pepton-liver agar, as described in the text.
9. When once pure, a culture should be carefully kept pure.
Re-incubation, prolonged incubation in closed jars, storing in
closed cans or in dusty places, are to be avoided. Autoclaved
media only should be employed for the preservation of type
ciiltures; one cannot be too careful as to routine technique.
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ISOLATION OF ANAEBOBES 469
Mabino, F. 1907 Methode pour isoler les ana^robies. Ann. de I'lnst. Past.,
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470 HILDA HEMPL HELLEB
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INDOL PRODUCTION BY BACTERIA
JOHN F. NORTON and MARY V. SAWYER
From the Department of Hygiene and Bacteriology, The UnioersUy of Chicago
Received for publication January 11, 1021
The formation of indol in certain culture media has long been
considered an important differential characteristic for the iden-
ification of bacteria. Special interest in the test has been recently
aroused in connection with investigations on respiratory diseases
because Pfeiffer's bacillus appears to be practically the only
mouth organism producing indol (Jordan, 1919, Malone, 1920) ; in
consequence of which Malone has suggested that the test be used
as an index of the presence of this organism without actually iso-
lating it. Rivers (1920) has made a similar suggestion for
diagnosis of influenzal meningitis. For this paper we have
attempted to collect from the literature the more recent informa-
tion, both positive and negative, concerning indol production by
bacteria. On accoimt of the uncertainty of indol tests much of
the older work is unreliable. This information has been supple-
mented by tests on over 180 strains of bacteria, most of which are
being carried as stock cultures in this laboratory and have been
collected from a great variety of sources. Incidentally we
have made a comprehensive comparison of three recommended
media and also determined the effect of the incubation period
on indol production.
MEDIA
Indol is a disintegration product of proteins containing the
tryptophane group. The ideal medium would therefore be one
to which pure trjrtophane had been added but on accoimt of the
difiSculty of obtaining the material it is impractical, although
Zipfel (1913) used such a medium. Dunham's pepton is the
easiest medium to prepare and has been most frequently used.
471
472 JOHN F. NORTON AND B£ART V. SAWYER
Sicre (1909) and Porcher (1911) have studied the use of various
peptons finding that some ah*eady contain indol and that with
others indol* is never produced by bacteria, so that it is necessary
not only to make blank tests on any chosen medimn but also to
control experiments with a known indol-producing organism.
In each instance our tests were controlled by inoculating one tube
of mediiun with BacL coli, an indol-forming organism, and
another with BacL typhosum^ a non-idol-former, and we regarded
such controls as essential. For media, besides Dunham's
pepton and the tryptophane medium of Zipf el, Rivas has suggested
trypsinized pepton (Rivas, 1912) and Cannon (1916), instead of
preparing pure trjrptophane from casein as was done by Zipfel,
used hydrolyzed casein as the basis for his medium.
Homer (1916) believes that tryptophane is necessary for bac-
terial life and if not present will be synthesized by the organisms.
Logic (1920) has used synthetic media containing ammonium
lactate with asparagin or sodiiun asparaginate and claims that
indol producing organisms possess an enzyme which enables them
to split off and utilize part of the tryptophane molecule. It is
possible that many organisms may be capable of synthesizing
indol but make use of it in their metabolism.
For the hemophilic group a heated blood broth has been used
(Jordan, 1919).
It is well known that the addition of glucose to a medium inter-
feres with the indol test. Fischer (1915) reports that lactose,
galactose, maltose or fructose are without effect. He believes
that this action of glucose is due not to acid production, as had
been supposed, but to the inactivation of the proteolytic enzyme
concerned in splitting the tryptophane. Logic (1920) found that
if glucose was added to a living culture of BacL coli in which
indol had already been produced the latter rapidly disappeared.
From this he concluded that glucose caused an increased demand
in the organism for indol. Homer (1916) explains the effect
of the presence of glucose either on the basis of the preference of
the organism for glucose over trjrptophane or by assuming the
formation of a chemical compound between glucose and trypto-
phane which is relatively stable.
INDOL PRODUCTION BY BACTERIA 473
We have used three media. (1) Dunham's pepton solution.
One per cent of pepton (Armour's) and 0.5 per cent sodium chloride
were dissolved in distilled water and the reaction adjusted to +1
to phenolphthalein. (2) Rivas' trypsinized pepton (Rivas
1912). Ten grams of pepton (Armour's) were dissolved in 200
cc. distilled water. To this was added a solution of 0.5 gram
trypsin in 10 cc. of water (trypsin dissolved by shaking and gentle
heating not over 40®C.) and digestion allowed to continue for three
hours at 37°C., with frequent stirring. The solution was then
made up to 1 liter and reaction adjusted to + 1 to phenolphtha-
lein. (3) Cannon's casein medium (Cannon, 1916). Twenty
grams of chemically pure casein were added to 250 cc. distilled
water and the whole made alkaline to phenolphthalein with
sodium carbonate. One-half gram of trypsin w*as added and the
casein allowed to digest for six hours. The medium was then
autoclaved and 5 grams each of asparagin and ammonium lactate,
2 grains of dipotassium phosphate and 0.2 gram magnesium
sulphate were added. The solution was made up to 1 liter and
reaction adjusted to + 1 to phenolphthalein.
A large number of comparative tests were made on these three
media. In no case did the final indol test vary but a positive
reaction was obtained more quickly, and the color tests were
stronger, with the trypsinized casein or pepton than with
Dunham's pepton solution. Positive tests with the trypsinized
pepton were noted after six hours incubation with BaqL coli and
color production with Ehrlich's reagent was at its maximum at the
end of twenty-four hours. With Dunham's solution the max-
imum was obtained only after four days. After six days the
indol began to disappear. As most of our tests were made
simultaneously on all three media we used the four day period,
although forty-eight hours is suflScient for the trsrpsinized media.
The influence of oxygen supply on indol formation has been
studied by Porcher and Panisset (1911). They found that
growing cultures of the colon bacillus and of proteus anaerobi-
cally decreased the amount of indol formed, while if a current of
oxygen was kept going through the flask, the amount was in-
creased. However, they were unable to provoke the formation
474 JOHN p. NORTON AND MART V. SAWTBR
of indol by BacL typhosum by an oxygen current. Our cultures
were incubated aerobically, except in the case of the strict
anaerobes.
INDOL REAGENTS
Numerous tests for indol have been suggested and used.
Nelson (1916) gives four: (1) dimethylamine, glycolic acid,
glyceric aldehyde and sulphuric acid, giving a pink color; (2) per-
uvic aldehydei sulphuric acid and ferric sulphate, giving a violet
color; (3) vanillin and an acid, giving an orange color; (4)
Salkowski test — sulphuric acid and potassium nitrite, giving a
pink to red ring. Escallon (1908) recommends furfural. This,
in the presence of hydrochloric acid, gives an orange yellow
color. It is claimed that this test is sensitive to 1 part in 800,000.
Baudisch (1915) describes a reaction using nitromethane. By
far the most satisfactory test is that suggested by Ehrlich (1901).
The reagent is prepared by dissolving 4 grams of paradimethyl-
amido-benzaldehyde in 380 cc. of alcohol and adding 80 cc. of
concentrated hydrochloric acid, A red color is formed in the
presence of indol at the junction of the reagent and the liquid to
be tested if the former is added so that it forms a layer on top.
A solution of potassium persulphate is sometimes added to bring
out the color more clearly but we have found the reagent quite
satisfactory without this. In making our tests, if a red color
appeared on adding the Ehrlich reagent, 1 cc. of amyl alcohol
was added and the tube shaken. The red coloring matter, if
due to indol, is soluble in amyl alcohol.
SUMMARY
In the following table we have simmiarized the results of our
tests together with those we have been able to find in the liter-
ature. Owing to the uncertainty of results obtained by use of
the older methods of testing for indol, only relatively recent work
has been included. The organisms are divided into two groups:
(I) those which may pretty definitely be regarded as giving
negative tests and (II) those for which positive results have
been reported. It should be noted that in every instance where
INDOL PEODUCTION BY BACTERIA 475
any considerable niunber of strains of an organism in group II
have been examined, negative as well as positive results have
been reported, with the exception of the cholera vibrio.
From this summary we must conclude that whereas the indol
test may serve as a valuable aid in differentiating bacteria, it
cannot be regarded as an absolute criterion. A positive test may
give definite information but a negative test must be interpreted
with caution.
We should also like to emphasize the necessity for a standard
reagent for the indol test and suggest the use of Ehrlich's
dimethylamidobenzaldehyde solution for this purpose.
In this table we have used the classification adopted by the
Society of American Bacteriologists (Winslow, 1920).
Group J. Indol negaiioe
Bcaillus anthracis* (Zipfel)
subtilis*
Actinomyces asteroides*
bo vis*
graminaris*
Bacterium abortum (Weeter)
cloacae (5 strains*, Kligler)
enteritidis (3 strains*, Crossonini, Porcher and Fanisset, Zipfel,
Nonnotte and Demanche)
fecalis-alcaligenes (3 strains*)
icteroides (Crossonini)
mucosum-capsulatum* (Hiss and Zinsser)
paratyphoeum A (2 strains*, Zipfel, Jordan, Nonnotte and Demanche)
paratyphosum B (13 strains*, Zipfel, Jordan, Nonnotte and Demanche)
pullorum (5 strains*, Mulsow)
rhinoscleromatis*
sanguinarium (Mulsow)
suipestifer (4 strains*, Zipfel, Crossonini)
typhosum (15 strains*, all investigators)
typhi-murium (Nonnotte and Demanche)
Clostridium botulinum (6 strains*)
chauvei*
Welchii*
Coiynebacterium Hoffmannii (3 stains*)
pseudodiphtheriae (4 strains*)
xerosis (2 strains*)
* Our tests.
476 JOHN F. NOBTON AND MABT V. SAWTEB
Diphtheroids (Malone)
Diploooccus pneumoniae (Jordan, Malone)
Eiythrobacillus miniaceus*
my coides-roseus *
mycoides-corallinus'*
prodigiosua (4 strains*, Crossonini, Zipfel)
Myobacterium leprae*
Moelleri (2 strains*)
tuberculosis (4 strains*, Zipfel)
Neisseria meningitidis (Jordan)
catarrhalis (Malone)
Pseudomonas cyanea*
cyanogenes*
violacea*
Pasteurella pestis* (Zipfel)
Btaphlococcus albus (8 strains*, Zipfel)
aureus (4 strains*, Zipfel)
citreus (Zipfel)
not specified (Jordan, Malone)
' Streptococcus yiridans (13 strains*, Jordan, MalontO
hemolyticus (2 strains*, Zipfel)
rheumaticus*
Sarcina lutea*
rosea*
Vibrio tyrogenus (Deneke)* (Zipfel, Tobey)
Zopfius Kopfii (3 strains*)
Sporothrix schenkii*
Blastomycetes dermatitidis*
Sao. pastorianus*
Group II. Indol positive or negcUive
Bacterium aerogenes* (Kligler, Chen and Rettger)t
coli* (Kligler, Chen and Rettger)t
dysenteriae* (Zipfel, Kolle and Wassermann)}
Clostridium sporogenes (edematis)* (Bertrand)
tetani (Hall)
* Corsmebacterium diphtheriae (Escallon, Zipfel)
Hemophilus influenzae (Rhein, Jordan, Malone)^
* Our tests.
t Chen and Rettger found 141 strains +, 306 — .
t Chen and Rettger found from feces 173 strains +> 0 — ; from soil 15 strains +
6-.
( We found as + Flexner, Hiss-Russel, Shiga, 110, 12 U. S., as - Hofifmanni,
177. Zipfel found Flezner andY +, Shiga — . Kolle and Wassermann giTe
Strong — .
± Rhein found 7 strains +, 1 — ; Jordan 18 +, 7 -^ ; Malone found 92 per cent
+, 8 per cent — .
INBOL PRODUCTION BY BACTERIA 477
Pasteurella aviseptica (Mulsow, KoUe and Wassennann)
Proteus group (Bengston, Horowitz, Kligler, Larson and Bell, Rhein, Sicre)
Pseudomonas pyooyanea* (Jordan) f
Vibrio cholerae (2 8train8^ Croesonini, Baudisch, Zipfel, Tobey)
finklerei (Crossonini, Tobey, Zipfel)
metschnikovi* (Crossonini, Steensma, Tobey)
protea*
^ Our tests.
T We found 13 strains — , 6 of them freshly isolated; Jordan reported both +
and — ; see also Lartigau (1898)
REFERENCES
«
Baudisch 1915 Uber eine neue Indolreaktion, Zeitschr. Physiol. Chem., 94,
132.
Benoston 1919 The proteus group. Jour. Infect. Dis., 84, 445.
Bbbtband 1913 Influence des regime alimentaire sur la formation de I'indol
dans 1 'organisms. Ann. Inst. Pasteur, 27, 76.
Cannon 1916 A simple and rapid indol test. Jour. Bact,, 1, 535.
Cbsn and Rbttosb 1920 A correlation study of the colon-aerogenes group
of bacteria, with special reference to the organisms occurring in the
soil. Jour. Bact., 5, 253.
Cbossonini 1910 Vher den Nachweis von Indol. Arch. Hyg., 72, 161.
Ehbuch 1901 Vher die Dimethyl-Amidobenzaldehyde Reaction. Berl. Med.
Wochensch., 1, 151
EscAiJiON 1908 Reserche de Tindol dans les cultures microbiennes a I'aide du
'furfural. Compt. rend. soc. biol., 66, 507.
FiscHEB 1915 Hemmung der Indolbildung bei Bact. coli in Kulturen mit
Zuckerzusats. Biochem. Zeitschr., 70, 105.
Hall 1920 Unpublished communication.
Hiss and Zinssbb 1917 Textbook of Bacteriology.
HoMBB 1916 A suggestion as to the cause of lessened production of indol in
media containing glucose. Jour. Hygiene, 16, 401.
HoBowiTZ 1916 Contribution a I'^tude du genre Proteus Vulgaris. Ann.
Inst. Pasteur, 80, 307.
JoBDAN 1899 Bacillus pyocyaneus and its pigments. Jour. Exp. Med., 4, 627.
JoBDAN 1^17 Differentiation of the paratyphoid-enteriditis group I. Jour.
Infect. Dis., 20, 7.
JoBDAN 1919 Production of indol by strains of Pfeiffer's bacilli. Jour. Am.
Med. Assn., 72, 1542.
JoBDAN 1920 Biology of the Pfeiffer bacillus. Am. Jour. Pub. Health, 10, 648.
Klzgleb 1914 Observation on indol production in the Colon-typhoid group.
Jour. Infect. Dis., 14, 81.
KoLLB AND Wassxbmann 1913 Haudb. d. pathogen. Mikroorganismen.
478 JOHN p. NOKTON AND MABT V. SAWYER
Larbon and Bbll 1913 A study of the lesions produced by Bacillus pToteni.
Jour. Infect. Dis., IS, 510.
Labtigau 1898 Epidemic dysentery caused by Bacillus pyocyaneus. Jour.
Exp. Med., 8, 604.
LooHBM AND LoGHEM-Pouw. 1012 BeitrSgc sur Differensierung des Proietu
Groupe. Centrabl. Bakt., Orig., I. Abt., 66 , 19.
LooiB 1920 Synthesis of tryptophane by certain bacteria and the nature of
indol formation. Jour. Path, and Bact., 28, 224.
Malons 1920 The production of indol by Pfeififer's bacillus. Indian Jour.
Med. Res., 7, 519.
MuLsow 1919 Avian paratyphoid bacilli. Jour. Infect. Dis., 26, 135.
NxLBON 1916 Some color reactions for indole and scatole. Jour. Biol. Chem.,
24,527.
Nqnnottb and Dkmanchb 1908 Sur la recherche de Tindol dans les eoltuni
microbiennes. Compt. rend. soc. biol., 64, 658.
PoBCHBB 1911 Les diverses peptone et la formation de I'indol. Compt. rend.
soc. biol., 70, 464.
PoBCHBB and Panibbbt 1909 Indol dans les bouillons microbiens. La presence
dans las cultures du cholera des pbules. Compt. rend. soc. bid, tt,
624.
PoBCHBB AND Panibbbt 1911 La formation de I'indol dans les cultures en
milien aerobes et en milien anaerobes. Compt. rend, soc^ biol., 70, 43S.
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soc. biol., 82, 138.
RxYAB 1912 Studies on indol. Centralbl. Bakt., Orig., I. Abt., 68, 547.
Riybbb 1920 Indol test on the spinal fluid for rapid diagnosis of influenial
meningitis. J. Am. Med. Assn., 75, 1495.
SiCBB 1909 Sur la reserche de I'indol dans les cultures microbiennes a i'&ide
des nouveaux rSactife. Compt. rend. soc. biol., 67, 76.
Stbbnbma 1906 tJber den Nachweis von Indol und die Bildung von Indol
vortausehenden Soffen in Bakterien Kulturen. Centralbl. Bakt.,
Orig., I. Abt., 41, 295.
ToBBT 1906 Cholera red and indol reaction. Jour. Med. Res., 16, 305.
Wbbtbr 1920 Unpublished communication.
ZiPFBL 1913 Weitere Beitrage sur Kenntniss der Indolreaktion. Centralbl
Bakt., Orig., I. Abt., 67, 583.
WiNBLOW AND OTHBB8 1920 The Families and Genera of the Bacteria. Jour.
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ON NITRIFICATION
IV. THE CARBON AND NITROGEN RELATIONS OF THE NITRITE
FERMENT
AUGUSTO BONAZZI
Contribution from the Laboratory of SoU Biology of the Ohio Agricultural Experi-
ment Station, Wooeter, Ohio
Received for publication, January 21, 1921
Winogradsky (1890) showed that the organism of nitroso-
fermentation is capable of growing in a medium completely void
of fixed organic matter when in presence of ordinary air. He
proved, thereby, that the organism must derive its carbon from
one or all of the following sources; the mineral carbonates, thjs
free carbon dioxide, or the volatile organic compounds of the
atmosphere.
That a source of carbon is found and utilized by the organism
is supported by the fact that analysis of the culture liquid after
nitrosofermentation has taken place shows it to contain an
appreciably greater quantity of carbon than it did before the
fermentation was activated by inoculation.
Godlewsky (1892, 1895) as well as Winogradsky and Omeli-
ansky (1899), found that cultures of nitrite and nitrate-forming
organisms lacking free or combined carbon dioxide could not
develop. In discussing the experiments of Winogradsky, above
referred to, Beijerinck (1903), points to the possibility that the
carbon was not fixed by the cells but by the magnesium oxide
present in the basic carbonate used by this investigator. If
this criticism were true it is hard to understand why the ratio
of "nitrogen nitrified" to "carbon assimilated" should be a
constant value. It might be assumed that the results of Ashby
(1907-8), (soon to be related) could support Beijerinck's hypothe-
sis, but close scrutiny shows them to bear a different significance.
470
JOUBXAL or BJLOTBBIOLOOT, TOL. TX, NO. 6
480 AUGUSTO BONAZZI
It appears, therefore, that the function of nitrosofennentation
is closely and intimately connected with the function of carbon
assimilation by the bacterial cells. In fact, from the data at
oiur disposal it appears as if their separation were impossible.
Loew (1891) as early as 1891, soon after the classical researches of
Winogradsky, advanced the view that the process of nitroso-
fennentation does not take place according to the path described
in the accompanying equation :
2 NH, + 30, — 2N0,H + 2H2O
but rather by the path symbolized as follows:
2 NH, + 26, -> 2NO2H + 4H
The hydrogen liberated during the reaction is not found free in
the medium but is momentarily formed in the ceUs and utilized
in a synthetic process according to the following equation:
CO, + 4 H -^ CH,0 + H,0
The resulting formaldehyde is not condensed into carbohydrate
but directly into protein substances. The fact that nitrates are
not utilized by the organism is cited by Loew in support of the
above view.
From a physiological standpoint the question is an important
one, and a full understanding of its "modua operandi^' will lead
to an understanding of the formation of the oxidized nitro-
genous compoimds in nature and of the early phases of the
accmnulation of the carbon supplies on the earth.
EXPERIMENTAL
It was at first necessary to establish whether the organism
from American soils behaved towards carbon dioxide in a manner
similar to that of the organisms from Europe and Asia, since the
differences in form and life-cycle shown by these different organ-
isms could well be accompanied by differences in physiological
characteristics. With this aim in view, in 1914 a soil which had
received the application of 9000 pounds of calcium carbonate
ON NITRIFICATION
481
per acre was used. Three 100 gram lots in the air-dry condition
were each moistened with 20 cc. of a 0.5 per cent solution of
ammoniimi sulphate and incubated at room temperature under
the following conditions: no. 1, together with a beaker of water,
under a bell-jar sealed with vaseline to a glass plate; no. 2, under
a bell-jar together with a beaker of soda-lime; no. 3, in the open
laboratory air. After thirty days the soils were extracted with
water, and the nitrates determined in the extract by means of
the phenoldisulphonic acid method. The results obtained are
summarized in table 1.
TABLE 1
NUM-
COITDITION or ATMOSPHBBI
MITBOOBir AM WITBATM
PBB KILO or eon.
BBB
At the
•tftrt
At the
end
Formed
1
Natural but limited
mam.
15
15
15
infill*
168
58
125
153
2
Carbon dioxide removed
43
3
Natural open
110
It thus appears that the process of nitrification in American
soils is appreciably hindered by the removal of the free carbon
dioxide. At first it would seem as if these results were contrary
to those given by Godlewsky, since even in presence of soda lime
a certain amoimt of nitrification did take place. Nevertheless,
the arrangement of the experiment may account for this. The
soil was in Erlenmeyer flasks and the bell-jars used were of 5000
cc. capacity. Had the soda-lime been in the immediate vicinity
of the soil; the carbon dioxide removal would have been more
complete. Furthermore, in a soil containing organic matter,
decompositions are always taking place, and by virtue of the
great surface and high retentive power of soils for gases, enough
carbon dioxide may easily have been retained to furnish a source
of this gas in the immediate vicinity of the bacterial cells. Using
the ratio N/C = 36 established by Winogradsky, the quantity
of carbon fixed in the nitrification of 4.3 mgm. of nitrogen, would
be 0.1 mgm. a quantity easily retained by the soil.
482 AuausTo bonazzi
Indications are, theref ore, that the organism of nitrosofermen-
tation acting in the soils with which the present work was under-
taken, behaves towards free carbon dioxide in a manner similar
to the organisms with which Winogradsky and Godlewsky were
working. Additional proof on this point is furnished by experi-
ments in solutions in which the above disturbing factors were
eliminated.
Experiment 244
In each of two large flat bottomed Fembach flasks were placed
50 cc. of the ordinary Omeliansky solution, and both were inocu-
lated with an active cultiu'e of Nitrosococcus from Wooster soil,
in equal amounts. One was incubated with no additional treat-
ment while a small container of concentrated potassium hy-
droxide was placed in the neck of the other and the flasksealed with
a manometer tube so as to avoid negative pressures in the system.
After incubation at 25^0. for fifteen days the following results
were obtained.
TABLES
KUMBBB
niATMSNT
NITBITB
FOBMED
1
Nonnal air •. . . .
16.96
2
Air minus COi
0.41
There is evidently no doubt that the organisms acting in
Wooster soil are physiologically similar to those acting in
European soils.
A system containing the ordinary Omeliansky solution for
nitrite formation from ammonium sulphate, and magnesium
carbonate as a base, derives its free carbon dio:pde from various
sources.
The interaction of the nitrogen and carbon sources, as they are
added, leads according to equation I, to the formation of COs.
By the process of nitrification itself, according to equation II,
more free COs is formed, while the atmospheric carbon dioxide
ON NITRIFICATION 483
constitutes a source that for convenience shall be here named
III. It is then, possible that, like all other organisms, the
Nitrosococcus undergoes processes of anabolism and catabolism,
in the latter probably giving off carbon dioxide by respiration:
this source shall be here named lY.
1. MgCO, + (NHOa SO4 ^ MgS04 + (NHO, CO, /. NHs +
H2CO. + H2O + CO,
II. MgCO, + 2HN0, -► Mg (NOO2 + H,CO, .*.
H2O + go,
Duclaux (1896) expressed the opinion, based upon the results
of the work of Winogradsky and of Godlewsky, that if the organ-
isms were not capable of utilizing the carbon of the carbonate
this could be due to the fact that some difference might exist
between the carbon dioxide of the atmosphere and that arising
from equations I and II above. One point should nevertheless^
be mentioned as a criticism of this view i. e., that by allowing the
carbon dioxide absorbant to be contuxuaUy present in the system
(as was done by Godlewsky and in the above experiments dupli-
cating his work), the action of the bacteria will be dependent not
on the quality of the gas but on the velocity of distillation of the
latter from solution. With very large surfaces of the culture
solutions and relatively large surfaces of the absorbent, the
CO2 tension in the gaseous phase of the system will be so slight
that the organisms will not be in position to utilize the very
slight traces temporarily to be found in the solution, before they
are removed from contact with them.
The question therefore becomes a twofold one: the organism
of nitrosof ermentation apparently cannot develop in the absence
of all traces of gaseous carbon dioxide, yet is able to develop in
media free of all traces of fixed organic carbon as was shown by
Winogradsky (unless the traces carried in the inoculum may be
considered as sufficient to vitiate the results, a conclusion hardly
justified in view of the care with which the author attempted to
avoid this a priori objection).
484
AUGUSTO BONAZZI
But the question of the growth of the nitrosof erment in an
environment only initially free of carbon dioxide is as yet an
open one. In order to answer the theoretical question advanced
by Duclaux, cultures in full nitrification are best, adapted,
since in these the COr-production from equations I and II is con-
siderable.
a, Soda lixpe; h, furnace at 900-1000*^0.; c, soda lime; d-e, coneentrated KOH;
f, soda lime; g, stop-cock; k, culture chamber; i, Hg. manometer.
Experiment 200
•
An apparatus prepared as is shown in figure 1.
The culture was in full nitrification when used and the experi-
ment was started by aerating the flask for two and one-half
hours, with air freed of COs by passing through the train shown
above. After aeration stopcock g was closed and the flask was
incubated on a clinostat (Bonazzi, 1919 b). The quantities (A
nitrite formed before and after the treatment are given in table 3.
TABLE 8
N ITBITB KITBOOni FOBMSO HT 100 OC.
OP BOLtnON DUSINO THS
Five d*yi of
preparation
Two days
preriousto
treatment
Three dayicl
treatflBtnt
Total
47.79
11.94
32.50
16.25
9.20
Formed per day
3.07
Experiment 229 and 229a
The apparatus used in these experiments were such that no
negative pressures could obtain in the culture systems; the
aeration train was similar to the one used in experiment 200,
ON NITRIFICATION
485
with the omission of the furnace. The manometer of the previous
experiment was also replaced by a paraffin-oil manometer guarded
from the external carbon dioxide by a soda lime tube. A barium
hydroxide bulb was placed between the culture flask and the
suction pump to allow the detection of even small traces of
CO,. Aeration was carried out for two hours durmg which time
the flasks were often shaken. After aeration, the bulb of
Ba(OH)s was inserted and aeration continued for one half hour
more during which time the hydroxide showed no turbidity.
The residts of these experiments are given in table 4 in which is
also given the activity of the cultures in the period of preparation.
TABLE 4
XJCPBRIllBlfT 229
■XPBBXMSMT 229 A
Nitrogen transformed to nitrite during
Two days
previous to
treatment
Seven days of
treatment
Twodasm
previous to
treatment
Five dasrs of
treatment
Total
mgm.
8.44
4.22
mom.
18.66
2.67
mgrn,
11.33
5.56
mffm.
19.72
Formed per day
3.94
It appears therefore that nitrification takes place normally at
the expense of the carbon dioxide formed by the reactions in the
culture medium and that therefore it must be assumed that the
suggestion of Duclaux was based upon facts which could not well
be utilized in the formulation of the hypothesis.
As may be seen, the cultures here used were in full and inten-
sive nitrosofermentation and the carbon sources varied. Yet
owing to the specific arrangement of the experiments, there
should be a possibility of separating the supplies at their point
of formation. In fact, if a very small inoculum were used in
place of the very great ones used in the previous experiments,
it should be possible to diminish appreciably if not to stop com-
pletely the formation of the supplies due to equation II. This
was done in experiment 227-a.
486 AUGUSTO BONAZZI
Experiment 2£7-a
The apparatus used were made up accordii^ to figure 2.
Aeration was carried on for about one hour and the complete
absence of COi ascertained by means of the bariimi hydroxide
bulb.' The medium used was ignited and sterilized compost,
moistened with sterile Omeliansky solution in the proportion
of 40 cc. for each 100 gram of soil. One gram of basic MgCOi
had been placed in each flask, while dry, before sterilization.
ei b cf
Fig. 2
a. Concentrated N&OH;b, soda lime; c, soda lime; d, paraffin oil seal ;e, culton
chamber with culture in — m; /, crucible with appropriate solution; g, Ba{OH)t
guard for detecting COi; h, paraffin seals.
All flasks were inoculated with a soil suspension which contained
negligible amounts of nitric or nitrous nitrogen. After inocula-
tion, the cotton plugs were removed, the flasks placed under the
bell jars, the seal made by pouring melted paraffin at the contact
of jar and plate and aeration started. ■ The arrangement of the
flasks was the following:
No. 1. Check uninoculated.
No. 2. Air in system freed only of the initial COi.
No. 3. Air freed of COi throughout, containing NaOH 50
per cent.
No. 4. Air containing only the COj developing from the
reaction of 5 mgm. NaiCOg and an excess of H1SO4 takii^ place
in/.
ON NITRIFICATION
487
No. 5. Air with no change in composition (natural).
After thirty days incubation at 25°C. the nitrates
extracted, and determined by reduction and distillation,
results are given in table 5.
were
The
TABLE 5
IfUUBXB
1
2
3
4
5
TBBATMBMT
Check
NoCX)iat start....
No COi throughout
COs added
Natural air
NHi - Nfl
AT THB XKD
mtfm,
■ • • •
8.77
9.75
0.00
0.07
N| NXTBIFIBD
mgm,
• • • •
1.28
0.44
8.26
14.57
System no. 4 requires a little discussion. Sulphuric acid was
added in excess of the quantity needed for the neutralization of
the NasCOs, and apparently its action has been to absorb the
ammonia which was distilling from the culture itself; the final
nitrite content could be but low. It should also be stated that
no attempt was made to recover all the residual ammonia in the
soil. The quantity of nitrate formed in no. 3, if not accoimtable
by an experimental error in analysis, would require, according to
the ratio established by Winogradsky, a quantity of 0.01 mgm.
of carbon as COj, a quantity which could easily have escaped
immediate absorption by the alkali used.
The conclusions to be drawn from these experiments are,
then : (a) that nitrification is completely checked by the complete
absence of carbon dioxide in the system throughout the experi-
mental period (when a concentrated alkali is present therein);
(b) that when a small inoculum is used, in spite of the fact that
ignited soil holds carbon dioxide by absorption, and when the
supply of this gas is nil at the start, the phenomenon of nitroso-
fermentation is practically inhibited.
In direct consequence of these facts stands the conclusion that,
since the inoculum was small and nitrification in no. 2 was negli-
gible, contrary to the results of experiments 229 and 229a, and
since in this case there was not an active production of carbon
488 AUGXJSTO BONAZZI
dioxide by virtue of equation II, the latter source of the gas
appears to be the one most active in furthering nitrification. This
is probably attributable to the fact that it is directly connected
with the life activities of the organism concerned.
The supply due to reaction I is, therefore, slowly utilised,
probably because very rapidly distilled from the immediate
surroundings of the cells; or a molecular rearrangement of the
basic carbonate used may take place. These considerations
would then place the process of nitrification dependent upon and
secondary to the process of carbon assimilation. We shall have
occasion to return to this point later in this paper.
According to Warington, nitrification • of ammonia can take
place only with ammoniimi carbonate, and the function of the
carbonated base is to furnish that compound by reaction with
other ammonium salts. Ashby found nitrification to take place
in presence of ferric hydrate to a considerable extent, and also
some nitrification of the ammonia absorbed by modeling clay
alone (1907-1908).
Hopkins and Whiting (1916) also claim that nitrification will
take place in presence of tri-calcium phosphate as a neutralizing
substance. It is evident that in the experiments of the last
named investigators ammonium carbonate could not be formed
by reaction between the neutralizing base and the source of
nitrogen, a fact that throws a doubt on Warington's assumption.
The reaction leading to the formation of ammonium carbonate
should then be directly connected with the nitrogen nutrition of
the organism of nitrosofermentation rather than with the
carbon nutrition. The question of the autotrophy and hetero-
trophy of the organisms is also intimately connected with these
observations.
If it were possible to avoid, in a culture, reactions I and II,
a step would be taken towards the understanding of the phenom-
enon that Winogradsky named, " chlorophyllic action without
chlorophyll". The aim could be approached either by the use
of a non-carbonated base or by allowing nitrification of the
ammoniacal nitrogen in the form of hydroxide. Experiments
in the hope that the second of these two assimoiptions might prove
ON NITRIFICATION 489
practical failed to give satisfaction. In presence of MgCOs.
Mg (OH)s as a neutralizing base, ammonium hydroxide added
in small amounts at a time was easily volatilized and removed
from the nitrifying system : only 7 mgm. of nitrogen were trans-
formed to nitrite in eleven days although 30 mgm. of nitrogen as
ammonivun hydroxide were added during this period, in small
amounts ranging from 2 to. 9.4 mgm. at one time. This source
of ammonia even though imdergoing slow nitrification did not
seem to hinder the action of the organisms, since the same culture
which had received the hydroxide additions was capable, after
this treatment, of nitrifjdng in th^ee days 2 cc. of a 10 per cent
solution of ammonium sulphate for every 100 cc. of culture
solution.
Although the results obtained pointed to the possibility of
nitrification of ammonium hydroxide, it was thought that a study
of a non-carbonated base to be used in the cultures would prove
more satisfactory.. Magnesium oxide was chosen since it has
a lower solubility of the carbonate and would give results directly
comparable to the conditions existing in the ordinary culture
solution as used in the present paper. Calcium oxide and
hydroxides as well as the oxides and hydroxides of the other metals
were discarded a priori on account of their greater solubility and
greater alkalinity. The aim was to use a base that would serve
to neutralize the acids arising from the reactions taking place
during nitrification rather than to exert its physiologically
alkaline properties. That the oxide chosen is not toxic is to be
assumed from the fact that the carbonate, used in all the pre-
vious experiments, contained one molecule of the oxide for
every molecule of the carbonate.
Experiment £S4
Six flasks with very large flat bottoms received 50 cc. of the
ordinary Omeliansky solution made up with tap water. After
sterilizing and coolmg, flasks 1, 2 and 3 received the addition
of a sterile suspension of Mg COt. Mg (OH)s, while flasks 4,
5 and 6 received a sterile suspension of MgO. All except nos.
490
AUGUBTO BONAZZI
TABLE 6
MUlf-
BSB
•
BlM
1
MgCOi
2
MgCO,
3
MgCO.
4
MgO
5
MgO
6
MgO
TBBATMXIIT
Inooulation
Check uninoculated. . .
Inoculated
Inoculated
Check uninoculated . . .
Inoculated
Inoculated
BBACnOH
Nine day*
NHt
0
0
NsOi
0
0
1
Thirteen diyi
NHi
NaOi
0
1
+
1 and 4 were inoculated with an active culture of the nitrite
ferment and incubated at 25^C. Tests made at various inter-
vals yielded the results given in table 6 where 0 signifies a nega-
tive result and l^ +y n positive results of increasing intensity.
On a short period of incubation, although free atmospheric
carbon dioxide was in contact with the solutions no appreciable
nitrification took place, when magnesium oxide was used, while
nitrification was active in the presence of the carbonate.
Experiment Slfi
The above cultures in which no appreciable nitrification took
place (nos. 4, 5, 6) were each divided into two equal portions by
means of sterile pipettes and placed, without reinoculation, in
sterile flasks of equal diameter. One portion, left as control,
received no addition whereas the other portions received various
treatments, as is shown in table 7.
TABLE?
XUICBBR
4
5
51
6
61
TBBATMBirr
Check uninoculated
(NH4)tS04 and MgO
(NH4)iS04 and MgO and MgCO,
(NH4)^04 and MgO and (NH4),C0«
(NH4)iS04 and MgO, (NH4)iC0t and MgCO,
NITROOBN AM
•
MITBITB AITBB
POTAL
SBCOND
AlOfOinA
PBBIOD OF
BBACnOX
ZZrCUBATION
ei^es.
0.77
s
6.22
r
4.85
?
2.50
+
2.35
«
ON NITRIFICATION 491
The results obtained in this, the second, period of incubation
are striking. Ammonium sulphate will be nitrified, although
slowly, in the presence of a non-carbonated base, the difference
in the results of experiments 234 and 240 being due to the time
factor. The lag in nitrite formation in cultures 51, 6 and 61
may be explained in either of two ways: (a) distillation of the
ammonium carbonate, and (b) retarding effect of this compound
with subsequent volatilization of considerable quantities of
ammonia. In fact in the cultures 6 and 61 a concentration of
ammonium carbonate was used such as to give 28 mgm. of
nitrogen in 25 cc. of solution, a quantity twice as great as that
of the ordinary Omeliansky solution.
The results relating to the nitrification in the presence of a
non-carbonated base are then in accord with the findings of
Ashby and of Hopkins and Whiting and it is possible that the
atmospheric carbon dioxide, here, played an important r61e in
the process of nitrification. That anmionium carbonate is
nitrifiable as such should be assumed from the work of Warington,
but additional proof is furnished by experiments here to be
related.
Experiment 2J^1
Fifty cubic centimeters of Omeliansky solution from which
the ammonia source was omitted, were sterilized in 750 cc.
Erlenmeyer flasks. After cooling they received sterile magne-
sium carbonate suspension or magnesium oxide and either 1
cc. of a sterile 10 per cent ammonium sulphate solution or 0.5
cc. of a 17.2 per cent ammonium carbonate^ solution pasteurized
at 60^C.
The arrangement of the experiments^ and the results obta^Ied
are given in table 8.
^ The carbonate used in all these experiments "was a mixture of the normal
carbonate and the carbamate of the following empirical formula: (NH4)sC0|.
NH4COJNH,.
' The term capped in this and other experiments refers to the mercury or
paraffin oil seals used in order to avoid the escape of volatile substances from the
nitrifying systems. Their efficiency may be noticed by a comparison of the
results obtained in nos. 3 and 4 of table 8.
492
AUGUSTO BONAZZI
TABLE 8
KUM-
1
2
3
4
5
6
7
TBXATMSNT
(NH4)iS04 and MgCOt open. . .
(NH4)sS04 and MgCOg capped.
(NH4)iC0, open
(NH4)jC0« capped
(NH4)sCOs and MgCOt capped
(NH4)sCOs and MgO capped...
(NH4)iC0t and MgO capped...
BBACTIOlf ATTEK
10 days
10 days
1
»
0
0
+
m
1
»
0
1
0
0
0
0
vmrtE
NITBOOSjr
FOCnSD ATFES
81 DATS
mgm.
12.25
4.44
6.47
20.62
13.12
0.75
0.78
In no. 2 nitrification was, for some unknown reason, retarded,
for, even after nineteen days no nitrite formation had taken place,
so that the quantity found after thirty-one days was formed
during the last twelve days of incubation. The action of the
magnesium oxide on the nitrification of ammonium carbonate
is a retarding one and this may be due to physical reasons.
Distillation of the ammonia from the neutral or slightly acid
solution takes place at a relatively fast rate, as is shown in no.
3 and in a solution made alkaline by the addition of MgO the
distillation is too fast to allow any competition by the bacterial
cells.
Since it is evident from these experiments that the ammonium
carbonate can be utilized by the nitrosoferment even in the
absence of a base, a study of the nitrification of this substance
in the presence or absence of atmospheric carbon dioxide will
lead to a better imderstanding of the fimction of the magnesium
carbonate in the cultures undergoing nitrification. Besides,
if ammonium carbonate were nitrified in the absence of atmos-
pheric carbon dioxide it would be evident that this nitrogenous
carbonated substance could furnish the carbon necessary for
the life of the organism. The latter condition would also
indicate the mode of action of the compound.
ON NITRIFICATION
493
Experiment £44
A solution prepared as follows: sodium chloride 1 gram; dipo-
tassium phosphate 0.5 gram; hydrated magnesium sulphate
0.51 gram; hydrated ferrous sulphate 0.364 gram; distilled water
500 cc. Fifty cubic centimeter portions pipetted into six large
flat-bottomed Fembach flasks fitted with paraffin oil seals.
After sterilization flasks 1, 2 and 3 received sterile MgCOs.
Mg (OH)i and 1 cc. of a sterile 10 per cent (NH4)2S04 solution,
while nos. 4, 5 and 6 received only .1.5 cc. of a 6.75 per cent
pasteurized solution of ammonium carbonate. Subsequently all
were inoculated. Flasks 2 and 5 received a small container of
concentrated KOH in the neck while flasks 3 and 6 were washed
free of all carbon dioxide by aeration for one hour, the air issuing
from the flasks at the end of this time causing no turbidity in
Ba(0H)2 when passed through it. Inoculation was made with
an active culture of Nitrosococcus, and incubation was at 25°C.
for fifteen days. Analysis of the cultures after this period gave
the results presented in titble 9.
TABLES
NUMBKB
1
2
3
4
5
6
TBBATliSm
H8COsand(NH4)t804
Nonnal air
COi removed throughout experiment. .
Only the initial COs removed
(NH4)tC0t.NH4C0iNHt
Normal air
COt removed throughout experiment. .
Only initial COt removed
KmjTM
MITBOOUr
FOUND AT THB
Kfoor
IMCUBATIOir
FKBXOD
tItQtHm
16.98
0.41
8.76
7.17
0.47
8.59
Experiment 246
Erlenmeyer flasks of 750 cc. capacity were used with mercury
seals, and 50 cc. of the solution used in the previous experiment.
After sterilization, 1 cc. of the pasteurized solution of ammonium
494
ATJGUSTO BONAZZI
carbonate used in experiment 244 was pipetted in each flask and,
after inoculation, a container with concentrated KOH was
placed in the necks of nos. 1 and 2. After incubation at 25°C.
the solutions submitted to analysis gave the following results
(table 10).
TABLE 10
KUMBKR
1
2
3
4
TRXATMSMT
All COs removed throughout experiment
All COs removed throughout experiment
Natural stagnant air
Natural stagnant air
mrsiTB
KITBOOKSr
FOUITD AVni
KKD <nr
I19CT7BATI09
PKBIOD
0.13
0.38
7.52
6.24
Repetition of this experiment (experiment 249) yielded the
results given in table 11.
TABLE 11
NUICBKB
•
TBBATMBZrr
VITBITB
MXTBOOSy
POUKDAT7HI
mmor
IMCUBATIOK
PBBIOD
1
All COt removed throughout experiment
mom.
0.35
2
Natural stagnant air
16.63
DIBCXJ8SI0N AND CONCLUSIONS
From the foregoing experiments the following considerations
seem justified.
In the solution containing ammonium sulphate and magnesium
carbonate removal of all traces of carbon dioxide causes nitroso-
fermentation to come to a standstill, whereas if only the carbon
dioxide present at the start be removed but that developing
through reactions I and II (given on page 483) be allowed to accu-
mulate in the systems nitrosof ermentation could continue in a ratio
roughly proportional to the size of the inoculum. In fact, even
with a very small inoculum some nitrification could be detected.
ON NITRIFICATION 495
It should be assumed, therefore, that the carbon dioxide formed
through these reactions can go to replace that removed at the
start; the COs tension in the liquid and gaseous phase soon
approaching that state of equilibrium which is favorable to the
action of the nitrite-forming bacteria. In the presence of KOH,
or other CO2 absorbent, these reactions are taking place, but the
gaseous products formed in relatively small quantities are soon
removed by the absorbent, the resulting CO2 tension in the cul-
ture solution reaching the point where the normal activity of
the organism is impossible. Under such conditions it is even
to be doubted whether anunonimn carbonate is formed as such
and not immediately hydrolyzed and the products of hydrolysis
distilled from reach of the cells before completion of the synthetic
step in the reaction. This is evidenced by the fact that when
Omeliansky solution containing ammonium carbonate as the
source of nitrogen is exposed to a concentrated alkali in a closed
system it rapidly changes from an acid reaction, to phenolphtha-
lein, to a strongly alkaline reaction. If ammoniiun sulphate
be the source of nitrogen and magnesimn carbonate be added to
the solution, the final result is the same, a very strong alkalinity
being developed where at first only a weak one could be detected.
In the tables reported above it is evident that such conditions
lead to a check on the process of nitrification. The carbonate-
carbamate used in view of the hsrpothesis of Chodat under the
above conditions of COj removal did not lead to a nitrogen
hunger. This is proved by the fact that a solution containing
this compound, and incubated in a system in which KOH was
present, contained after the incubation considerable quantities of
ammonia as determined by the Nessler reagent, while a heavy
precipitate was obtained by allowing a drop or two of the culture
solution thus incubated to react with Ba (OH)s. Some carbonate
as such was therefore still in solution.
These last considerations lead to the conclusion that it is the
carbon dioxide as such that is necessary to the organisms of
nitrosofermentation and that it can be utilized only when the
tension of this gas is above a minimum limit. Thus the nitrogen
nutrition of the organism is closely related and in fact completely
496
AUatJSTO BONAZZI
dependent upon its carbon nutrition. The free carbon
dioxide is not only necessary for growth but is also necessary
for the performance of the normal oxidative functions peculiar to
the cells. Therefore nitrosofermentation which is supposed
to furnish the energy for the carbon assimilation can not even
be established in the absence of free carbon dioxide. The
small quantity of nitrite formation in the presence of KOH, if
positive at all, must be considered as the result of an autooxi-
dation of the cells themselves and a utilization of the energy
thus liberated, for the process of nitrite formation, a proce^
which soon comes to a standstill because of the strong negative
pressure of the CO2 outside the cell and of the subsequent
diffusion of the intracellular material towards the outside, and
also because of the strong alkalinity developed in the medium.
(nitrification)
(respiratior|)
Fig. 8
This interpretation leads to a special conception of the life of
the organisms of nitrosofermentation. When the optimmn car-
bon dioxide tension is existent, the cells, during their life cycle,
perform two synchronous functions; one of ceUular respira-
tion and one of carbon assimilation, the f onner serving for the
initiation of the process of nitrosofermentation and subsequent
ON NITRIFICATION 497
carbon assimilation by the second. Expressing these functions
by means of a diagrammatic representation, figure 3 is obtained.
According to the above diagram, when the cell carbon is suffi-
ciently large the process of chemosynthesis is endless, unless one
of the end products is removed. Thus in the case of narcosis
of the cell, respiration continues with degeneration and complete
consumption of the available cell carbon, and when all such were
consumed death of the cell would result. This condition of nar-
cosis may be brought about by an excessive concentration of food
substances or of cellular byproducts, with the cellular breakdown
demonstrated by Bonazzi (1919-a) and by Gibbs (1919) and
physiological inertia as has been shown by Boullanger and
Massol (1903, 1904).
When the supply of free carbon dioxide is nil throughout the
experiment the respiration process regulates chemosynthesis and
the products of nitrosofermentation are in immediate relation
to the quantity of cell substance respired and, since no carbon
assimilation can follow, death of the cells results.
When ammonium carbonate is used as a source of carbon and
the free carbon dioxide is continually removed by means of an
absorbent there is a slow accimiulation of the carbamate and
fast removal of the ionized COs (Macleod and Haskins 1906).
Together with this there is a depletion of all the respirable stores
in the cell, so that in the system the following substances will be
found: (NHOiCOg, NH4CO2NH2, cells, traces of respired C
compounds, and NHa. Since it has been experimentally proved
that the cells cannot, under these conditions, assimilate this
nitrogen (experiment 244, 246 and 249) the interpretation to
be given to these facts is that the free carbon dioxide is closely
tied up with the nitrogen nutrition of the organism and that in
this condition it distills too fast for the cells to utilize it. It
follows that if this distillation is prevented by mechanical means,
there should then be possible some nitrification and chemosyn-
thesis: this is what actually takes place in experiments fulfilling
the required conditions.'
* Meyerhoff in PflQger's Arekiv f . Ges. Physiol. 1917. 166, 240-280, found
nitrification to proceed in the presence of 10 per cent NaOH solution, and the
498 AUOUSTO BONAZZI
The results obtained by the use of ammonium carbonate as
a source of nitrogen and carbon, as well as those obtained with
a non-carbonated base emphasize the fact that it is the free
COs that is utilized by the cells, a view substantially corrobo-
rated by the findings of Ashby and of Hopkins and Whiting
reported above.
This free carbon dioxide is not necessary for the formation of
ammonimn carbonate, but for another piupose: chemosynthesis.
The oxidation of ammonia is to be considered as taking place
in two steps: (a) one of respiration with resultant gain in energy
and synchronous nitrogen absorption, (b) the other of nitrogen
assimilation (nitrification prpper) whereby oxidation of the ab-
sorbed nitrogen takes place, the utilized portion going to make up
the following cell generations, nitrous acid is split off and excreted
as a non-utilizable product, and energy is liberated. There-
fore, if the free carbon dioxide were removed from a culture
containing both ammonium carbonate, as a nitrogenous source,
and large numbers of bacterial cells, respiration should be great
enough to allow some nitrification to take place. If, on the
other hand, the number of active cells were limited, nitrification
would come to a standstill before a quantity of nitrites were
formed detectable by the ordinary chemical means. Experimen-
tal evidence bears proof of the correctness of the above
hjrpothesis.
ST7MMART
This paper reports a study of the functions of autotrophic
carbon assimilation and nitrogen nutrition of the nitrosof erment.
These functions are f oimd to be intimately connected and mutu-
ally interdependent, the bacterial cell being xmable to assimilate
the abundant stores of nitrogen in a nutritive solution in the
absence of ''free" carbon dioxide, even though a carbonate
as such, be present, in the medimn. Consequently on the
presence of this "free" carbon dioxide is dependent the process
present author found nitrification to proceed when the tube containing ooncen-
trated KOH was placed very near the mouth of the flask so that free circulation
of the air was interfered with.
ON NIISIIFICATION 499
of nitrogen oxidation which follows the absorption and leads to
the formation of nitrous acid and its salts.
REFERENCES
Abhbt 1907-1908 Jour. Agric. Sci. (Cambridge) 2, 52-^7.
BiEjsBiNCX AND Van Dslden 1903 Centr. f. Bakter., 2 Abt., 10, 33-67.
BoNAzzi 1919a Botan. Gazette, 68, 194-207.
BoNAZzi 1919b Jour. Bact., 4, 43-69.
BouLLANQEB ANB Mabsol 1903 Aimales d. I'lufititut Pasteur, 17, 492-515.
Boi7LLANGSB AND Massol 1904 Azinales d. I'lnstitut Pasteur, 18, 181-196.
DiTCLAXTX 1896 Annales de Tlnstitut Pasteur, 10, 414-416.
GiBBS 1919 Soil Science, 8, 427-471.
GoDLEwsKT * 1892 Bull. Intern. Acad. Scie. Cracovie, 408-417.
GoDLEWBKT 1895 Bull. Intern. Acad. Scie. Cracovie, 178-192.
Hopkins and Whitino 1916 Bull. 190, Illinois Agric. Exper. Stat., 395-406.
LoBW 1891 Botan. Central, 46, 222-223.
MACLEOD AND Haskins 1906 Jour. Biol. Chem., 1, 319-334.
WiNOOBADBKT 1890 Annales de Tlnstitut Pasteur, 4, 267-275.
WiNOGBADSKT AND Omeuanskt 1899 Centr. f. Bakter., 2 Abt., 6, 329,
377, and 429.
TOXINS OF BACT. DYSENTERIAE, GROUP III
TH. THJ0TTA and ODD FALSEN 8UNDT
From the BacieriologicdL Laboratory of the Nortoegian Medical Corps, Kristiania,
Norway
Received for publication, February 10, 1921
It was Shiga (1898) who first demonstrated the toxicity of
cultures of the dysentery bacillus isolated by him in 1898. Later
this toxin production has been studied by several investigators
among whom are Neisser and Shiga (1903), Conradi (1903),
Vaillard and Dopter (1903), Flexner and Sweet (1906) and Kraus
and Doerr (1905). Recently Olitsky and Kligler (1920) have
published a very interesting paper on this subject, showing
that the dysentery bacillus of group I of Thj0tta's (1919) classi-
fication (the bacillus of Shiga) produces a soluble toxin (exotoxin)
as well as an endotoxin, and that these two toxins act di£ferently
in rabbits. The former was shown to be a neurotoxin having
no intestinal action^ while the latter is an enterotoxin having no
effect on the nervous system.
In the past the dysentery bacilli of group I were considered
the only toxic forms of this bacillus, while those of the other
groups (group II of Thj0tta's classification, i.e., the types of
Flexner and Strong and the Hiss Y bacillus) were held to be atoxic.
In the following we will show that Bact. dysenteriae of group
III as well as of group I produces toxins thus showing the relation
of this group to the toxic strains of the Bact. dysenteriae.
Before going into the details of our experiments we will pre-
sent the main characters of the bacillus of group III. It is,
as in the case of other Bact. dysenteriae a Gram negative, non-
motile non-gas producing microbe, that forms acid in mannitol,
maltose, glucose, and as a rule in sucrose. It does not produce
indol and it grows in peculiar colonies having an irregular,
crenated edge. It is toxic to a milder degree for rabbits and
monkeys (Soime).
501
502
TH. TEU0TTA AND ODD FAL8EN 8UNDT
This microorganism was evidently seen by Kruse in 1907
and called by him type E (Kruse, 1907) ; but it was first regarded
as' a definite type by Sonne in 1914 (Sonne, 1915) and classed
by him. in group III. Since then it has been described in France
by d'Herelle (1916), inNorw;ay by Thj0tta (1919) and in Sweden
by Phnell (1918).
EXPERIMENTAL
As a control on our technique, and as a confirmation of the
results obtained by Olitsky and Kligler a strain of Shiga bacilli,
the first of this form of dysentery bacilli to be isolated in Norway
(by the authors) was examined.
The Shiga strain was grown in plain broth for eight days, then
filtered, and the filtrate (Berkefeld) injected intravenously in the follow-
ing rabbits with these results:
Experiment L Exotoxin
BABBIT
KUM-
WBIQBT
AMOUMT
INJBCTXD
rXBSTDAT
SBCOMD DAT
THIBD DAT
BBB
granu
ec.
1
3250
1.0
Very sick
Dead
2
4000
0.5
Sick
Lies on side,
does not
move
Dead
3
3600
0.25
WeU
Quiet
Paresis of
forelegs
Complete
paralysis
of anterior
part of
body
4
3250
0.125
Well
Well
Well
Well
5
3600
0.063
WeU
WeU
Well
WeU
Thus it is proved that the filtrate acts as a neurotoxin, pro-
ducing distinct paralysis; that a period of incubation precedes
the development of these symptoms; and that the effect is de-
pendent upon the amount of the filtrate employed. In none of
these rabbits were intestinal lesions f o\md.
The Shiga strain was grown on agar surface for twenty-four hours,
washed off in saline solution, heated for 1 hour at 60°C., and finally
TOXINS OF BACT. DYSENTEBIAE
503
warmed at 37^0. for forty-eight hours. The suspensioDS were then
filtered and injected into rabbits with the following results:
Endotoxin
RABBIT
NUMBKB
WBXGBT
AMOXTMT
XlffJBCrBD
FIBtTDAT
SaCOMD DAT
TnRDDAT
wovwem day
fframs
ee.
1
2000
l.p
Dead
2
3600
0.25-
Sick
Diarrhea
Very sick, diarrhea
Dead
3
3000
0.125-
Sick
Dead
4
2800
0.063-
Sick
Diarrhea
Dead
From these experiments it is to be noted that the prominent
symptoms were intestinal in origin. At autopsy a marked
hemorrhagic colitis was foimd, similar to that observed in
dysentery in man in the stage prior to the development of
necrosis. None of these rabbits showed nervous symptoms.
Thus the results were in accordance with the findings of
Olitsky and Kligler, and we concluded that the conditions for
obtaining a good yield of exotoxin and endotoxin were met by
our technique.
We then proceeded with the study of the Bad. dysenteriae^
group III. The reaction of the medium during the growth
varied as follows:
TABLE 1
DATS XNCUBATIOir
pH
1
7.2*
2
7.3
3
7.6
4
8.0
5
8.0
6
8.0
^Medium before inoculation pH 7.6.
We thus find an initial acid production that is followed by
a period of alkalinity. In the end the reaction is more alkaline
than at the beginning of the experiment. This confirms the
observations of Olitsky and Kligler who also foimd that the
toxin production did not begin until the alkaline period had
504 TH. THJ^TTA AND ODD FAL8EN STJNDT
set in. Following the technique of Olitsky and Kligler we collect-
ed our toxin after seven days' growth since too prolonged growth
tends to yield mixed exotoxin and endotoxin. The broth was
now filtered through a Berkefeld filter, the filtrate tested for
sterility and the toxin thus prepared was injected into rabbits and
white mice.
Experiment II. Injections into rabhiU
BABBIT NUMBBB
WBIGST
AM ouMT or Bxorozor
XN/aCTBO XBTBATBHOUBI^T
Qrama
CC,
1
2500
3.0
2
2700
2.0
3
2600
1.0
4
1250
0.5
The results were as follows :
Four hours after the injection the animals became iU. All lay quiet
without trying to move. Rabbits 1 and 2 also had quick labored
respiration and appeared to be moribund. After this immediate and
probably non-specific effect the animals returned to normal as to
appearance. If they were disturbed, however, they did not jump about
as normal rabbits do, but dragged themselves along with a distinct
weakness of the hind legs.
The weakness of the hind legs was most distinct in the second and
third day of the experiment; thereafter it gradually disappeared.
The loss of weight was as much as 500 giams (rabbit 1).
A control rabbit injected with 3 cc. of sterile broth did not show any
S3nnptoms.
Additional experiments were made but as the results were
similar the protocols are not given. The injection of filtered
broth cultures of dysentery bacilli of group III thus causes an
effect in the rabbits characterized mainly by distinct paresis
of the extremities. No diarrhea was observed and no deaths
occurred.
Endotoxins of Bad. dysenteriaey group III. The endotoxin
was prepared as follows:
Large flasks of agar^^^diameter 18 by 10.5 cm.) were incubated after
inoculation with the strains used in the experiments on exotoxin. A
TOXINS OP BACT. DTSENTERIAE
505
twenty-four hours' growth of the bacQIi was emulsified in normal saline,
and the emulsion placed in the incubator for autolysis for two days.
It was then filtered through Berkefeld candles, tested for sterility and
injected into rabbits.
Experiment III. Injections into rabbite
KABBIT
XUMBBX
WBIQBT
AMOUNT
INJBCTBD
aranu
ec.
1
760
3
2
700
2
3
800
1
4
2860
3
6
2260
2
riBSTDAT
Dead
Very ill, diar-
rhea
Slight diarrhea
Very ill, diarrhea
Normal stool
BBCOND DAT
Improved
Well
Improved
Well
FOUBTB DAT
Well, weight 660 grams
Well, weight 860 grams
Well, weight 2050 grams
Well, weight 2100 grams
Thus, the rabbits after being injected with the endotoxins
of the dysentery bacillus of group III showed intestinal disturb-
ances as indicated by the diarrhea. One animal died following
a large dose (3 cc.) after having shown a profuse blood-stained
discharge from the intestines. One animal did not show any
sign of diarrhea. In no case was there paresis, and recovery
followed promptly.
Experiments on mice
Kraus and Doerr studied the effects of the toxins of the Shiga
bacillus on hens and pigeons and found they were refractory.
Doerr likewise foimd that guinea-pigs were not affected. We
undertook the study of the effects of both the exo- and endo-
toxin on mice with the following results :
Experiment IV. Exotoxin
MOUBB XUMBBB
AMOUNT OF aXOTOXXK ZMJBCTBD
ee.
1
1.0
2
0.6
3
0.26
4
0.10
6
0.06
6
1.0*
* sterile broth.
506
TH. THJ0TTA AND ODD FAL8EN SUNDT
Four hours after the injection mice 1 to 5 had a profuse bloody
and slimy discharge from the anus, the stool hanging in drops from the
anal opening. AU the mice were sick, huddling together and showing
raised hair. Thirty-six hour after the injection the animals were all
right. Mouse 6 did not show any symptoms at all.
EzperimerU V. Endotoxin
MOUBB iniMBBB
▲UOUNT OFBNDO'
TOXIN XMJKTBO
nSRDAT
BSCOMD DAT
TKUtDDAT
1
ee.
2.0
Dead
2
1.0
Dead
3
0.5
Very sick
Sick
WeU
4
0.25
Very sick
Sick
WeU
5
0.10
Very sick
Dead
6
0.05
Sick
Sick
WeU
All the sick mice had a diarrhea of blood-stained mucus after the
injection, developing very soon (one and a half hours after injection).
At autopsy there was enterocolitis and the lumina of the intestine
contained bloodnstained mucus.
Considering the rapid development of the symptoms in mice
and the xmif ormity of the latter in both experiments it is probable
that the symptoms were non-specific, at least where the exotoxin
is concerned. As to the endotoxin, this certainly made the
mice very sick and even killed them, the toxicity of the filtered
broth thus being certain. However whether this toxic action
was only due to the non-specific bacterial protein toxicity or
indicated the specific action of a dysentery toxin we cannot
state with certainty.
Antitoocins
Our next step was to study the production of antitoxins in the
blood of immunized animals and to determine whether these
antitoxins were capable of neutralizing the action of both the
exotoxin and the endotoxin. For this purpose strong full-grown
rabbits were used. The first rabbit receiving exotoxin died
from a fulminating intoxication after three injections. The next
aninaal bore the injections well and was given 10 doses of 1 cc.
TOXINS OF BACT. DYSENTERIAE
507
each before the senim was drawn. An endotoxin animal also
received 10 injections of 1 cc. each before the serum was used:
and after these injections both these animals were apparently
immune against the corresponding toxin.
Owing to a shortage of animals we have made only one experi-
ment with rabbits. We chose to try endotoxin as this toxin
showed more distinct symptoms of poisoning than the exotoxin.
AJmXK'
DOTOXIX
KMXTUn
ce,
3
3
ee,
1.0
0.1
m
Well, no diarrhea, loes of weight in 2 days, 60 grams.
Slight diarrhea, loes of weight in 2 days, 200 grams.
■MDOTOXnt
▲IfTIBXO-
TOXIN
■asuMS
ce.
3
3
3
3
ee.
1.0
0.5
0.1
0
1
Very sick, diarrhea
Very sick, diarrhea.
Very sick, diarrhea, died in 20 hours after injection.
Very sick, diarrhea, lived
In this experiment the sick animals and the one death occurred
in the tests made with heterologous toxin and antitoxin, while
the animals that were injected with the mixture of homologous
toxin and antitoxin were fairly well.
We are quite aware that our doses were large and our animals
few. But we cannot free ourselves of the opinion that there
was a distinct antitoxic action exercised by the sera from the
animals immunized against the homologous toxins. The titra-
tion of this action in exact doses was hardly possible because
of the mild action.
We now turned our attention to the effect of neutralizing
sera on mice, which, as noted previously, acted in a non-specific
manner to the action of exotoxin, and possibly in a specific manner
to that of the endotoxin.
508
TH. THJ^TTA Ain> ODD FAL8EN SUNDT
SKDOTOXIN
AirriBin>o-
TOXIN
BBSUI.TB
ee.
2
2
2
ee.
0.5
0.1
0.01
All animalB well
All animals well
All animals well
■NDOTOXIN
AMTZBXO-
TOXIN
BBSULTB
oe.
2
2
ee.
0.5
0.1
Sick with diarrhea, lived
Sick with diarrhea, died within 24 hours
BKDOTOXIN
NORMAL
BBBCTM
BKSVUIB
ee.
2
ee.
0.5
Sick, diarrhea, lived
■ZOTOXXN
ANTIBXO'
TOXIN
'BB8UIT8
ee.
2
2
2
2
ee.
1.0
0.5
0.1
0.05
Slight diarrhea, lived
Well
Died in 24 hours
Well
BXOTOXIN
ANTZBNDO-
TOXIN
BBBXTUm
ee.
2
2
2
2
2
ee.
1.0
0.5
0.1
0.05
0.005
Died in 24 hours
Sick without diarrhea
Sick without diarrhea
Sick without diarrhea
Died in 24 hours
The experiment seems to show a distinct protective action
of the antiendotoxin serum against its homologous toxin, while
the control tests with endotoxin and antiexotoxin serum did
not show protection. It seems therefore justifiable to consid^
the toxic effect of the extract of the dysentery bacilli (the "endo-
toxin'') as a specific action due to the endotoxins of the dysen-
tery bacillus rather than to a non-specific protein toxicity.
In the tests with exotoxin we did not find any distinct neu-
tralization of the toxic effect of the broth injected. This fact
might be due to the short period of immunization of our serum
TOXINS OF BACT. DYSENTEBIAE 509
yielding animals. In comparison however with the non-specific
appearance of the symptoms of the exotoxin injection we find
that this lack of neutralizing effect of the antiexotoxin sermn
makes it still more probable that the reaction of the mice after
injection of exotoxin must be characterized as a non-specific
reaction.
CONCLUSIONS
1. Bad. dysenteriae of group III produces both exotoxin an4
endotoxin.
2. The endotoxin is the most marked in effect and produces
intestinal symptoms in rabbits and mice, while the exotoxin of
this group is milder in action, producing pareses in rabbits,
while mice react non-specifically to it.
3. The repeated injections of these toxins over a relatively
short period of time render rabbits immune. The sera of these
animals show a weak protective action against the homologous
toxins.
REFERENCES
CoNBADi, H. 1903 Deut. med. Woch., 89, 26.
D'Hebbllb, H. 1916 Ann de Tlnst. Pasteur, 80, 145
FusxNEB, S., ANB SwBET, J. E. 1906 Jour. Exp. Med., 8, 514.
Kbaus, R., and Dobbb, R. 1905 Weiner Klin. Woch., 18, 514.
Kbuss, 1907 Deut. Med. Woch., 3S, Nos. 8 and 9.
NxiBSXB M., AND Shiga, K. 1903 Deut. med. Woch., 89, 61.
0HNSLL, H. 1918 Kliniska och bakteriologiska bidrag till k&nnedomen om
dysenterien i Sverige, Stockholm.
Olitbkt, Pbteb K., and Kliglbb, I. J. 1920 Jour. Exp. Med., 81, 19.
Shiga, K. 1898 Centr. f. Bakt., 88, 599.
SoNNB, C. 1915 Centralbl. f. Bakt., 76, 408.
THJ0TTA, Th. 1919 Jour. Bact., 4, 355.
Vaillabd, L., and Dopteb, C. 1903 Ann. de Tlnst. Pasteur, 17, 486.
SALT EFFECTS IN BACTERIAL GROWTH^
I. PRELIMINARY PAPER
' GEORGE E. HOLM and JAMES M. SHERMAN
Pram the Research Laboraioriee of the Dairy Dwision, United States Department
of Agriculture, Washington, D. C.
Received for publication February 28, 1921
The Hofmeister series shows the effects of ions of neutral
salts upon the coagulation of colloids and upon the swelling and
other physical properties of proteins. Our knowledge of these
ion effects in solution has been greatly extended by Freundlich
and his students. They noted that the ions could be arranged
in a definite order with respect to their effects upon compressi-
bility, surface tension, solubility, viscosity, absorption, ratio of
reaction, etc. Freundlich seems to favor the hydration theory
of salts as an explanation of this neutral salt action, and since
the properties affected are so closely related and boimd up with
one another, and the ions so consistent in their order of effect,
he calls these effects "lyotropic" effects. The lyotropic expla-
nation does not lay claim to being a full explanation of neutral
salt action, but it does lay claim to correctness in that it system-
atically treats complicated phenomena.
In most cases the influence of the anion far outweighs that of
the cation and the order of anion effects usually reads as follows,
F>S04>P04>Cl>NO,>Br>I>CNS; while the order of ar-
rangement for the cation is usually Ca>Sr>Mg>Cs>Rb>
K>Na>Li. The same sequence is obtained in the widely
differing changes mentioned above and does not seem to f oUow
any recognizable order with respect to valency, atomic weight,
etc. Certain reagents may promote or hinder the salt effects
as compared with those in pure solution. In some cases the
^ Published with the permiasion of the Secretary of Agriculture.
Ml
JOUBKAL OV BAOraBXaLOQT. TOI*. TZ, MO. 6
512 GEORGE E. HOLM AND JAMES M. SHERMAN
order of effects may be reversed when changes take place in
acid or in alkaline solutions, but the sequence usually remains
the same.
The lyotropic effects of salts upon compressibihty, surface
tension, solubiUty, etc., of organic and inorganic substances in
solution is not great in most cases. It is in the field of colloid
chemistry that these effects attain a magnitude of great signifi-
cance. A review of the literature covering this field is out of
the question here, but a few citations from the biochemical
field will serve to show the reasons for extending the work to
the field of bacteriology.
In view of the recent and extensive investigations of Loeb
(1918-1921) upon the physical and chemical properties of pro-
teins it will probably be necessary to modify certsdn conceptions
now held concerning the relative magnitude of various ionic
effects in protein solutions. As to whether the Hofmeister
series of ions will be shown to be entirely a delusion, as is believed
by Loeb, we do not care to express an opinion, and it is not the
purpose of the present paper to take sides on that controversial
question.
Whatever may be the status of ion effects in protein chemistry,
specific ionic effects in biological phenomena have been well
established by the work of Loeb and many others. It is our
purpose to study systematically salt effects, especially the quali-
tative and quantitative relationships of radicals (anions and
cations), as related to bacterial growth, and to correlate these
findings with other effects which have been noted in pure chem-
istry as well as in biology.
Closely related to the phenomena of hydration and coagulation
is that of permeability and diffusion. On the basis of the view
of Bechhold and Ziegler (1919) that membranes do not act like
sieves, but as though they were a network of arranged ions, it
is easy to conceive of enormous salt effects upon permeability,
both by influence upon ions which are to diffuse and by effects
upon ions formmg the membrane network.
Bacteria perhaps represent matter in a state as near the state
of colloids and also as near the state of living protoplasm as
SALT EFFECTO IN BACTEBIAL GROWTH 513
any organism does. The effects of salts should therefore not
only be very marked but might reach magnitudes that ought to
be taken into accoimt in the culture of bacteria.
Brooks (1919) found that NaCl and KCl in concentrations of
0.15 to 0.20M increased the rate of respiration of B. avbtilis,
while in higher concentrations they decreased the rate. CaCU
increased the rate in a concentration of 0.05M and decreased
the rate in higher concentrations. Dealing with the respiration
of Aspergillus niger, Gustafson (1919) likewise found a stimu-
lation by NaCl in concentrations of 0.25 to 0.5M and by 0.5M
CaClj.
The work of Winslow and Falk (1919) shows that NaCl and
CaCl2 both increase the mortality of Bact. coli in water. In
the case of NaCl 5 isotonic was distinctly lethal, while in the
case of CaCU 0.1 isotonic was injurious.
Greaves (1916) foimd the toxicity of anions as measured by
ammonification in soils to be in the following order: Cl> NOs>
S04> COs. He also noted that the toxicity of some salts in-
creases more rapidly with increased concentration than does
that of others. This action he ascribes to the physiological
factor of the organism rather than to the osmotic pressure or
salt action of the solution.
The influence of alkaline salts upon phagocytosis was found
by Radsma (1920) to depend mainly upon the anions but also
somewhat upon the cations. Radsma explains the effect as
surface action and considers it an indication of colloidal chemical
structure of protein substances at the surface.
Mathews (1906) pointed out that the action of salts upon the
protoplasmic system is due chiefly to the ions of the salts and he
considers the physiological action dependent upon the available
potential energy.
Whether or not the salt action upon bacteria is due to the
available potential energy of the ions we shall not attempt to
decide. We merely wish to point out in this paper that salts
do affect bacterial growth much in the same manner as they
affect chemical reactions, coagulation, permeability, etc., that
514 OEOROiS S. HOLM AND JAMBS M. 8HEBMAN
this effect is modified by the hydrogen ion concentration of the
medium, and that such effects are probably great enough to be
given consideration in bacterial culture.
EXPERIMENTAL
The organism used was Bact. coli, and the basic medium chosen
was a 1 per cent pepton solution to which was added the crystal-
line salts in amounts necessary to give the desired concentrations. '
The media were autoclaved and filtered in case of the formation
of a slight precipitate. At this point the pH was adjusted if
necessary with HCl or NaOH, and the media tubed and steril-
ized. These tubes containing 10 cc. were in each case inoculated
with a loopful of a yoimg culture and incubated at 37°C.
There was some question as what should constitute a measure
of bacterial growth and what factor would be constant enough
for comparative purposes. The reduction of methylene blue
was first tried. In this case a layer of paraffin oil was used to
prevent oxidation by the air. Although it worked quite satis-
factorily, it was found that reoxidation occurred in the cases
where bacterial action was slow, and thus, instead of giving a
sharp end point, really increased the time for reduction. The
rapidly growing cultures gave a sharp end point. It was noticed,
however, that a slight turbidity was apparent in most cases
before reduction could be detected. It was decided, therefore,
to use the first sign of turbidity as an indication of the rapidity
of bacterial growth.
A few trial experiments indicated that the two methods of
detecting growth checked very well, except for the fact that
turbidity was first detected and proved a sharper measure than
reduction. The first sign of turbidity when the tubes were
held against a strong artificial light was therefore used to measure
rapidity of growth. This method was further verified by grow-
ing the same organism in a medium of 1 per cent pepton con-
taining 1 per cent lactose and adjusted to a pH of 7.0. The
production of acidity paralleled the results obtained by reduction
and visible turbidity.
SALT EFFECTS IN BACTERIAL QBOWTH
515
Inasmuch as the anionic effects seem to be predominant in
chemical reactions it was decided to try the effects of salts having
a common cation (sodimn). The salt concentration chosen to
be used was 0.20 molar, which was low enough to give the ionic
effects and not too pronounced osmotic effects of the salts. To
eliminate as nearly as possible H-ion effects the pH was adjusted
to 7.0, colorimetrically, before final sterilization.
TABLE 1
Showing th4 effect of varioiu sodium aalie upon the rate of growth of Bact, coli
uaoam
pH
TIMS RXQUIRBD TO
•BOW TUBBIDITT
1 Der cent Depton
7.2
7.3
7.3
7.3
7.0
7.3
7.0
7.0
7.0
7.3
7.4
koUTM
41
1 Der cent DCDton 0.20 M NaCl
•**
31
1 Der cent DCDton 0.20 M Nal
"4
31
1 per cent pepton 0.20 M NaNOi
«#2
31
1 per cent pepton 0.20 M Na^O«
4
1 per cent pepton* 0.20 M Na H POi
41
41
1 per cent peptont 0.20 M Na lactate
1 per cent pepton 0.20 M Na oxalate
^1
91
1 per cent pepton 0.20 M Na acetate
•1
101
1 per cent pepton 0.20 M Na citrate
1 per cent pepton 0.20 M Na fluoride
48
* Mono-and di-eodium phosphate were mixed in proper proportions to give
a pH of i^pproximately 7.0.
t The sodium lactate used was prepared by adding NaOH to lactic acid until
a pH of 7.0 was reached.
Table 1 shows the effects pf various sodimn salts upon the
growth of Bact. coli. The table indicates that the CI, I, NOs,
SO4, PO4, and lactate ions accelerate growth of Bact. coli, while
the other ions tried mhibit to a greater or less extent. Usmg
the CI, I, SO4, and lactate ions in the same concentrations, the
series was repeated with the following results:
Time
Mtdum koura
1 per cent pepton 41
1 per cent pepton 0.20 M NaCl 31
1 per cent pepton 0.20 M Nal 31
1 per cent pepton 0.20 M Na lactate 31
1 per cent pepton 0.20 M NaiSOi 41
516
GEORGE E. HOLM AND JAMES M. SHERMAN
Table 1 indicates that there is a marked effect of salts upon
the growth of Bact. coli, and it would seem that it is largely due
to the anion.
To find out to what extent the cation affects such growth the
effect of the following salts were tried: KCl, NaCl, NH4CI,
MgCl,, CaClj, and FeCl,. Table 2 gives the effects of 0.20
molar concentrations of these salts upon growth. Table 2
seems to indicate that there is little difference between the effects
of the Na, K, and NH4 ions. Since in the case of MgCU we have
twice the concentration of CI ions which we have in the former,
a true comparison cannot be made if the anionic effects pre-
dominate. To make our experiments comparable we compared
growth in a 0.20 molar NaCl pepton medium with growth in
TABLE 2
Shoufing the effect of various cations upon the rate of growth of Bact, ccii
MKDIUII
1 per cent
1 per cent
1 per cent
1 per cent
1 per cent
1 per cent
1 per cent
pepton
pepton 0.20 M NaCl. .
pepton 0.20 M KCl. . .
pepton 0.20 M NH«C1
pepton 0.20 M MgCls.
pepton 0.20 M CaCli.
pepton 0.20 M FeClt. .
TOOL mBQDtUD TO
SHOW TCBBmiTT
kovr§
5
3i
3f
3i
8
120
No growth
0.10 molar MgCU pepton medium. The effects of 0.40 molar
NaCl and 0.20 molar MgCU were also tried.
The resxilts are shown in table 3. MgCU and NaCl, therefore,
in concentrations where the number of CI ions is the same, are
comparable in effect. That there is a cation effect in greater
concentrations, however, is shown by the fact that the time for
0.20 molar MgCU is 12 hours, while that for 0.40 molar NaCl
is but 4f. Doubling the NaCl concentration changes the time
rate very little, while doubling the MgCU concentration more
than triples the time. This is strong evidence that there is a
cation effect, though it may not be so marked as the anion
effects. CaCli has a much stronger inhibiting effect while
FeCU entirely inhibited growth in the concentration used.
SALT EFFECTS IN BACTERIAL OROWTH
517
Our results so far have been obtained upon media adjusted
to a pH of approximately 7.0. Since we know that the H-ion
concentration materially affects growth of bacteria, it is of both
interest and value to know to what extent the salts modify the
time element at pH values on either side of neutrality. Table 4
shows these effects with the salts given and at the H-ion con-
centrations stated. The results indicate that the different salts
TABLE 3
Showing the effects of various concentrations of NaCl and of MgClt upon the rate
of growth of Bact. coli
MEDIUM
pH
TIMS BEQUIBBD TO
BHOW TUXBIDITT
1 per cent pepton 0.20 M NaCl
7.0
7.0
7.0
7.0
Amira
3}
1 per cent pepton 0.40 M NaCl
"4
4}
1 per cent pepton 0.10 M MirClt
31
1 per cent pepton 0.20 M MflcCU
"4
12
TABLE 4
Showing the effects of various salts upon the growth of Bact, coli at different H-ion
concentrations
MBOIVM
'1 per cent pepton
1 per cent pepton 0.20 M NaCl
1 per cent pepton 0.20 M NaiS04. . . .
1 per cent pepton 0.20 M Na citrate
TZMB 0* ViaiBLB OBOWTH AT
pH
YALuas or
ft.2
«.2
7.t
8.2
9.2
hour»
luxtn
iotir*
k0VT9
hour*
m
6i
«
8
32
»
4i
3J
3
14
6J
4i
4i
3J
20
8i
7J
22
have marked changes of effect with changes in pH. In general
we may say that NaCl and Na2S04 widen the optimum range of
growth, while Na citrate narrows this pH range.
DISCUSSION
The data presented show in a general way some correlation
between the so-called lyotropic series and the order of effect
upon the growth of BacL coli. There are, however, ions which
518 GEOBGB £. HOLM AND JAMES M. SHERMAN
are exceptions and which, in concentrations thus far tried, have
proved highly retarding in their action. These ions are the
sulphocyanate and fluoride. Whether in lower concentrations
they might not prove but slightly retarding or even beneficial
to growth remains to be ascertained. The position of the SO4
radical with regard to effect upon bacterial growth is also some-
what at variance with its usual position in the lyotropic series.
Instead of being foimd opposite the iodine end of the series it
is found next to the CI and I radicals.
While these are deviations from the usual order, it is not
surprising since in many of the phenomena in biochemistry the
lyotropic order does not strictly compare with the usual order
as determined by effects upon surface tension, viscosity, etc.,
especially at different concentrations and temperatures. We
must also remember that here we are dealing with an added
factor which is not present with proteins in solution or with
colloids in general; that is, the life of an organism. Since this
is our measure of effects it must be taken into account. We
do not know what properties affect viability most, and conse-
quently we have no means of knowing what mechanism causes
retarding and inhibitory effects. There seems to be, as might
be expected, an order of specificity which must be taken into
accoimt.
The general order of the lyotropic series, however, holds at
pH 7.0 CI and I are foimd at one end of the series aiding or*
accelerating action, while the citrate, acetate, and oxalate at
the other end retard growth.
Considering the effect of cations, we have a close analogy
between action here and action of salts in the animal body.
As might be expected, there is little difference between the Na,
K, and NH4 ions. With Mg the action begins to manifest
itself, although it is greatly modified by the anion effect. The
calcimn ion produces its characteristic strong effect.
It is in media of different H-ion concentrations that these
effects become significant. In the region of optimum growth the
influences are not exceedingly marked, but as we near the H-ion
concentrations which mark the limits for growth of Bad. coU
SALT EFFECTS IN BACTERIAL GROWTH 519
the differences in the rate of growth are greatly increased. In
other words the H-ion range for optimum growth is widened or
narrowed as shown in the table given.
This factor becomes of practical value in adjusting media
for optimum bacterial growth. The figures show that certain
ions are of value in pepton media for accelerating the growth
of Bad. coli and also for widening the range for optimum growth,
while certain other ions narrow the H-ion range and decrease
the rate of growth. This would perhaps explain the findings
of Cohen and Clark (1919) that culture media adjusted with
HOI had a higher limit of growth on the acid side than media
adjusted with acetic acid.
SUMMARY.
It has been shown that the growth of Bad. coli in 1 per cent
pepton medium is accelerated or retarded by different salts in
low molecular concentrations.
The salt effects at various H-ion concentrations vary greatly.
Those salts which accelerate growth seem to widen the H-ion
range for optimum growth, while those which retard growth
seem to narrow the limits for optimum activity.
Cations and anions are both effective.
REFERENCES
■
Becbhold, H., and Zieqlkr, J. 1919 In Colloids in biology and medicinOi
by H. Bechhold and J. G. M. Bullowa, p. 55.
Brooks, M. M. 1919 Jour. Gen Physiol., 2, 5.
Cohen, B., and Clark, W. M. 1919 Jour. Bact., 4, 409.
Greaves, J. E. 1916 Soil Science, 2, 443.
GusTAFSON, F. G. 1919 Jour. Gen. Physiol., 2, 17.
LoEB, J. 191&-1921 Jour. Gen. Physiol., 1918-19, 1, 39, 237, 363, 483, 559; 191^
20, 2, 87, 273; 1920-21, 3, 85, 247, 391.
Mathews, A. P. 1906 Jour. Infect. Dis., 3, 572.
WiNSLow, C.-E. A., AND Falk, I. S. 1919 Abs. Bact., 3, 5.
SUGGESTIONS CONCERNING A RATIONAL BASIS FOR
THE CLASSIFICATION OF THE ANAEROBIC
BACTERIA!
STUDIES IN PATHOGENIC ANAEROBES. IV
I. PRELIMINARY PAPER
HILDA HEMPL HELLER
From the George Williama Hooper Foundation for Medical Researfih, University
of California Medical School, San Francisco
Received for publication March 1, 1921 -
During the past three or four years I have made a study of
a carefully controlled series of certain groups of anaerobic strains
secured from pathological material. Attention was directed
almost entirely to such strains as were found to be capable of
penetrating living guinea-pig muscle in doses of 1 cc. or less
of yoimg ground beef-heart culture. B. WeUhii was not con-
sidered, and this organism is not included in the following list.
Though I was forced for want of time to neglect non-pathogenic
forms, such organisms are so frequently encoimtered in a study
of pathological material that one who has collected anaerobes
of one group must necessarily observe those of other sorts and
learn something of their ways. The pathogenic tissue-invading
strains included in my collection are 80 in number: 23 from
human wound infections, 32 from cases of so-called ''blackleg"
of cattle, 10 from cases of braxy and of blackleg of sheep, and
15 from other animals. The collection includes 30 odd strains
of tetanus and other proteoljrtic organisms of various sorts.
^ This work and that described in the following papers was commenced during
the author's tenure of the Alice Freeman Palmer Fellowship of Wellesley College.
521
522 HILDA HEMPL HELLEB
All strains were carefully isolated and the cultures were con-
tinually observed in order to detect contaminations.^
The samples collected, though they do not exhaust the patho-
logical material from anaerobic infections, are very widely repre-
sentative, and the collection of much more material and the
isolation from it of many more pathogenic strains would be an
exceedingly arduous task. It must also be borne in mind that
in greatly increasing the number of strains under observation
one must necessarily relax the vigilance with which he criticises
the purity of those strains which are studied. The examination
of any considerable number of anaerobes is a comparatively
new task, and any proposal for classification which is made
at the present period is bound to be a temporary one. The
time is imquestionably not ripe for an elaborate study of several
himdred strains of any particular type of anaerobe because the
material for such a study has never been collected, and such a
collection would represent several years' work and a consider-
able outlay for experimental animals. But the cultures that I
have been able to isolate during the past few years have furnished
so much material for investigation, and the information gsuned
from them has so radically altered my attitude toward the
anaerobic group, that I feel that the time has arrived to state
my results, to organize them as consistently as may be, and to
propose a system for their classification. In other words I feel
that the status of the classification of the anaerobes is today so
chaotic and unsatisfactory that a pioneer effort at a logical
grouping according to our present knowledge is very much
needed. If we consider the fact that the investigated material,
when compared with the vast amount of iminvestigated material)
is exceedingly scanty, we shall not expect such a classification
to be final. We have today, however, a fairly definite con-
ception of the pathogenic anaerobes, and by analyzing the
* An account of the affinities of the animal strains studied will be found in
part in The Journal of Infectious Diseases for November, 1020, Vol. 27, and in
full in the Collected Reprints of the Hooper Foundation for 1921, Vol. VI, und«r
the title "Etiology of Acute Gangrenous Infections of Animals." This paper
contains a description of the methods employed in the isolation of my cultures.
CLASSIFICATION OF ANAEROBIC BACTERIA 523
groups thus studied we shall be enabled so to orient our classi-
fication of the whole anaerobic group that some conception of
its size and general relationships will be presented for the use of
future investigators.
The uncertainties prevailing in the classification of the an-
aerobes, apparent to anyone who has tried to identify an isolated
anaerobic stram, become more glariAg as one proceeds to study
several strains that were handed to him imder the same name,
but which display great differences in their behavior. Later,
on continuous study of anaerobes of various types, and of the
literature of anaerobic infections, the worker comes to the reali-
zation that identifications by means of descriptions found in the
existing literature can at best be only tentative and approxi-
mate, and that the majority of those type strains on which were
based the descriptions to which we are compelled to refer for
priority are now lost or badly contaminated; Thus a large
number of the older descriptions are potentially invalidated,
or orphaned, so to speak, and cannot, today, be used for any
definite systematic purpose, and the names proposed in those
descriptions are now nomina nuda. This situation must be
deliberately faced. What we need is an elastic, adaptable system
of classification in which the old descriptions can find, a place
as well as the new: a system consistent, also, with the Rules of
Botanical Nomenclature, whose adoption has been proposed by
the Committee of the Society of American Bacteriologists.
FORBiER CLASSIFICATIONS
It is necessary to consider what have been the methods of
classifying our group that have been proposed by other workers.
Zopf defined the genus Bacillus as including: "Cocci and rods
with spores" and the genus Clostridium as: "like Bacillus but
spores in spindle-shaped elements."
Kruse (1896, pp. 67 and 185) included in his family of Bacil-
hiceae three groups which comprise the anaerobes. They are:
6. The malignant oedema group: large spore-bearing anaerobic
bacilli. Saproph3rtic or parasitic. Colonies on agar usually stellate.
JOXnUCAL OV BACTBBXOLOaT, YOL. TI, HO. 0
524 HILDA HEMPL HELLER
No change in form of mother cell on spore formation. Less easily
stained by Gram method than preceding group (anthrax group).
Usually liquefy gelatin and produce foul odors.
7. The symptomatic anthrax and but3Tic acid group. Large baciDi
that swell to form Clostridia on sporulation, saprophytic and parasitic,
mostly anaerobes.
8. Tetanus group. Fairly large bacilli with drumstick (Knopfchen)
spores. Mostly anaerobic parasites and saprophytes.
Migula (1900) included in his family Bacteriaceae the peri-
trichiaUy flagellate rods in one enormous genus, Bacillus; the
non-flagellate rods in another, Bacterium.
Fischer (1903) in his second classification divided the Bacd-
laceae into: Sporulating and non-sporulating rods, sporangia
unchanged in shape, BadUieae; and spore-bearing rods modified
in shape: spindle-shaped, Clostridieae, and drumstick shi^,
Plectridieae.
Lehmann and Neumann (1904) divide the Bacteriaceae into
the genera: '* Bacterium, without endogenous spores, rods usually
imder 0.8 to 1/x in diameter," and "BadUus, with endogenous
spores, rods often more than I/jl in diameter."
OrlarJensen (1909) in his comprehensive reorganization of
systematic bacteriology according to the chemical behavior of
the organisms, proposed for the higher bacteria the order Peri-
trichinae, to include rods and spherical forms which show a
marked tendency to split carbohydrates and amino-acids. In
this order he proposed four f amiUes, two aerobic and two an-
aerobic, two producing acid and two producing alkali. The
anaerobic families he called Bviyribacteriaceae and Putnbac-
teriaceae. He would place with these, I presume, the anaerobic
cocci, and spore-formation is evidently not a requisite criterion
for admission to the anaerobic groups. In the Butyribacteriaceae
he proposed three genera: ButyribaciUv^ (to include B. Welchii
and B. Chauvoei), Pectohadllua, and CeUuhbaciUus. In the
Pviribacteriaceae he proposed the genera PviribadUus and Boivlo-
bacillus, the latter to include B. botulinv^ and B. tetani on account
of their toxin production.
CLASSIFICATION OF ANAEROBIC BACTERIA 525
The Committee of the Society of American Bacteriologists
(1920, classification first formulated in 1917) places in the family
(no. VII) BaciUaceaSy spomlating rods, two divisions which are
ranked as genera. These are: 1. The genus ^^ Bacillus Cohn
1872 Aerobic forms. Mostly saprophytes. Liquefy gelatin.
Often occur in long threads and form rhizoid colonies. Form of
rod usually not greatly changed at sporulation. The type
species is BadUus svhtiKs Cohn:" and genus 2: ''Clostridium
Prazmowski 1880 Anaerobes or micro-aerophiles. Often parar
sitic. Rods frequently enlarged at sporulation, producing
Clostridium or plectridium forms. The type species is Clostri-
drum buiyricum Prazmowski."
Breed, Conn and Baker (1908) commented at length on the
major divisions proposed by the Committee: "This family, for
the spore forming rods, has very good justification. The two
genera. Bacillus and Clostridium can probably be separated, but
whether on the basis of relation to oxygen or of shape of the
sporangium, the future must decide. Although relation to
oxygen is a very important physiological distinction, it must
be admitted that the selection of a physiological basis for the
separation of these two genera is rather unsatisfactory. It
places some of the polar-spored organisms in one genus, some
in another, and raises the question where to place facultative
anaerobes like B. mycoides and B. cereusJ^ These authors
proposed a family (5) : ''BaciUaceae, rods producing endospores,
usually Gram-positive. Flagella, when present, peritrichous.
Primarily saprophytes secreting proteolytic enzsrmes. A few
parasites." This family would include the majority of the
anaerobes and many aerobes.
Buchanan (1918, a and b) reclassified the bacteria, using
physiological characters far less than did the Committee. His
classification of the non-acid-fast members of the family JBoc-
teriaceae, sporogenous rods, is as follows: Tribe 1. Bacilleae,
endosporogenous rods, with four genera: 1. Bacillus j Aerobic
rods, usually Gram-positive, as a rule liquefying gelatin, spores
usually not distorting rods when formed. 2 and 3. Anaerobic
or micro-aeropliilic usually: 2. Plectridium, spores produced at
526 HILDA HEMFL HELLEB
extreme tip of cells, forming typical drumsticks. 3. Clostridium,
spores not produced at extreme tip of cells, at least not forming
drumsticks. Cells usually somewhat swollen when spores are
formed. 4. MetabacieTium, with usually a number of spores
within a swollen cell. Tribe 2. Bacteriaceae, not producing
endospores.
Rahn (1920) defines the anaerobes as sporulating rods that
store up logen (granulose) with or without glycogen. He
believes that further research would show the possibility of
changing any spore-forming anaerobe into another.
THE CHARACTERS USED FOR CLASSIFICATION
Let us consider the value in classification of the characters
whose use has been proposed in the above arrangements.
Morphology of the vegetative cell. Most of the authors define
the Badllaceae as rods. Exceptions to this rule are the arrange-
ments of Zopf (1885) who believed in the transformation of
bacterial species, and of Jensen (1909), who used physiological
characters for his classification. Both Zopf and Jensen state
that spherical forms may be included in such a family. Appar-
ently the unity of origin of the cocci has never been settled by
systematists. Winslow and Winslow say (1908): "Yet a con-
sideration of the properties of the members of the group makes
it clear that they are mutually interrelated and all sharply
separated from the rod-shaped bacteria, except perhaps at one
end of the series which they form." Breed, Conn, and Baker
do not consider the question of the unity of the origin of all
spherical bacteria as settled. The series of strains which Winslow
and Winslow used for their study did not, I believe, include any
strict anaerobes. Many cocci are facultatively anaerobic.
Strict anaerobes of this group are only occasionally met with,
but it does not follow that their occurrence is very rare, because
the usual technique for the isolation of anaerobes involves some
heating process that eliminates the non-spbrulating organisms.
Anaerobic cocci have been described by a number of authors.
Ozaki reviewed the subject (1915). There are, in his list, four
CLASSIFICATION OF ANAEROBIC BACTERIA 527
diplococci, three micrococci, and four staphylococci, one of these
latter appearing at times as a streptococcus or as a micrococcus.
Anaerobic streptococci are, according to Hiissy and Bondy,
normally human saprophytes which may become parasitic.
They are commonly found in cases of puerperal endometritis,
according to these authors and according to Schottmiiller.
Adamson isolated anaerobic diplococci from eighteen out of
fifty-one wounds. Sternberg has described an anaerobic strepto-
coccus. Anaerobic cocci have been found in the blood of scarlet-
fever patients by Dick and Henry and in that of measles patients
by Ttunnicliff. Beijerinck (1906) finds a sarcina in soil that is
a fermenting anaerobe. Winslow and Winslow did not find
the arrangement of the cells of the cocci a good basis for classi-
fication. About half the anaerobic cocci produce gas in sugar
media. Probably nothing can be decided as to the real afiinities
of these anaerobic cocci until the chemical behavior of some of
them has been studied by one worker and has been compared
with that of the anaerobic rods. A morphological basis, when
one considers the varied types of anaerobic cocci, would cer-
tainly lead one to conclude that anaerobiosis had been inde-
pendently acquired by certain strains of the various tjrpes.
Here, as in many cases, morphological and chemical criteria
flatly contradict each other. But form of cell (sphere, rod, or
spiral) is certainly to be recognized as a much more fundamental
character than is the arrangement of cells. Nevertheless, Alm-
quist found that bacilli may grow as spheres at low temperatures.
Yet it would seem that the anaerobic cocci do resemble other
cocci in their chemical behavior more than they do the anaerobic
rods (see Adamson, 1918-19, p. 394). So for the present it is
advisable to exclude them from an anaerobic group which con-
tains rods. The chemical study of the anaerobic cocci should
be more extensive before they can be placed anywhere.
Motility. The possession of flagella was used as a primary
character for classification by Migula, spore-formation being
given a secondary place. Chester followed Migula in crediting
importance to this character; but other workers have not done
so. The Committee (1920, p. 516) state: 'The prominent place
528 HILDA HEMPL HELLEB
given to motility seems to us to constitute a peculiar infelicity
in these schemes." And Winslow and Winslow (1908, p. 52)
do not find motility correlated with other characters in the
group of the Coccaceae. It would seem that for our purposes
the character of motility was entirely unsuited for the making
of major divisions. Thus organisms in general so similar as
B. Welchii and B. Chauvoei were placed by Migula's system in
entirely different groups because one was flagellate and the
other was not. And aerobes of many sorts and proteolytic
anaerobes dwell in his work peacefully side by side with B.
Chauvoei in the enormous and unwieldy genus BadUus; while
JB. Welchii on accoimt of its nudity is relegated to the genus
Bacterium along with Bacterium tuberculosis and other strangers.
Spore formation has been turned to by many classifiers as
an important character for the subdivisioii of the rod-like forms.
Zopf, Kruse, Fischer, Lehmann and Neumann, the Committee,
and Breed, Conn, and Baker have used it as a basis for making
their primary division. It is probable that this is a character
of far more value than is motility. It is, however, true that,
though there are many similarities between the sporulating
rods, we have no proof that they are more closely related to
each other than they are to some of the non-sporulating rods,
or that the formation of spores originated with any one type.
Should we accept such a h3rpothesis, we should still be unable
to show that certain sporulating rods had not lost their power
of spore-formation. This power is certainly an advantage to a
species, and on that accoimt anaerobic forms losing it are not so
likely to persist as are others. But that does not mean that
such a phenomenon may not occur.
Kruse strenuously protests (1896, p. 81) the use of spore-
formation as a primary character. Moreover the adoption of
spore-formation as a character for the subdivision of the rods
would make us exclude from the anaerobic group such organisms
as B. egens, B. necrophoruSy Bacillus D erf Adamson, B. fragUis
of Veillon and Zuber, and probably a goodly number of imde-
scribed organisms which in their behavior closely resemble the
sporulating anaerobes. I find that B, egens and another Gram-
CLASSIFICATION OF ANAEROBIC BACTERIA 529
positive pathogen are so similar in many respects to B. Welchii
that they might easily be identified as one species by many
workers, and it is evident that only an artificial classification
would separate them, yet B. egens and the other pathogens have
not been shown to produce spores. Asporogenous anaerobic
rods have not been frequently reported, but when one remembers
that the preliminary step in isolating anaerobes is usually a
heating process, it will be clear that the proportion of anaerobes
that do not sporulate may be considerably greater than one
would estimate on the basis of published descriptions. The
soil mixtures from which Weinberg's organisms, B. egens of
Stoddard, and my above-mentioned pathogen were isolated had
all been subjected to a physiological weeding out in human tissue
before they were inoculated into media, and a colony method
without heating was thus practicable for isolation purposes.
The matter of a primary division of the rod-shaped bacteria
then simmers down to a question of whether an anaerobic habit
or a spore-forming habit is the more fundamental one. It is
perfectly evident that certain asporogenous anaerobes have
closer physiological affinities with certain sporulating anaerobes
than the latter have with the sporulating aerobes or even with
most other anaerobes. We may have in the power of sporulation
such a phenomenon as that noted among the insects: there are
primitively wingless insects, the Thysanura, and there are vari-
ous types of insects, such as the Siphonaptera, and the Mallo-
phagaj which have lost their wings, and there are insects that
have no wings at the time or in the form that we happen to
observe them — larvae and pupae and worker ants and apterous
mutants of winged forms. Therefore the possession of wings,
conspicuous insect characteristic that it is, has been discarded
as a character for the separation of insects from other forms.
The whole question is reduced to the much agitated one: Are
we going to give precedence to physiological or to morphological
characters in the classification of the bacteria?
Morphology of the sporangium has been used as a character by
a long succession of workers. Its use may be more vigorously
attacked than that of the other characters. It was introduced
530 HILDA HEMPL HELLER
by strict morphologists (Zopf, Fischer) entirely independently
of any physiological criteria, and in this way was quite justifi-
able because by its use a superficially consistent division could
be made. The rods which did not swell at sporulation formed
one group, those which did swell formed another. But Kruse
and the Conmiittee have superimposed upon this tjrpe of classi-
fication a physiological one, and the result is a division that it
is impossible to carry out. Probably more aerobic rods fail to
swell at sporulation than do anaerobic rods, but the exceptions
to this rule are so numerous on both sides as to render worse
than useless the employment of the morphological character in
connection with the physiological one. The reader is referred to
the illustrations given by Ford and his co-workers and by von
Hibler (1908) and by the Medical Research Committee.
The position of the spore has been used by several authors in
subdividing the anaerobes. Species of anaerobes have very
characteristic ways of sporulating. But the position of the spore
may vary in one species within limits wide enough to render its
use exceedingly inadvisable as a character for the grouping of
genera. One may take as a single illustration the behavior of
a pure strain of vibrion septique. Vegetative forms are fairly
uniform on most media. Sporangia, however, show in their
variations all the characteristic forms described by Fischer, by
the Committee, and by Buchanan. They are, on meat medium
(forty hours' culture), usually thickened in the center with the
typical form of Clostridia. But some rods may contain spores
and still have parallel sides, and forms with sub-terminal and
terminal spores are nearly always to be found. On serum media
the vegetative rods may vary greatly in their proportions, the
sporangia assume many fantastic shapes, and '^drumstick"
forms are common. On the liver of animals the vegetative rods
form enormous thick filaments: some strains may sporulate with-
out at all changing their outline or may form Clostridia, and
some, identical with the first in morphology on ordinary media,
may, on the liver of animals, show club-shapes that resemble the
clubs formed by the actinomycetes, while others form great
globoid masses, terminally or mesially placed in the rods. Rarely
CLASSIFICATION OF ANAEROBIC BACTERIA 531
three or four spores may occur in a rod which has remained
undivided. In fact the only fixed morphological character to
be noted is the shape of the spores, which, so far as I know, in
this species everywhere remains oval. This is the sole morpho-
logical character that was noted in my anaerobic studies that
cannot be assailed as inconstant, yet the shape of the spore is a
character that has been consistently overlooked by classifying
morphologists, who have chosen instead the extremely variable
one of spore-position.
The size of the rod has not been mentioned by most classifiers.
In general the sporulating rods are larger than the non-sporu-
lating rods. But to reduce this generalization to definite meas-
urements as Lehmann and Neumann have done is not a practical
procedure.
The arrangement of the badlK in chains is not significant.
Probably the aerobes form chains more frequently than do the
anaerobes, but filament formation cannot logically be used as a
character for their dififerentiation. Winslow and Winslow found
chain formation a character of minor value in the classification
of the streptococci. Certain organisms, e.g., B. Novyi, regularly
form filaments on certain media, but the character is of specific,
not of generic, value.
Morphology of colonies would be mercilessly discarded by
experimental workers as a means of subdividing a large group
like that of the Badllaceae. It has more value for lower sub-
divisions.
The Gram-^tain is an impossible character to use in dividing
the Badllaceae. It fits neither with the morphological char-
acters nor with the physiological. There are numerous Gram-
positive anaerobes and aerobes, and numerous Gram-negative
anaerobes and aerobes. (See Heller, 1920.)
GraniUose (logen) content of the bacterial cells cannot be
seriously considered as a general character of anaerobic rods.
Habitat. Winslow and Winslow found that the Coccaceae
could logically be divided according to habitat. The parasitic
forms constituted one group and the saprophytic ones another.
Certain anaerobes are frequently inhabitants of the intestines
532 HILDA HEMPL HELLER
of animals. But this tjrpe of character has not been worked out
for the anaerobic organisms and should evidently not be used
in classification until it has been investigated thoroughly. In
view of the fact that a large variety of anaerobes are to be found
in soil it is not advisable to state that anaerobes are ''often
parasitic." Habitat might be used conservatively as a descrip-
tive character.
The formation of toxin and the pathogenicity for animals — the
most interesting of characters to the majority of us — cannot
logically find a place in the higher divisions of our group. They
become of more systematic value in classifying genera and
species, but they should always be used in connection with
other characters. Jensen's grouping of B, tetani and B, botulinus
in the genus Botuhbacillits because both produce toxin is not
advisable. The toxins produced by these organisms are dia-
metrically opposite in their effect on nerve tissue and that of
B. hotulinus and probably that of B. tetani are entirely adventiti-
ous so far as a parasitic mode of life is concerned. Other anaer-
obes of different affinities form toxins that produce stiU other
and different effects.
We have seen with what ease objections may be made to
ahnost any morphological character used for the division of the
rods of higher metabolism, in case any physiological character
is allowed to enter into the classification. We have stated also
that some of the proposed morphological characters are not
sound for single species or even for a given cultiu'e of a single
strain. As Breed, Conn, and Baker say, the future must decide
what type of character, physiological or morphological, will
predominate in the classification of the bacteria. The two
systems are so often contradictory that they can never exist
side by side. One must always be used as the chief deciding
factor, the other as an auxihary which may, at any time, give
precedence to the former.
Experience with a single group may be misleading. The
higher plants, and even the fungi, may be satisfactorily classi-
fied on a purely morphological basis. At present the systematics
of bacteriology are so tentative that the matter must be left to
CLASSIFICATION OF ANAEROBIC BACTERIA 533
the judgment, or shall we say to the taste, of those who have
themselves worked with the groups that they discuss. I am
totally unable to see how morphological criteria can possibly
be used to any logical end in the classification of the rods of
higher metabohsm, or even of the main groups of anaerobes.
In 1902 Achalme found morphology of absolutely no use for the
differentiation of anaerobes. In 1905 von Hibler energetically
decried the use of morphology in anaerobic classification. In
analysis of the anaerobic group morphology has its place, and
can logically be used to distinguish types that are otherwise
similar. It can not, in my opinion, be used to unite groups
that are otherwise dissunilar. In the anaerobic group morpho-
logical criteria alone would hopelessly bewilder the student and
lead him to the correlation of fundamentally different types and
to the separation of sister rods of the same strain. Morphology
need, however, never be entirely discarded from classification.
The morphology of the anaerobes is, for a given species, so
characteristic, that if it be observed conscientiously, and if the
worker does not generalize too freely in formulating his descrip-
tion, it may well be used as a valuable descriptive character for
species, and as an auxiliary character for the description of
genera. It is in organizing the major groups of anaerobes that
morphology fails us. Professor Harvey M. Hall of the Botany
Department of this university suggests that after a logical and
fundamentally historical chemical classification has been made,
morphological characteristics will be found which will be con-
sistent with it. One must distinguish between different t3T)es
of morphological criteria. Gross form of rod and position of
spore are not fundamental morphological characters: they vary
greatly within the species. But a highly refined cytological
technique such as has never been generally applied to our organ-
isms might reveal consistent morphological characters.
THE ANAEROBIC RODS
In my opinion the most logical division of the bacterial rods —
the rods which split higher compounds and are not acid-fast —
is the physiological one of susceptibiUty to free oxygen. Ability
534 HILDA HEMPL HELLER
to live in the absence of free oxygen has been developed by too
many types to make it a character of value. But fewer types
have developed a susceptibility to free oxygen. The classifi-
cation proposed by the Committee (1920) places certain anaerobic
forms such as the anaerobic leptotrichia with aerobic forms that
are patently their relatives. The Committee justly assigns
generic rank to the obligately parasitic, non-sporulating, shyly
growing, fusiform anaerobes. They do not mention the anaero-
bic cocci, which should probably be included with the Coccaeeae.
The Committee does not mention any anaerobic non-sporulating,
non-fusiform rods. In my collection there are two such strains
(B. egens and one of my own isolation) which do not readily
attack milk, and these organisms do not fall into any of the
groups designated in the key, which follows the Committee's
classification. B. necrophorusy again, of whose phylogenetic
position I am in doubt, does not sporulate.
Fusiform bacilli have probably recently acquired an anaerobic
habit through parasitism. Thus Larson and Barron describe a
strain of these organisms which became adapted to growth under
aerobic conditions. Analogous is the behavior of B. abortus-
hovis, which frequently refuses to grow aerobically when first
isolated but later accustoms itself to living in the presence of
oxygen. The anaerobic habit may, in some cases, be due to a
sensitiveness to carbon dioxide instead of oxygen. Curtis has
described a motile curved anaerobic rod which he isolated from
uterine discharges. The phylogenetic position of this organism
is in doubt. So also is the position of the branching anaerobes
B. ramosus and B. furcosus of Veillon and Zuber, and the influ-
enzarbacillus-like rod isolated from an abscess by Russ. Tunni-
cliff reports anaerobic rods from rhinitis and from bronchitis
patients; and Tunnicliff, Plotz and his co-workers, and Dick
and Henry, report anaerobic organisms in the blood of fever
patients. But these organisms grow slowly and do not resemble
the chemically active anaerobic rods. We are justified in con-
cluding that an organism which has lived as a saprophyte or
parasite in the tissues or in the uterus may owe its anaerobic
habit to such residence. There are several reasons why we should
CLASSIFICATION OF ANAEROBIC BACTERIA 535
hesitate to attribute to a parasitic or intestinal saprophytic
history the anaerobic habit of the rods found commonly in soil.
These rods are abundant in unmanxired soil, their species are
very numerous, their metabolic processes exceedingly varied.
They may grow under aerobic conditions in company with aero-
bes and may grow in the presence of oxygen in pasty or solid
material or in liquids containing soap or other substances which
alter surface tension. But they retain their anaerobic habit
on clear liquid or agar media. The commonest intestinal organ-
isms, those of the colon group, have not assumed a sensitiveness
to oxygen. Many of the anaerobes, such as those of putrificus,
sporogenes, and bifermentans affinities, are the common agents
of putrefaction outside the animal body, while others described
by Omeliansky are the common cause of the decay of cellulose.
When parasitic outside the intestine, these organisms usually
show little of the character of true parasites, but cause fulminat-
ing fermentative processes which, do not pass from affected
individuals to healthy ones. B. ahortus, the anaerobic strepto-
cocci, fusiform baciUi, and certain types of B. coK, when they
invade the tissue may establish chronic infections, characteristic
of highly developed parasites, but the anaerobic rods common
in soil do not, so far as we know, behave in this manner. They
are apparently unable to establish themselves as chronic para-
sites in tissues which are well vascularized. Had they a history
of intestinal saprophytism, we should probably find highly
adapted parasites among them, and should find it easy to educate
them to an aerobic habit.
No one has, of course, suggested that the nitrogen-fixing
anaerobes described by Winogradsky developed their anaerobic
habit through parasitism. These organisms are active splitters
of carbohydrates. They are usually regarded as primitive. It
is more probable that the anaerobes of higher metabolism had
an evolution of the following type rather than one from the
sporulating aerobes or from intestinal saprophytes of large
animals which appeared at a comparatively late geological
period.
536 HILDA HEMPL HELLER
Nitrogen-fixing anaerobes that split carbohydrates. E.g. Clm-
tridium Pastorianum Winogradsky, a large anaerobic rod that
forms oval spores.
Carbohydrate-splitting anaerobes that can utilize fixed nitrogen
but not free nitrogen. They do not produce gross proteolysis.
E.g. vibrion septique.
Anaerobes that split proteins very actively. Some but not all
have lost the power of splitting carbohydrates. -E.g. the sporo-
genes type.
Geologically this sequence would be the most natural. But
we know so little about bacteria and their evolution that any
evolutionary arrangement is little more than guess-work at the
present time.
It is my intention to propose a division which seems more
logical than "the Bacillaceae, spore-bearing rods," as dis-
tinguished from the ^^Bacteriaceae, non-sporulating rods of higher
metabolism." This division implies the creation of a family:
''The Chstridiaceaey rod-like forms, not spiral, which will not
grow within seven millimeters of the surface of a shaft of clear
tissue-free agar mediiun contained in a tube 12 millimeters or
more in diameter, incubated in air, in which they are able
to grow in the depths. They may or may not possess peritrichial
flagella; they may or may not form spores. Most members of
the group are characterized by their energetic action on proteins
or on carbohydrates or on both of these types of substances."
It would be unwise to claim that we have evidence to show that
these organisms are descended from a single type — in other
words that this is a perfectly logical classification. Bacteriol-
ogists have no characters available for purposes of classification
whose nature is sufficiently understood to grant us the liberty
to make such assumptions. But I believe that this primary
division will separate fewer types that are physiologically alike
than any other thus far proposed. The energetic action of the
anaerobic non-fusiform rods upon carbohydrates and proteins
is characteristic and separates them from most other groups.
In the present state of our knowledge it is only the separation
of types that have several characters in common that is care-
CLASSIFICATION OP ANAEROBIC BACTERIA 537
fully to be avoided. The bacterial characters understood by
us are so elementary that we can, as yet, have no assurance
that we are not at times uniting types that have not the same
ancestry.
It will be noted that the Committee has arranged the bacteria
into orders, families, and genera. Most families have also been
divided into tribes. The genera of the Actinomycetales have not
thus been arranged in tribes, because their relationships are
avowedly obscure. But the sporulating rods have been given
the very inferior position of two genera and the tribal relation-
ships are not expressed. This is because these organisms have
been so slightly studied. As Ford says in his introduction, our
knowledge of the spore-bearing bacteria is still in a state of
chaos. The sporulating organisms, at least the anaerobes, are
legion in species, and form a group that is to be divided and
subdivided.
Whether or not the aerobic spore-bearers (genus BociUils of
the Committee) form a homologous family, I am unable to say.
Compared with the anaerobic rods they are apparently very
few in number of species. Ford and his co-workers list twenty-
eight species which they place, on the basis of morphological
and gross cultural characters in nine "groups." These groups
would probably form as logical genera as some of the others
which have been recognized.
It may be asked why tribal rank should not be assigned to
the anaerobic and aerobic rods instead of family rank. It would
seem that the group of anaerobic rods is sufficiently large, pecul-
iar, and important, to warrant its being given family rank.
Probably none of the botanical or zoological families contain
nearly as many species as may be found among the anaerobic
rods. On strict analogy with botanical and zoological classi-
fications the anaerobes should command an order at least, but
being unfortunately dogmatically confined in our classification
to a single class which must include all one-celled cellulose-
and chlorophyll-free plants that divide by simple fission, we must
be modest in our demands.
538 HILDA HEMPL HELLER
In order to ensure a natural classification, characters mu^t be
worked out for each group, characters that will to some extent
correspond, and show by such correspondence or by the lack
of it where lie the historical divisions and where the parallel
developments that have taken place independently. This alone
is a great labor. For the group of the anaerobic rods and for
many other groups nothing of the sort has as yet been seriously
attempted. The Winslows' classification of the Coccaceae, a
pioneer work in this direction, has appUed several principles,
which may well be heeded in making future classifications.
These authors appUed to 500 strains of cocci from various sources
the biometric principles in use by students of heredity, by anthro-
pologists, and to some extent by botanists and zoologists. Upon
a study of the tabulated figures based on the behavior of these
organisms they formulated their determination of what to call
a species and of how to group species into genera. They found,
in common with botanists and zoologists, that when abundant
material is at hand it is quite impossible to define as a species
one single type. If oxu* methods were sufficiently refined we
could probably distinguish every bacterial strain from every
other, just as we can distinguish every hmnan being from every
other. A species is finally to be determined by comparing the
characters of aggregates of individuals (higher plants and ani-
mals) or of strains (bacteria), and by selecting the types which
occur most frequently as the standard upon which to base specific
descriptions. The conclusions arrived at by Winslow and Wins-
low as to analysis of their data are as follows :
First, each center of numerical frequency, marking a group of organ-
isms varying about a distinct type in regard to a single definite pro-
perty, may be recognised as a species. Second, those species which are
bound together by the possession of a number of similar properties
may be constituted as genera, and larger groups of genera, still charac-
terized by some characters in common, may receive the rank of families
or subfamilies.
This method of working is evidently very different from the
old method whereby one man described one strain and another
CLASSIFICATION OF ANAEBOBIC BACTEBIA 539
man another, and a third decided some ten years later from their
descriptions whether they were working with the same or with
different species. The biometric method is evidently true biology,
while the other is a process of cataloging. The principles of the
biometric . method are those that one would choose to follow,
even though one were unable to make a study of so extensive a
series as did Winslow and Winslow. But it is upon the first
method, that of collation of descriptions from the literature,
that our comprehensive classifications have so far been made.
This has led to a complete misunderstanding of the nature of the
anaerobic group. A few anaerobes have been described, most
of the descriptions being wholly inadequate for purposes of
specific determination. This fact has in no way deterred workers
from making identifications. Some of these mistaken identi-
fications are now thoroughly ingrained in the literature, for
example the use of the name putrificus in Germany for the
svcyrogmes type of organism, when there is a different definite
tjrpe existent which corresponds far more closely to Bienstock's
description of B. pvirificus. The names of some of the de-
scribed anaerobes have been accepted, and if these tjrpes are
pathogenic or very common they find their way into the text-
books. Textbooks mention usually five anaerobic organisms:
B. tetani, B. hotulinusj B. oedemalis'-maligni, B. Welchii, and
jB. Chauvoei. So far as I can see the classifications are largely
based on a conception of the anaerobic world which knows few
forms but these. But the worker with "wild" material can
easily pick up and isolate two or three new species of anaerobes
a day for an almost indefinite period. Few workers now pay any
attention to non-pathogenic anaerobes, knowing that their path
would be crossed by so many new species that no end but the
mere description of new species would be attained. But these
undescribed forms are just as important, theoretically, to the
systematist, as are the pathogenic ones.
The ideal way of classifying anaerobes would be a biometric
one carried out on a scientifically adequate number of strains.
But it will be years before sufficient interest in the anaerobes
exists to warrant the collection of any such material. The labor
540 HILDA HEMPL HELLEB
of making such collections and of keeping close watch on all
strains to insure their purity is tremendous. The bacteriologist
is not the only systematist who has to do with such a problem
as ours. The classifier of the Coccaceae is in the position of the
curator of a museum who has before him the skins of a hundred
or two of squirrels or other rodents, their measurements and
habitat given, their skulls freed of muscle reposing in tiny bottles
by their sides. The classifier of the anaerobes is today in the
position of the exploring zoologist who sets his traps at night
on his journey and catches one or two or three new rats or mice
that do not resemble any thus far met by him. Both men
describe new species and both serve science in so domg. But
the museum worker may use as his type-species the animal whose
characters are an average of those of all the rest, while the
exploring zoologist must call the "tjrpe^' one of his chance catches
which may be a freak in one or more ways. And yet we would
not have the explorer place his mice from a far country nameless
in a museum for a future zoologist to describe some seventy-
five years hence when the far country has been settled and the
mice have been caught by the hundred.
The problems presented in the classification of the Coccaceae
and of the Clostridiaceae are quite different in other ways. The
anaerobes form a group of far more diverse tjrpes of organisms,
both from the morphological and from the physiological stand-
point, than do the cocci. One may say that their characters are
more salient, more easily perceived, or more definite in their
nature, than are those of the cocci. Or one may state with
equal truth that the anaerobic group is a less homogeneous one
than that of the cocci. One would also be justified in stating
that the anaerobic species and genera are far more numerous
than are those of the Coccaceae. Therefore a representative
and adequate collection of anaerobic strains for statistical study
would have to contain not hundreds but thousands of strains.
But this element of distinctive characters places in our hands
a means for the determination of genera before we are familiar
with many strains of each genus.
CLASSIFICATION OF ANAEROBIC BACTERIA 541
SPECIFIC AND GENERIC CHARACTERS
No one will dispute that the decision as to the line between
specific characters and generic characters lies with the system-
atist who, though he have a previous knowledge of many other
groups, has confined his attention to one group, and not with
the systematist who organizes the published work of others.
In different groups these boundaries vary somewhat. But in
general the following definition will probably be accepted for
such types of material as we are unable to examine thoroughly
by a biometric method. Strains of bacteria that regularly and
consistently differ from each other in certain characters that we have
come to recognize as significant may be assigned to different species.
These characters may be quantitative in their nature. It lies in
the hands of each worker to decide what the value of these characters
is. An arrangement made without reference to biometric data
is in any case bound to be tentative. Generic characters are
based on qualitative properties. As a working system the follow-
ing classification of specific and generic characters for organisms
of the anaerobic group is suggested:
Generic characters, qualitative:
Qualitative chemical action: behavior on usual laboratory
media (excepting the fermentation of milk).
Staining reaction and general morphology of individuals.
General habits of colony formation.
Pathogenic action.
Specific characters y quantitative:
Quantitative chemical action: behavior on carefully standard-
ized media; hydrogen-ion end point attained as a result
of specific enzyme action.
Sugar fermentations if not subject to active mutation.
Peculiar habits of the morphology of individuals.
Exact behavior of colony formation on a standard medium.
Details as to pathogenic action.
In studying my material, I find abundant justification for the
application of properties of this sort. With such characters to
build upon, a more detailed structure, more exactly expressing
542 HILDA HEMPL HELLER
relationships, can later be erected. We are not yet ready to
declare where the limits of variation for the organisms of our
group may lie. ' But I am decidedly of the opinion that in general
the old conception of species as accepted for the anaerobic group
must in future be taken as the conception of genera, and that
we must be more exact in our examination and analysis of these
organisms. To do otherwise, and classify as the same species
organisms which regularly and consistently show marked quanti-
tative diflferences in their behavior, would be to distinguish our
system of classification sharply from those of the botanists and
zoologists and to set up oiu* own meanings of ' 'species" and
''genus." The application and use of the characters here sug-
gested will be described more fully in a future paper.
Perhaps the first-noted definite "character," splitting up a
so-called species into a nmnber of groups, is the agglutination
reaction. Thus Tulloch by this method demonstrated the exists
ence of four tjrpes of the group recognized under the name of
B. tetani. Robertson thus subdivided her vibrion septique
strains into foiu* groups, and Henry divided the species of B.
spoTogenes into two groups on the basis of the agglutination
reaction. It has been found by various workers that agglutinat-
ing anti-sera formed against various strains of B. Welchii do
not agglutinate heterologous strains of the same organism, though
Werner found a serum that agglutinated one out of several
heterologous strains. When one thinks, however, of the com-
paratively numerous cases of cross agglutination recognized in
other groups, some of which may, and some of which may not
be modified in their importance by absorption-of-agglutinin
tests, and when one considers the Weil-Felix reaction, one is
ready to look for a more highly specific character than that of
the agglutination reaction by which to analyze his strains.
The Medical Research Committee term the agglutination reac-
tion "ultra specific" (191*9). I personally regard this reaction
as of sub-generic rank, and not as of sub-specific rank in
the anaerobic group. The agglutination reaction has not yet
been investigated thoroughly enough to determine its value as
a systematic character for anaerobic bacteria.
CLASSIFICATION OF ANAEROBIC BACTERIA 643
NOMENCLATURE OF LOWER GROUPS
Our next concern relates to the nomenclature of our genera
and species. We are peculiarly hampered in bacteriological
work, when we try to base our names for organisms upon their
behavior or characters. Morphology is a notoriously bad bac-
terial character for generic names, though it has long been used
as a generic character for our primary divisions of the bacteria
{Coccus J Bacillus J SpiriUum) and apparently has a sound basis
in this case. Pathogenic action is an equally misleading char-
acter upon which to base generic names : most anaerobes are not
pathogenic and of those that are, various groups produce gas,
oedema, haemorrhagia, etc. Chemical action would be the best
type of character for descriptive purposes. But how often
might we not, in a group that is so enormous as that of the
bacteria, inappropriately name a new genus for a chemical
character that was possessed in a greater degree by other genera,
or was not possessed by all the members of the genus? There
is also a prejudice among botanists against the formation of
generic names from specific names, though such forms are not
unusual in zoological nomenclature.
Dr. Karl F. Meyer has suggested to me the use, for purposes
of generic nomenclature, of patronymics, preferably of the name
of the author first describing the original species of a genus.
This seems to me the most fitting and logical procedure. It
has ample precedent in botanical nomenclature, and has been
used in bacteriological nomenclature for years: e.g., PasteureUa,
EbertheUa.
Recommendation V.e. (International Rules for Botanical
Nomenclature, Chap. Ill, Sec. 3, No. 3) will, if heeded in the
formation of generic names, aid greatly in overcoming conserva-
tive objections to the new system of classification. This recom-
mendation reads: "To recall, if possible, by the formation or
ending of the name, the affinities or the analogies of the genus."
Thus in the group of the cocci, -coccus has been accepted as the
usual termination of the generic appellations; -badUus has never
been popular for such formations, probably on account of its
544 HILDA HEMPL HETJiEH
length. I had considered the ending -eUa as used in 1900 by
Ligni^res for PasteureUa, and by Buchanan for PfeiffereUa.
But -ella, like -ia, is a common ending for generic names among
the higher plants. Would it not, in view of the existence of
this recommendation, be appropriate to terminate the generic
names of bacillary forms with the ending -iUiLS (from B(ic-4Uiis)f
(Patron3rmics ending in vowels may drop the final vowel before
adding -illtis.) Perhaps the ending -^erium may also be found
appropriate for names created in subdividing the old genus
Bacterium. Specific names should be adapted from the original
specific name, if such is valid, and new species can, of course,
be named according to the will of the author describing them.
TYPE STRAINS
Because of the factor of variation in the habits of cultures,
because many species of organisms must be frequently trans-
planted to keep them alive, and because of the important r6Ie
played by contaminations, the custom, so long accepted by the
botanists and zoologists, of preserving in musemns type-speci-
mens of newly-described species, has never been popular with
bacteriologists. The facts as related to the anaerobic group
are as follows : No experienced investigator of anaerobes would
care unreservedly to turn over to anyone else his type-strains
for general distribution, because of the ease with which they
may become contaminated, and because of the difficulty that
the ordinary worker has in recognizing contaminations. The
rather generally disseminated view of Grassberger and Schatten-
froh (see Heller, (1920)) that the characters of anaerobes are
highly variable is one to which I cannot subscribe. This view,
which has cast a blight on modem German anaerobic studies
and caused grave misinterpretations (see Rahn), has also de-
terred workers from the use of type-strains to make their descrip-
tions definite. The anaerobic bacteria are fairly stable types
(when in pi|ire culture) and they have, in common with all other
organisms, that degree of variability which permits them to
adapt themselves somewhat to changing conditions and they
CLASSIFICATION OF ANAEROBIC BACTERIA 545
may, occasionally, show mutations as do all living organisms.
The problem of their variability is essentially no different from
the problem of the variability of other bacteria. Their behavior
toward proteins is remarkably constant, while their action on
carbohydrates is somewhat variable.
THE SUBDIVISION OF THE CLOSTRIDIACEAE
We have now outlined the status of the anaerobes in bacterial
classification, and the position to be held by genera and species.
It remains to organize the structure between the generic rank
and the family rank. It is here that we have the most need of
allowing room or elasticity for the convenience of future system-
atists whose information will be greater than ours is today.
With our present knowledge I do not think that we are entitled
to make more than one main subdivision of the Chsiridiaceae.
This division should follow that made by von Hibler in 1899,
in 1905, and in 1908. Von Hibler showed that some anaerobes
produce more acid than alkali on certain media, while others
produce more alkali than acid. On the basis of this observation
he classified the fifteen species studied by himself into two
groups. He titrated brain cultures and milk cultures against
1^^ HCl and KOH^ and found that on both media the organisms
of the first group produced an acid reaction, while on brain
medium, which is poor in sugar, the organisms of the second
group invariably produced an alkaline reaction, and on milk,
though some of them at first produced an acid reaction, they
all finally gave an alkaline end point. The production of an
alkaline reaction was always associated with peptonization of
milk and was usually associated with a blackening of brain
medium and with the production of hydrogen sulfide. The
organisms that produced and maintained an acid reaction in
milk and brain never peptonized casein or blackened the brain
particles.
The division thus made by von Hibler has been accepted and
followed by Jensen and by various anaerobic workers. The
alkali-producing group is termed proteolytic or putrefactive ^ the
546 HILDA HEMPL HELLER
acid-producing group noiv-proteolytic or aaccharolytic. The orgaa-
isms studied by von Hibler were all energetic in their reactions.
B. Novyi and organisms related to it, such as B. oedemcUiens^
form hydrogen sulfide m blood media and do not produce mudi
acid in milk. They do not peptonize casein or blacken or
putrefy meat. They and the Bifennentans tjrpe and certain
other organisms that I have encountered do not fit so nicely into
von Hibler's scheme that we can safely place them in either
group without drawing a dogmatic line and measuring their
activities accurately. Douglas, Fleming, and Colebrook de-
scribe a sporulating anaerobe, B. cochlearius, which shows no
marked properties that unite it with either of von Hibler's groups.
It therefore seems advisable to define conditions imder which
anaerobes may be tested to determine their affinities with these
two groups. Objection may be made to such a separation of
the anaerobes on the grounds that when borderline organisms
are in question it is but a cataloging process to separate them.
Perhaps so, but when a classification is developing as is this
one and when so very few borderline forms are known, a catalog-
ing classification is better than none; later a group containing
these organisms may be formed if necessary. Moreover the
vast majority of anaerobes do fall definitely into one or the
other of these two groups and can be placed where they belong
on the basis of their behavior on ordinary media.
The requisites governing the selection of a medium for such
a pmpose are definite. In the first place all anaerobes must
grow upon it. Blackleg organisms usually refuse to grow on
simple sugar media. In order to give the organisms a good
start, and to furnish material for the formation of acid, our
medium should contain a little sugar, of the sort available to
the greatest possible niunber of anaerobes: glucose is probably
the sugar which best fulfills this requirement. But this sugar
should be Uttle in amount, and sufficient protein should be
present, so that the acid formed from the sugar may not inhibit
the growth of the organisms and prevent them from carrying
the reaction back to an alkaline end point if they are C£^able of
so spUtting protein that they produce such an end point in the
absence of acid.
CLASSIFICATION OF AKAEBOBIC BACTEBIA $47
Probably tissue-containing media best fulfill the above require-
ments. They need no more glucose than that which they derive
from the tissue contained in them. Brain medium as used by
von Hibler would be excellent were it made up with sufficient
liquid for titration purposes. Von Hibler titrated liquid from
his brain medium with litmus against potassium hydrate or
hydrochloric acid. Today workers would prefer to use a hydro-
gen-ion determination, for which a fairly clear Uquid is neces-
sary in case the simple colorimetric method is employed. Brom-
thymol-blue is a suitable indicator for making this separation.
At present most laboratories use the beef-heart medium intro-
duced by Robertson and Martin for anaerobic study because it
has many technical advantages over brain medium. It should
preferably contain about 5 per cent of peptic digest broth and
should be made with twice its weight of distilled water and tubed
in large tubes in order that enough liquid may be present for
hydrogen-ion determinations on several occasions.
Ten days' incubation at 37® will be found quite sufficient in
most cases for such a determination as we wish to make. Von
Hibler found the reaction decidedly acid or alkaline in brain
medium after five days. But to allow time for weakly proteo-
lytic organisms which form acid from glucose, to carry the
reaction over to the alkaline side, we should incubate the cul-
tures for twenty days at least. Such organisms do not at first
produce gross signs of putrefaction, but their proteolytic tenden-
cies may be tested for by the lead acetate test for hydrogen
sulfide. There may be soil anaerobes which do not grow at 37®.
Time and temperature for incubation will have to be decided
upon for such organisms separately in case they are found.
Von Hibler (1908, p. 88) found that with his pasty brain
mediimi the mode of incubation, aerobic, or anaerobic in hydro-
gen or in carbon dioxide, made no difference in the reaction.
But if we are to use a medium with .a considerable amount of
Uquid on the surface it would probably be xmwise, even though
anaerobes grow in the medium with the surface open to the air,
thus to incubate our organisms for twenty days. An anaerobic
method should be employed. The simplest method available
548 HILDA HEMPL HELLER
to most laboratories is stratification with vaseline. After
incubation the culture should always be boiled to expel carbon
dioxide.
For pure culture study the exact point of the reaction of the
medium at the time of inoculation is not important. It is
important only that the reaction should be well within the limits
for growth of the organism studied, and not very far from neu-
trality. A reaction of pH 7.2 (neutral to litmus) has been used
in this laboratory for most anaerobe media. The selection of a
reaction point for the dividing of the two types of anaerobes is
more difficult. Von Hibler (1908, pp. 89, 104) used the neutral
point of litmus. The selection of a dividing point in meat
medium is frankly an arbitrary affair. I suggest pH 7.0, the
neutral point of hydrogen-ion concentration, for the dividing
line between the alkali-producing and the acid-producing
anaerobes.
It is imlikely that any other division of tie Closlridiaceae
will be made which would be placed above the division into the
two groups just described. But I am certain that various
arrangements of the genera which compose these groups will
in time be made. There are many anaerobes that behave quite
aUke in one way and entirely differently in other ways. If
this were to be a final classification of the group, or if one wished
to outline a temporary classification, one would give the division
into putrefactive and non-proteolytic anaerobes a tribal rank.
But I am quite certain that the makers of future arrangements
will want very much to utilize tribal and subtribal ranks for
other purposes. I had myself thought of dividing the non-
proteolytic anaerobes into two tribes or subtribes on the basis
of presence or absence of flagella, but Dr. M. Christiansen has
repeatedly been unable to demonstrate flagella on his whale-
septicaemia bacillus .which so closely resembles the vibrion-
septique type of organism. that they should probably be placed
in the same genus. But tribal and sub-tribal classifications are
sure to be made by someone before long and it will be a better
provision for the future to give the proteolytic-non-proteolytic
division sub-family rank.
CLASSIFICATION OF ANAEKOBIC BACTERIA 549
I propose, therefore, the two subfamilies,, Clostridioideae and
PutrificoidecLe.
Clostridioideae: Clostridiaceae which on meat medium produce
after twenty days' incubation under oil at 37° a reaction of
pH 7.0 or a more acid reaction, the reaction being read after
the culture has been boiled.
Pvirificoideae: Clostridiaceae which on meat medium produce
after twenty days' incubation under oil at 37® a reaction of pH
7.1 or a more alkaline reaction, the reaction being read after
the culture has been boiled.
The name Clostridioideae is derived from Prazmowski's generic
name Clostridium. The name Putrificoideae is formed from
the specific name putrificus (Bienstock 1884). (JPutribacilhis
vulgaris of Jensen.) We are hard put to it to find sufficient
generic names upon which to form appellations for higher groups
in the anaerobic field because Bacillus was the generic name
applied to any and almost every rod described. But I think
that bacteriologists will be justified in using ancient specific
names for the formation of the names of tribes and families.
Such a proceeding would have a basis in logic if not in precedent.
The name Pvirificus has probably been used for various organ-
isms of the same genus (as well as for those of other genera)
and is as much a generic name in sense as though it had been
originally designated as such. I should, for example, on finding
a slender proteolytic rod that formed terminal oval spores and
did not spUt glucose or other sugars, term it pulrijicus type,
knowing that more organisms might be found that corresponded
to such a description but that would probably not be specifically
identical (see Rodella). Bienstock himself refers to his organ-
ism as B, puiriJUms and as Puirifums (1899).
A Suggested Classification of the Anaerobic Bactebia
Phylum 1. Bacteria (Nov. phyl.): Simple one-celled plants that multiply
typically by binary fission and occasionally by budding.
They show no form of sexual multiplication. They rarely
contain cellulose and do not contain chlorophyll or phycocyanin.
Class 1. Evbacterieae.
Class 2. (Myxohacierieaet Bacteria which join to form a complex fruiting
body (see Vahle, p. 196)).
550
HILDA HEMPL HELLER
Class L
Order 1.
Order 2.
Order 3.
Order 1.
Family 6 (?)
Subfamily 1,
Subfamily 2.
Eub€xUrteae: Bacteria which do not fonn a complex fruiting
body.
Eubacteriales,
(TkiobactertaUa, sulphur bacteria.)
(Chlamydobacteriale8f iron and manganese bacteria.)
EubacUriaha: Eubacterieae whose cells are never in sheathed
filaments. Conidia not observed. Free iron, sulphur, or
bacteriopurpurin never present. Multiplication always occurs
by transverse fission. (Committee)
Clostridiaceae (nov. fam.): Ettbacterialea that are rod-like, not
spiral, that will not grow within 7 mm. of the surface of a shaft
of cleaY* tissue-free agar medium contained in a tube 12 milli-
meters or more in diameter, incubated in air, in which
they are able to grow in the depths. They may or may not
possess peritrichial flagella, they may or may not form endo-
spores. Most members of the group are characterized by their
energetic catalytic action on proteins or on carbohydrates or
on both of these types of substances.
Cloatridioideae (nov. subfam.): Clostridiaceae which on meat
medium produce after twenty days' incubation under vaseline
at 37° a reaction of pH 7.0 or a more acid reaction, the reaction
being read after the culture has been boiled.
Type genus Rivoliillus (nov. gen.), the vibrion septique type
as described by Heller.
Putrificoideae (nov. subfam.): Clostridiaceae which on meat
mediimi produce after twenty days' incubation at 37** under
vaseline a reaction of pH 7.1 or a more alkaline reaction, the
reaction being read after the culture has been boiled.
Type genus MetchnikovUltts (nov. gen.), the sporogenes
types as defined in the description of BacUltks sporogenes,
described by the Medical Research Committee as Metch-
nikoff's type A.
SUMMARY
1. Morphological criteria cannot be used in classifying the
higher groups of anaerobes.
2. The anaerobic rods may logically be placed in a common
family on the basis of the physiological character of sensitive-
ness to free oxygen.
3. This family may be subdivided into two sub-families on
the basis of chemical action on carbohydrates and proteins.
4. The divisions "tribe'' and "sub-tribe" may well be left
open for future organization.
CLASSIFICATION OF ANAEROBIC BACTERIA 551
5. The old conception of species in the anaerobic group cor-
responds to the general systematists' conception of genera.
Generic characters may be based chiefly on qualitative behavior
on ordinary media. Pathogenesis and general morphology may
be used as auxiUiary generic characters.
6. Specific characters may be based on sugar fermentations;
on quantitative chemical action, on the morphology of colonies
and to some extent on the morphology of individuals.
7. We are not as yet ready for extensive biometric determina-
tions in studying many of the anaerobic groups and must tempo-
rarily adopt a more easily performed technique for the distinction
of these organisms.
8. A classification of the anaerobic group is proposed whose
details are to be elaborated in a following paper.
I wish to extend my hearty thanks to Dr. K. F. Meyer and to
Dr. Harvey M. Hall for reading the manuscript of this paper
and for making many wise and helpful suggestions which have
been followed in its compilation.
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CLASSIFICATION OF ANAEROBIC BACTEBIA 553
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HYDROGEN IONS, TITRATION AND THE BUFFER
INDEX OF BACTERIOLOGICAL MEDIA
J. HOWARD BROWN
From the Department of Animal Pathology of The Rockefeller Institute for Medical
Research, Pririceton, New Jersey
Received for publication April 19, 1921
Of recent years bacteriologists have become familiar with the
determination of hydrogen ion concentration as applied to the
problems of bacteriology. In many if not most laboratories
media are properly adjusted to certain hydrogen ion concentrar
tions, and the changes in reaction produced by the growth of
organisms in these media are likewise determined in terms of
hydrogen ion concentration. It has been repeatedly pointed out
that media of the same titratable acidity or alkalinity may differ
widely in their actual or true acidity or alkalinity. It is known
that an acid-forming organism growing well in the presence of an
excess of fermentable sugar in different bouillons may arrive at
approximately the same final hydrogen ion concentration in each
medium, whereas the titratable acidities of the cultures may
differ widely. Who of us has not been confronted repeatedly
by such questions as — ^Why do you titrate your cultures? Is not
the true acidity found by the determination of hydrogen ion
concentration and is it not much simpler? Why bother with
titration? To which the answer is — ^Yes, but titration and
hydrogen ion determination tell entirely different stories: they
are not simply two methods, one more accurate than the other,
of determining the same thing.
The committee on the Descriptive Chart of the Society of
American Bacteriologists (1919) has published the statement
that "the titration method (is) entirely illogical for adjusting
the reaction of media or for determining the amount of acid
produced by an organism." To both parts of this statement
555
JOCBNAI. OF BACTSBIOLOOT, VOL. VX, NO. 6
566 J. HOWABD BROWN
exception must be taken. The inaccurctcies of the titration of
media, aB it has been commonly practiced in the past, are well
known and it is agreed that the reaction of media should be
adjusted to certain hydrogen ion concentrations. Nevertheless
the committee's condemnation of titration seems entirely too
sweeping and therefore misleading.
When one takes a sample of medium and determines how much
acid or alkali must be added to bring it to a certain hydrogen
ion concentration he performs a titration, though he may choose
a better indicator than phenolphthalein and may determine
the end point by comparison with a color standard in a compara-
tor block, or may determine the end point electrometrically.
If one wishes to determine the reaction of a culture, he must
make a hydrogen ion determination, but if he wishes to determine
"the amount of acid produced by an organism" he must titrate
the culture with a strong alkali, precisely because in a well buff-
ered medium much of the acid formed enters into combination
with buffer substances and is not revealed by a hydrogen ion
determination.
It has been claimed by H. M. Jones (1920b) that various
factors may influence the final hydrogen ion concentration of a
culture. Similar conclusions were reached by F. S. Jones (1920)
who regards titration under well controlled conditions as quite
as satisfactory as the method of determination of hydrogen ion
concentration for the study of the fermentative activity of strep-
tococci. The first mentioned author states that ''the amoimt
of glucose which a given organism can consmne is influenced by
the buffer content of the medium . . . which aids in
holding the concentration of hydrogen ion from the toxic limit,
thus permitting a larger amount of sugar to be decomposed."
It follows that in a poorly buffered mediiun the fermentation
of very little glucose is required to raise the acidity to the toxic
limit and that therefore in such a medium the presence of a
small amount of glucose, as an impurity in a test substance may
be a very disturbing factor. The possibility is illustrated by
the following experiment.
HYDROGEN IONS, ETC.; OF BACTERIOLOGICAL MEDIA 557
A culture of Bad. colt in Bacto bouillon (poorly buffered) plus 0.1
per cent glucose reached a hydrogen ion concentration of pH 4.8 in
24 hours and remained at this acidity during incubation for 5 days.
On the other hand a similar culture in a highly buffered fermented
veal infusion bouillon plus 0.1 per cent glucose showed a slight increase
in acidity up to 48 hours and then became progressively alkaline reach-
ing a hydrogen ion concentration of pH 8.5 in five days.
It is conceivable that there may be encountered an organism
of very low acid tolerance (e.g., pH 6.0 or 6.5) but which may
be an active fermenter of various carbohydrates so long as the
hydrogen ion concentration is kept down by a well buffered
medimn. In such a case titration would reveal a considerable
amount of acid formed whereas the final hydrogen ion concen-
tration would lead one to believe that little or no fermentation
had occurred unlesa the buffer content of the medium was well
known.
To be impressed by the importance of a knowledge of the
buffer content of media one needs only to note the frequent
references to it in the literature, notably the papers by IQigler
(1916), Berman and Rettger (1918), Bronfenbrenner and
Schlesinger (1918), H. Jones (1920a) and Wolf (1920). Most of
the discussion between the protagonists of titration and those of
hydrogen ion determination centers about the question of buffer
substances. By the use of a color standard of known hydrogen
ion concentration and a comparator block the titrationist need
no longer be embarrassed by the variable personal equation in
judging a poor end point, but to both the titrationist and the
hydrogen ion determinist the presence of variable and unknown
amounts of buffer substances in media constitutes a real
diflSculty.
A complete analysis of the reaction between buffer content
and growing culture would require a detailed knowledge of the
metabolism of the particular organism being cultivated, taking
into consideration the fact that the buffer content itself may be
modified by the culture. Nevertheless an index of the buffer
content at the beginning or at any time during the growth of
the culture is readily obtained by titrating the medium with
558 J. HOWABD BROWN
standard acid or alkali from one known hydrogen ion concentra-
tion to another. In the determination of such an index two
factors must be more or less arbitrarily selected, the limits of
hydrogen ion concentration between which titration is to be
performed, and the acid or alkali to be used.
Clark (1915b), Bovie (1915), and Clark and Lubs (1917) have
published titration curves of bacteriological media. From
these ciurves it is seen that if one starts with a medium of pH
8.0 or a little more alkaline and titrates with hydrochloric acid
to pH 5.0 the curve is practically a straight line. If a weak
acid such as lactic or acetic acid is used the curve begins to
flatten out slightly between pH '6.0 and pH 5.0, and markedly
after leaving pH 5.0 because of the lower dissociation constant
of the weak acids. The greater part of the range of hydrogen
ion concentration of bacteria of interest to the pathologist and
sanitarian lies between pH 8.0 and pH 5.0. This is also the
range of Na»HP04;=iNaHiP04. The acids formed in cultures
are mixtures of weak acids but within the range mentioned the
curves of acetic and lactic acid are almost identical with that of
hydrochloric acid. It would seem therefore that for the general
purpose of determining the relative buffer values of media hy*
drochloric acid may well be employed.
The '' buffer indices" of a number of samples of bouillon from
various laboratories have been titrated. The method has been
(1) to determine the hydrogen ion concentration of the medium,
which usually lies between pH 7.0 and pH 8.0, (2) 'to add suflS-
cient N/20 NaOH from a burette to reduce the reaction of the
sample to pH 8.0, and then (3) to the same or another sample
sufficient N/20 HCl to raise the hydrogen ion concentration to
pH 5.0. The amount of alkali required to reduce the hydrogen
ion concentration of a medimn from its initial reaction to a
stated lower hydrogen ion concentration, say pH 8.0, may be
called the "reserve acidity" (Washburn 1910) of the medium^
^ It is to be noted that the terms "reserve acidity," "reserve alkalinity*' and
"buffer index" are qualified by the pH values between which the titrations are
made. While the determinations here reported are for BI (pH 8-5), for certain
problems it may be advisable to adopt other limits of hydrogen ion concentration,
as for instance BI (pH 9-^) or BI (pH 5-3).
HYDROaEN IONS, ETC., OF BACTERIOLOGICAL MEDIA 559
indicated by the symbols Rh(pH n - 8) in which n = the ini-
tial pH. The amount of acid required to raise the hydrogen ion
The Buffer Index in tern* of per cent aoratl hydroeliloric aoid.
Q i J_j i 1 i 8 4 — i — I
TsxT-FiQ. 1. Graphic Rbpbesentation of thb BirrFBR Indices of a Nijmbbb
OF Samples of Bouillon
concentration from pH n to pH 5.0 may be called the "reserve
alkalinity" (Washburn 1910) of the medium indicated by the
s3mibols RoH (pH n - 5). The "buffer index" indicated by
560 J. HOWARD BROWN
the symbols BI(pH 8 - 5) is the sum of the reserve acidity plus
the reserve alkalinity, each value being expressed in terms of
per cent normal acid or ^alkali, i.e., the niunber of cubic centi-
meters of N/1 acid or alkali required to change the hydrogen
ion concentration of 100 cc. of medimn from one stated hydrogen
ion concentration to the other. In figure 1 the reserve acidity
is represented on the abscissa by the distance A to B, the reserve
alkalinity by A to C, and the buffer index by B to C*
The values referred to may be determined by at least three
methods which are as follows. 1. The reserve acidity may
be titrated with alkali from pH n to pH 8.0 and then using the
same sample the buffer index may be titrated with acid from
pH 8.0 to pH 6.0. The reserve alkalinity is calculated by sub-
tracting the former from the latter. 2. The reserve alkalinity
may be titrated with acid from pH n to pH 5.0 and then using
the same sample the buffer index may be titrated with alkali
from pH to 8.0. The reserve acidity is calculated by subtracting
the former from the latter. 3. The reserve acidity may be
titrated with alkali from pH n to pH 8.0 in one sample and the
reserve alkalinity titrated with acid from pH n to pH 5.0 in
another sample, the buffer index then being calculated by addi-
tion of the other two values. Identical results may be obtained
by all three methods if the dilution of the color of the medium
and of the indicator is carefully controlled. Many of the results
here reported were obtained by the first method. However,
the third method is the simplest and is described in detail in
the appendix to this paper. It is hardly necessary to point out
that the titrations may be controlled electrometrically quite as
well as by the colorimetric method, the potentiometer merely
taking the place of the color indicators.
Samples of bouillon from five different laboratories, indicated
by the letters A, B, C, D, and E, have been titrated and the
* Whereas the reserve acidity and reserve alkalinity change with each change
in the reaction of the medium, the buffer index may remain constant.
The prevalent method of titrating media against sodium hydrate with phe-
nolphthalein as an indicator is actually a titration of the reserve acidity to an
end point of about pH 8.5.
HYDROGEN IONS, ETC., OP BACTERIOLOGICAL MEDIA 561
TABLE 1
The buffer index of various bouiUona
BOUIXXON
irniiBSR
Al
A2
A3
A4
A5
A6
A7
A8a
ASb
A8c
A8d
Bl
B2
CI
Dl
D2
El
E2
A9
AlO
All
A12
C2
D3
E3
A13
A14
A15
DSBCBIFTIOII
Plain veal infusion, 1 per cent Fairchild pep-
ton
Plain veal infusion, 1 per cent Fairchild pep-
ton
Plain veal infusion, 1 per cent Fairchild pep-
ton
Plain veal infusion, 1 per cent Fairchild pep-
ton
Plain veal infusion, 1 per cent Fairchild pep-
ton
Plain veal infusion, 1 per cent Fairchild pep-
ton
Plain veal infusion, 1 per cent Fairchild pep-
ton
Plain veal infusion, 1 per cent Fairchild pep-
ton
Plain veal infusion, 0.5 per cent aminoids
Plain veal infusion, 1 per cent Witte pepton
Plain veal infusion, 1 per cent Bacto pepton
Plain beef infusion bouillon
Plain beef infusion bouillon
Plain meat infusion bouillon
Plain meat infusion bouillon
Plain meat infusion bouillon
Plain horse infusion bouillon
Plain veal infusion bouillon
INITIAL
pH
Fermented
Fermented
Fermented
Fermented
Fermented
Fermented
Fermented
veal infusion bouillon
veal infusion bouillon
veal infusion bouillon
veal infusion bouillon
meat infusion bouillon
meat infusion bouillon
beef infusion bouillon
0.3 per cent Liebig extract, 1 .0 per cent Fair-
child pepton
0.3 per cent Liebig extract, 2.0 per cent Fair-
child pepton
0.3 per cent Liebig extract, 1 .0 per cent Witte
pepton
7.2
7.3
7.3
7.4
7.4
7.3
7.3
7.1
7.3
7.2
7.3
7.4
7.6
7.4
6.7
6.8
6.8
6.9
BXTrFXB
INDIX
pH8^
7.3
7.6
7.2
7.7
7.2
6.8
7.3
7.4
7.4
7.1
5.25
4.5
4.0
BSBTB
ACIDXTT
pHn-8
BB-
BBBVB
LiNirr
pH n-5
3.45
3.9
3.85
3.75
3.35
3.5
3.45
5.65
5.95
3.6
3.5
1.7
3.5
3.15
5.6
5.3
5.35
5.0
4.05
3.2
3.5
1.8
2.3
1.25
1.25
0.8
0.75
4.0 0.5 3.5
0.4
0.75
0.8
0.95
0.55
0.6
0.5
0.75
0.2
0.6
1.7
0.7
1.2
1.2
0.75
0.6
1.0
0.15
0.75
1.1
0.5
0.4
0.45
0.35
4.0
3.7
3.25
3.05
3.1*5
3.05
2.8
2.8
2.9
2.95
4.9
5.75
3.0
1.8
1.0
2.3
1.95
4.85
4.7
4.35
4.85
3.3
2.1
3.0
1.4
1.85
0.9
562
J. HOWARD BROWN
TABLE I— Continued
BOUILLON
NUIIBBB
DBflCBIFTIOlf
INITIAL
pH
BurrsB
INDBX
pH8<5
BBBTB
ACIORT
pH tt-8
IIITB
MUX"
Lonrt
pH fr4
A16
A17
A18
A19
C3
0.3 per cent Liebig extract, 1.0 per cent Bacto
pepton
0.3 per cent Liebig extract, 1.0 per cent Fair-
child pepton
0.5 per cent Liebig extract, 1 .0 per cent Fair-
child pepton
0.5 per cent Liebig extract, 2.0 per cent Fair-
child pepton
0.5 per cent Liebig extract, 1.0 per cent Bacto
pepton (contaminated)
7.3
8.1
8.0
8.0
7.7
1.25
2.0
2.6
2.9
4.25
0.3
-0.15
0.0
0.0
0.15
.95
2.15
2.5
2.9
4.1
A20
Bacto bouillon (dehydrated), 0.8 per cent
7.1
0.7
0.25
0.45
The buffer index, reserve acidity and reserve alkalinity are expressed in terms
of per cent normal alkali or acid. Note that the buffer index equals the reserre
acidity plus the reserve alkalinity.
results tabulated in table 1. Each sample represents a different
lot of bouillon. The buffer indices of the samples of plain meat
infusion bouillon varied from 1.7 to 5.95. Samples from our
own laboratory (A), made at different times but under supposedly
uniform conditions, varied from BI 3.45 to 5.25. Of the two
samples from laboratory D one had a buffer index of 1.7 and the
other 3.5. Four lots of bouillon, A8a, A8b, A8c and ASd were
made from the same veal infusion but with different brands
of pepton. Their buffer indices were fairly uniform but not
very high. Somewhat less variation was shown by the samples
of fermented bouillon titrated. Samples of bouillon made
from Liebig's beef extract had low buffer indices except sample
C3 which titrated BI (pH 8 - 5) « 4.25. This sample was
found contaminated by a mixed culture when received. The
lowest index was that of sample A20, made of Bacto Nutrient
Broth (dehydrated) according to the manufacturer's directions
printed on the bottle.
The association of contamination with the high buffer index of
extract bouillon C3 suggested that the growth of the culture
might have altered the buffer index. Two samples of bouillon
HYDROGEN IONS, ETC., OF BACTERIOLOGICAL MEDIA 563
of low buffer index, Bacto bouillon and Liebig extract bouillon,
were inoculated with the mixed culture from bouillon C3, in-
cubated forty-eight hours with sterile controls of the same media,
and the buffer indices titrated. The results, tabulated in table
2, show that in Bacto bouillon the index was doubled and in
extract bouillon was increased slightly. Cultures of Bad. coli
in the same media showed small increases in the indices of both.
A clear centrifugate of the mixed culture in Bacto bouillon had
TABLE 2
The effect of cultures on the buffer index
MXDXUM
Bacto nutrient bouillon
Beef extract bouillon. .
Fermented bouillon.
Plain veal bouillon .
I
{
{
CITUrUBB XNOUBATSD 48 BOUBS
Sterile control
Bact, eoli
Mixed culture from extract bouillon
C3 (clouded whole culture)
Clear centrifugate from the above
Sterile control
Bact. coli
Mixed culture from extract bouillon
C3
Sterile control
Bact. alkcUigenea
Sterile control
Bact. dlkaligenee
FIMAL
PH
7.2
7.3
6.8
6.9
7.4
7.6
7.4
7.6
8.4
7.4
8.1
BUFVBB
IMTDBZ
pH8-fi
0.8
0.0
1.6
1.5
1.55
2.05
1.6
4.25
5.1
4.0
4.2
practically the same buffer index as the clouded culture, showing
that the increase was not due to the presence of bacterial bodies
but to substances in solution. A similar experiment was con-
ducted with Bact. aJkaUgenes using fermented bouillon and
plam unfermented veal infusion bouillon. There was an appre-
ciable increase in the buffer index of the culture in fermented
bouillon but only a slight increase in that of the plain bouillon.
In other experiments the buffer indices of cultures of Bad. coli
in plain veal bouillon increased markedly, but when an excess
of glucose was added little or no change in the buffer index
564
J. HOWARD BROWN
occurred. A hemol}rtic streptococcus produced no change in
the buffer mdex of glucose bouillon though the hydrogen
ion coticentration increased from pH 7.1 to pH 4.7 during incu-
bation for eight days. The results of these experiments sug-
gest that in the cases mentioned the increase in buffer index was
the result of protein metabolism. It is suggested that the ability
or failure of a culture to produce changes in the buffer indices
of media may be of differential value.
TABLE s
Infiuence of the reserve alkalinity and the amount of fermentable eugar on the final
hydrogen ion concentration
monm: tkal iNrxTSioit Bounxoir
OULTURB or BACT. COU
Dextroso
percent
Initial pH
BI
(pH 8-5)
ROH
(pH n-S)
48 houn
pH
96 houn
pH
144 houn
pH
0.5
0.5
0.75
0.75
1.0
1.0
1.25
1.25
•6.2
7.5
6.2
7.5
6.2
7.4
6.1
7.4
4.45
4.1
4.4
4.2
4.3
4.2
4.2
4.4
1.05
3.6
2.0
3.6
1.9
3.5
1.65
3.7
5.1
5.5
5.1
5.2
5.1
5.1
5.1
5.1
5.8
6.5
5.1
5.5
5.0
5.2
5.0
5.1
7.5
7.8
5.4
7.0
4.9
5.3
4.9
51
In figure 1 are plotted the buffer indices of a number of bouil-
lons. The pH values are located along the ordinate axis and
the percentage of normal acid or alkali used on the abscissa.
By the simple methods of titration described above three points
are located, the initial pH at A (as shown on the curve of fermented
bouillon A9), pH 8.0 at B, and pH 5.0 at C. If other points
between A and C are determined they are found to lie very close
to the straight line from A to C. The true form of the curve for
fermented bomllon A9 is shown. A comparison of the curves
shown in figure 1 shows that the smaller the buffer index the
more nearly does the curve approach a straight line.
HYDBOGEN IONS, ETC., OF BACTERIOLOGICAL MEDIA 565
In a certaiii lot of bouillon containing 1 per cent of glucose
BacL coli produced an alkaline reaction after incubation for
four days. This bouillon had a high bu£fer index and reserve
alkalinity. The experiment recorded in table 3 was designed
to explain this phenomenon and shows that the reserve alkalinity
of a medium may be of diagnostic importance. It is seen that
in a bouillon with a reserve alkalinity (pH n - 5) of 3.5 per cent
normal, 1 per cent of glucose was hardly sufficient to insure
continued acidity. The culture in the same medium contain-
ing 0.75 per cent of glucose actually became alkaline to brom
cresol purple (pH 7.0) in one hundred forty-four hours. On
TABLE 4
Acid production by Bacterium coli
IffEDIDM
CHANOSS DUBOro INOUBATXOK
pH
BI
(pH S-«)
8 hours
25 hours
Composition
Tur-
bidity
pH
Turbidity
pH
Titra-
tion to
pH8
Bacto bouillon + 1 per cent
elticose
7.0
6.9
0.7
6.2
5.0
6.1
4-+
4.8
5.5
1.25
Veal bouillon + 1 .per cent
slucose
4.85
The titration is expressed in terms of per cent normal acid or cubic centimeters
of N /20 NaOH required to reduce the acidity of 5 cc. of culture to pH 8.0.
the other hand if the reserve alkalinity was reduced to about
2.0; less than 1 per cent of glucose was sufficient to maintain
the acidity of the culture.
Of what value would the buffer indices illustrated in figure
1 be to the bacteriologist in selecting his medium? To mention
only one or two illustrations; if he were working with a member
of the Bacterium coli group and wished to determine in a few
hours whether the organism would ferment sucrose, he might
select a bouillon with a low buffer index, i.e., one in which the
formation of a small amount of acid would be revealed by a
rapidly rising hydrogen ion concentration. If, on the other
hand, he desired abundant growth and the production of a
566
J. HOWARD BROWN
large amount of acid he would do well to select a medium witii
a high buffer index and high reserve alkalinity. This is illus-
trated in the experiment recorded in table 4, in which Bod. cdi
was grown in glucose bouillons of low and high buffer indices.
The degree of acidity rose much more quickly and the final hydro-
gen ion concentration was higher in the bouillon of low buflFer
index but the amount of acid produced was much greater in the
bouillon of high buffer index. The experiments recorded in
tables 4 and 5 also illustrate the statement of Clark (1915a)
that ''unless the media employed by different laboratories are
identical, at least in their buffer effect, the tltratable acidity
TABLES
Acid production by a streptococcus
KMDVaU
BAXmDSDATS
Compotitton
pH
7.1
6.9
BI
(pH 8-6)
Final
pH
tw&to
pHI.«
Veal bouiUon + 1.0 per cent slucose. Lot 1
3.76
5.2
4.7
4.9
3.9
Veal bouillon + 1.0 per cent Klucose. Lot 2
5.3
The titration is expressed in terms of per cent normal acid or cubic centimeten
of N /20 NaOH required to reduce 5 cc. of culture to pH 8.0.
produced by the same organism may be found to be very dif-
ferent." They also confirm his observation that "the greater
the buffer effect of the medium^ the lower the final hydrogen
ion concentration attained." It may be added, therefore,
that if it is desired to compare the final hydrogen ion con-
centrations or the titratable acidities of similar cultures in
different media, at least the buffer indices of the media should
be known. It is not claimed that the titratable acidity is always
a measure of the amount of acid produced, nor that the buffer
content is the only factor which determines the amount of acid
which may be produced or the amount of growth which a medium
can support. There may be simultaneous production of acid
and alkali by some organisms. It has been shown above that
the buffer content may be altered by the growth of the culture.
HYDROGEN IONS, ETC., OF BACTERIOLOGICAL MEDIA 567
Many organisms grow less abundantly in fermented bouillon
plus glucose than in unf ermented bouillon plus glucose although
the two media have equally high buffer indices. Nevertheless,
the buffer index is one of the most important factors and one
which should be determined.*
CONCLUSIONS
The titration of media is not to be regarded as a crude method
of determining the reaction of media but a process which reveals
facts not disclosed by a simple hydrogen ion determination.
For many common purposes a knowledge of the buffer content
of media is quite as important as the hydrogen ion concentration.
The buffer content between stated limits of hydrogen ion
concentration is easily defined as the buffer index which is the
siun of the reserve acidity and reserve alkalinity between those
limits.
A simple colorimetric method of determining these values is
described, a method which need not consume more than five
minutes time. The determination can be made by any labor-
atory helper who can make a titration or a hydrogen ion deter-
mination and should be recorded for each lot of medium made.
There is appended a copy of instructions for laboratory helpers
and a convenient form of record on which is recorded a sample
titration.
The author wishes to acknowledge his indebtedness to Dr.
P. E. Howe of this department for valuable suggestions and
criticisms.
* Since this paper has been written there has appeared the paper on The Rela-
tion of Hydrogen-ion Concentration to the Growth, Viability, and Fermentative
Activity of Streptococcus hemolyticus by L. F. Foster (Jour. Bact., March, 1921,
6, 161). The author illustrates admirably some of the points brought out in the
present paper. He emphasizes the necessity of knowing the buffer content of a
medium.
568 J, HOWARD BROWN
REFERENCES
Herman, N., and Rsttqeb, L. F. 1918 The influence of carbohydrate on the
nitrogen metabolism of bacteria. Jour. Bact., 5, 389.
BoviB, W. T. 1915 A direct reading potentiometer for measuring and recording
both the actual and total reaction of solutions. Jour. Med. Res., 8S,
295.
Bronfenbrenner, J., AND ScHLBBiNGER, M. J. 1918 Carbohydrate fermen-
tation by bacteria as influenced by the composition of the medium.
Proc. Soc. Exp. Biol, and Med., 16, 44.
Clark, W. M. 1915a The final hydrogen ion concentrations of cultures of
BcunlluB coli. Jour. Biol. Chem., 22, 87.
Clark, W. M. 1915b The reaction of bacteriologic culture media. Jour. Inf.
Dis.,17,109.
Clark, W. M ., and Lubs, H. A. 1917 The colorimetric determination of hydro-
gen ion concentration and its applications in bacteriology. Jour.
Bact., 2, 1.
Conn, H. J., Harding; H. A., Kugler, I. J., Frost, W. D., Prucha, H. J., and
Atkins K. N. 1919 Methods of pure culture study. Progress report
for 1918 of the committee on the descriptive chart of the Society of
American Bacteriologists. Jour. Bact., 4, 128-129.
HuRWiTz, S. H., Meyer, K. F., and Obtbnbbro, Z. 1915 On a colorimetric
method of adjusting bacteriological culture media to any optimum
hydrogen ion concentration. Proc. Soc. Exp. Biol, and Med., 18,24.
Jones, F. S. 1920 Influence of variations of media on acid production by
streptococci. Jour. Exp. Med., 32, 273.
Jones, H. M 1920a Effect of carbohydrate on amino acid utilization of certain
bacteria. Jour. Inf. Dis., 27, 169.
Jones, H. M. 1920b Factors influencing final hydrogen ion concentration in
bacterial cultures with special reference to streptococci. Jour. Inf.
Dis., 26, 160.
Kugler, I. J. 1916 Some regulating factors in bacterial metabolism. Jour.
Bact., 1, 663.
Washburn, E. W. 1910 The significance of the term alkalinity in water analyais
and the determination of alkalinity by means of indicators. Proc.
Second Meeting Illinois Water Supply Assn., p. 93.
Wolf, C. G. L. 1920 The influence of the reaction of media and of the pres^ce
of buffer salts on the metabolism of bacteria. Brit. Jour. Exp. Path.
1,288.
HYDROGEN IONS, ETC., OF BACTERIOLOGICAL MEDIA 569
APPENDIX
METHOD FOB THE TITRATION OF MEDIA
Equipment
A set of colorimetric hydrogen ion standards of the following ranges
and containing the indicators mentioned.
pH 5.0 - 5.8 (methyl red)
pH 5.8 - 6.8 (brom cresol purple)
pH 6.8 - 8.0 (phenol red)
A comparator block.
Drop bottles or pipette bottles containing the indicators mentioned.
Solutions of N/20 NaOH and N/20 HQ.
Two finely graduated burettes.
A very accurate 1 cc. or graduated 2 cc. pipette.
Tubes of uniform internal diameter similar to those containing the
standards. Ordinary potato tubes of NONSOL glass are satisfactory.
Distilled water.
Method
1. Into each of 3 clean tubes place 9 cc. of distilled water and 1 cc.
(very acciu^tely measured) of the medium to be titrated.
2. Make the hydrogen ion determination in the usual manner, using
one of the tubes (tube /) as a color screen and adding phenol red to
another (tube II). (If the hydrogen ion concentration of the medium
lies outside the color range of phenol red but inside the range of brom
cresol purple (pH 5.8 to 6.8) the pH determination had better be made
in a separate sample which is then discarded.)
Record the hydrogen ion concentration on the record sheet,
3. Place the pH 8.0 standard in the comparator block behind the
color screen (tube I). From the burette cautiously add N/20 NaOH
to tube II (containing phenol red) tmtil its hydrogen ion concentration
becomes pH 8.0 as determined by viewing it in the comparator block
beside tube I,
Record figures in spaces a, b, and c of the record sheet,
4. Place the pH 5.0 standard in the comparator block behind tube I.
Discard tube II and to a third tube of the diluted medium (tube III) add
methyl red. From a burette cautiously add N/20 HCl to tube III
until its hydrogen ion concentration becomes pH 5.0.
Record fibres in spaces e, /, and g of the record sheet
570
5. Calculate the r
on the record sheet,
plus the reserve alkal
Record these valuet
Greater accuracy :
containing phenol ret
tration as is present
Meyer and Ostenberi
If sufficient volun
II or HI to change tl
of the contents of th
by the addition of c
indicator.
Determinations sh<
cian has perfect conf
Medium FermerUad Veai
Sample (x) — 1 co. of n
Initial hydrogen ion coi
Titration of reserve acii
Burette ceadbg
Burette reading
Difference
Average
Re
Titration of reserve alk:
Burette reading —
Burette reading
Difference
Average
Real
Calculation of buffer im
Reserve acidity, Ri
Reserve alkalinity,
Buffer indes, BI {p
ON DECREASING THE EXPOSURE NECESSARY FOR
THE GELATIN DETERMINATION
J. E. RUSH AND G. A. PALMER
Sanitary Engineering Department^ Carnegie Institute of Technology, Pittsburgh,
Pennsylvania
Received for publication March 8, 1921
Some time ago, one of us (J. E. R.) was advised of the fact
that there was a more rapid method for determining the ability
of organisms to liquefy gelatin than the routine one, in use in
most laboratories, namely, subjecting the gelatin stab to a tem-
perature of 20'^C. for ten or fourteen days after inoculation and
then noting the results. Search of the literature failed to reveal
any description of the more rapid method which was described
as incubation at ST^'C. for four days followed by twenty-four
hours incubation at 20°C. after which the results were recorded.
Many reasons recommend the latter procedure providing the
results obtained are identical with those recorded by the
present recognized procedure. Among such reasons we might
enumerate :
1. The saving of time (five days requirement as contrasted
with fourteen days) .
2. Earlier liberation of test tubes from the incubator (which
in a busy laboratory is an important factor).
3. Necessity of less incubator space to meet the requirements
of any laboratory (in some cases dispensing altogether with the
use of a 20®C. incubator).
As search of the literature failed to reveal any information
on this point it was determined to test out the two methods
simultaneously on the next set of cultures which came into the
laboratory and upon which confirmatory work (including the
gelatin reaction) was to be done. This opportunity came when
671
JOUBNAL 09 BAOTBUOLOaT, VOL. TI, NO. 0
572 J. £. RUSH AND O. A. PALMER
it was desired to examine several organisms isolated from a
water supply and upon which confirmatory work for Bad. coU
was necessary.
Inoculations of the same batch of gelatin were made in dupli-
cate and controls from the same batch of media were used. In the
making of the media the standard procedure^ was used, i.e.,
10 per cent gelatin was made and the fijial reaction was adjusted
to + 1 on the phenolphthalein scale. As above stated inocular
tions were made in duplicate of the cultures to be examined —
one set was placed in the 20°C. incubator, following the generally
accepted method of procedure and observations were made
after ten and fourteen days (as recorded below). The other
set was placed at 37^0. for four days and then transferred to
the 20**C. incubator for twenty-four hours after which the re-
sults were recorded.
It is a well recognized fact, that in a number of gelatin stabs
exposed to 20^0. the longer the time of exposure, the greater
will be the percentage showing liquefaction. This has been
definitely shown by Gage and Phelps' but so far as we are aware
the relation between a certain time (ten to fourteen da3rs) at
20^C. and the combination incubation, first at 37''C. and later at
20''C. has not been determined. Prolonged high temperature
will keep gelatin from solidifying again but this did not obtain
here with exposure of the gelatin to 37^C. for four days, as evi-
denced by the fact that the controls on the media, while liquid
after removal from the 37*^0. incubator were again solid when
removed from the 20°C. incubator after a further exposure of
twenty-four hours.
This gelatin inoculation is made, as is well recognized, for the
simple purpose of determining the presence or absence of cer-
tain proteolytic enzymes, namely, gelatinases. As in other
biochemical reactions, the rate of reaction is influenced by
certain factors in the environment and one of the most import-
ant factors is that of tempOTature. The cultures experimented
^ Standard Methods for Examination of Water and Sewage, 1920.
* Gage and Phelps. Quoted by Prescott and Winslow. Elements of Water
Bacteriology. John Wiley and Sons. 1915.
EXPOSXTRE FOR GELATIN DETERMINATION
573
with, probably represent an average population of those organ-
isms found in water supplies and giving a positive presumptive
test for Bact. coli, because they are from many sources and
sampled under a variety of conditions.
It should be further recalled that the optimmn temperature
of these organisms, imdoubtedly varied considerably and that
they probably exhibited varying degrees of adaptation. In
addition, it may well be assumed that the difference between
exposure at 37°C. and 20®C. even for a short time would, be
sufficient to stimulate a gelatinase production in certain forms
while inhibiting it in others. That we are probably not dealmg
with a single enzyme which has the power of gelatin liquefac-
tion, and that our problem is thus complicated is evident from
certain work on zymology.'
The general results of our tests are shown in the table below:
UQUBTAOriON AFTXB
KUKCBEB 8TBAINI
Four daya at 37* and one day at 30"
Fourteen days at 20"
None
None
97
None
Slight
78
None
Marked
17
Slight
SUght
8
Marked
Slight
4
Complete
None
1
Complete
Slight
8
Complete
Marked
8
''Slight" signifies 20 per cent liquefaction or less; ''Marked" signifies 25 per
cent liquefaction or more.
CONCLUSIONS
From the table it will be seen that no very definite statements
can be made except that if we desire to get the results (as ordinarily
done now) by exposure to 20°C. for ten or fourteen days — these
same results cannot be realized by exposure to 37*^0. for four
days and then to 20°C. for one day.
* Biochemical Catalysts in Life and Industry. Effront and Prescott. John
Wiley and Sons. 1917.
574 J. £. RUSH AND G. A. VAJMER
It was nttturally noted (as previously reported) that a greater
number of inoculations show liquefaction at 20^C. as time pro-
gresses (comparing results at 20^C. for ten days with those at
the same temperature for fourteen days). It should also be
noted that certain cases show a definite increase in percentage
liquefaction from the ten to the fourteen day period. The
nimiber of tubes which show liquefaction at fourteen days and
none at ten days is however less than one-half of one per cent
of the total cultures examined.
As a general thing more cultures show liquefaction, or there
is an increased amount of liquefaction, at 20^C. for fourteen
days than by the method of exposure to 37® C. for four da3rs and
to 20''C. for one day.
In those inoculations in which a greater Uquefaction by the
more rapid method was noted, it may be pointed out that in
practically every case total liquefaction occurred. Whether
or not this has any significance we are unable to say.
CHART OF THE FAMILIES AND GENERA OF THE
BACTERIA
HAROLD MACY
From the Dairy Bacteriology LahoTotory, University of Minnesota
Received for publication May 19, 1921
The final report^ of the Committee of the Society of Ameri-
can Bacteriologists on Characterization and Classification of
Bacterial Types o£fers a suggestive and tentative outline of
bacterial classification.
The idea of preparing a chart which would illustrate graphi-
cally the position of the orders, families, tribes and genera pre-
sented itself to the writer, with the result that the accompanjdng
chart was prepared. It is realized that the classification is not,
in any way, final but it is thought that the chart may prove
useful to bacteriologists who wish to have a convenient guide
to the arrangement of the Schizomycetes under the proposed
classification.
^ C.-E. A. Winslow, Chainnan, Jean Broadhurst, R. E. Buchanan, Charles
Enunwiede, Jr., L. A. Rogers, and'G. H. Smith. The Families and Genera of the
Bacteria. Jour. Bact., vol. V, no. 3, May, 1920, pp. 191-215.
676
576
HAROLD MACT
SCHIZOMYCETES
INDEX TO VOLUME VI
Anaerobes, On the growth and the proteolytic enzymes of certain 419
, Pathogenic, Studies in, II. Principles concerning the isolation of
anaerobes 446
, Pathogenic, Studies in, IV. Suggestions concerning a rational basis for
the classification of the anaerobic bacteria 521
, Principles concerning the isolation of. Studies in pathogenic anaer-
obes II 445
Anaerobic bacteria, Suggestions concerning a rational basis for the classifi-
cation of the. Studies in pathogenic anaerobes IV 521
Anaerobiosis, Chemical criteria of, with special reference to methylene blue 1
Atkins, K. N., Conn, H. J., Chairman, Kligler, I. J., Norton, J. F., and
Harmon, G. E. Progress report for 1920 conunittee on bacteriological
technic , 135
Azotohficter chroococcum Beij, Studies on 331
BacOli, typhoid, Variations in 275
Bacillus megatherium. The antigens of Corynebacterium dipkiheriae and,
and their relation to toxin. The nature of toxin 103
Bact, dysenteriae, group III, Toxins of 601
Bacteria, anaerobic. Suggestions concerning a rational basis for the classifi-
cation of the. Studies in pathogenic anaerobes IV 521
, Chart of the families and genera of the 575
concerned in the ripening of com silage 45
, The importance of preserving the original types of newly described
species of 133
, Indol production by 471
, nodule, of Leguminosae, Notes on the flagellation of the. 239
Bacteria] cultures. Spiral bodies in \ 371
growth. Salt effects in. I. Preliminary paper 511
system. The main lines of the natural 263
Bacteriological media. Hydrogen ions, titration and the buffer index of 555
Bacteriological technic. Progress report for 1920 committee on 135
Barthel, Chr. Note on the indol test in tryptophane solution 85
Biochemistry, The, of Streptococctta hemolyticus 211
Blanc, J., and Demby, K. G. On the growth and the proteolytic enzymes of
certain anaerobes 419
Bonazzi, Augusto. On Nitrification. IV. The carbon and nitrogen rela-
tions of the nitrite ferment 479
. Studies on Azotohacter Chroococcum Beij 331
Botulism in cattle 69
Broth media, A study of the variations in hydrogen-ion concentration of. . 143
677
578 INBBX
Brown, J. Howard. Hydrogen ions, titration and the buffer index of bac-
teriological media 565
Buffer index of bacteriological media, Hydrogen ions, titration and the 555
Cattle, Botulism in 09
Cause, The, of eyes and characteristic flavor in Emmental or Swiss cheese. . 379
Chart of the families and genera of the bacteria 575
Cheese, The cause of eyes and characteristic flavor in Emmental or Swiss. . 379
Chemical criteria of anaerobiosis with special reference to methylene blue. 1
Classification of the anaerobic bacteria, Suggestions concerning a rational
basis for the. Studies in pathogenic anaerobes IV 521
Colon-aerogenes forms isolated from natural waters, Some atypical 53
Color standards for the colorimetric measurement of H-ion concentration. . 399
Colorimetric measurement of H-ion concentration. Color standards for the. . 399
Conmiittee on bacteriological technic, Progress report for 1020 135
Conn, H. J. Rose bengal as a general bacterial stain 253
, Chairman, Atkins, K. N., Kligler, I. J., Norton, J. F., and Harmon,
G. £. Progress report for 1020 committee on bacteriological technic. . . 135
Council, J. T., and Holly, L. E. The nature of hemolysins 89
, Warden, C. C, and Holly, L. E. The nature of toxin. The antigens
of Corynebaclerium diphiheriae and BaciUua megatherium and their rela-
tion to toxin 103
Corynebacterium diphtheriae and BaciUus megatherium and their relation to
toxin. The antigens of. The nature of toxin 103
Culture media. Solid, with a wide range of hydrogen or hydroxyl ion con-
centration 325
Demby, K. G., and Blanc, J. On the growth and the proteolytic ensymes of
certain anaerobes 419
Effect, The, of pepton upon the production of tetanus toxin 407
Enunental or Swiss cheese. The cause of eyes and characteristic flavor in.. 379
Emsymes, proteolytic. On the growth and the, of certain anaerobes 419
Elyes, The cause of, and characteristic flavor in Emmental or Swiss cheese.. 379
Families and genera of the bacteria. Chart of the 575
Flagellation, Notes on the, of the nodule bacteria of Leguminosae 239
Flavor, The cause of eyes and characteristic, in Emmental or Swiss cheese. . 379
Florence, Laura. Spiral bodies in bacterial cultures 371
Foster, Laurence F. The biochemistry of Streptococcus hemolyticue 211
. The relation of hydrogen -ion concentration to the growth, viability,
and fermentative activity of Streptococcue hemolyticue 161
, and Bimdall, Samuel B. A study of the variations in hydrogen-ion
concentration of broth media 143
Gas production, The, of Streptococcus kefir 127
Gelatin determination, On decreasing the exposure necessary for the 571
INDEX 579
Gillespie, Louis J. Color standards for the colorimetric measurement of
H-ion concentration 399
Graham, Robert, and Schwarze, Herman R. Botulism in cattle 69
Gram stain, A new modification and application of the 395
Growth, bacterial. Salt effects in. I. Preliminary paper 511
, On the, and the proteolytic enzymes of certain anaerobes 419
Guinea-pigs, Method for the intravenous injection of 249
H-ion concentration. Color standards for the colorimetric measurement of. 399
Hall, Ivan C. Chemical criteria of anaerobiosis with special reference to
methylene blue 1
Hamilton, Herbert W. Powdered litmus milk. A product of constant
quality and color whicl^can be made in any laboratory 43
Hammer, B. W., and Plaisance, G. P. The mannitol-producing organisms
in silage 431
Harmon, G. E., Conn, H. J., Chairman, Atkins, K. N., Kligler, I. J., Norton,
J. F. Progress report for 1920 committee on bacteriological technic... . 135
Heineman, P. G., and Hixson, Charles R. Bacteria concerned in the ripen-
ing of com silage 45
Heller, Hilda Hempl. Principles concerning the isolation of anaerobes.
Studies in pathogenic anaerobes II 445
. Suggestions concerning a rational basis for the classification of the
anaerobic bacteria. Studies in pathogenic anaerobes IV 521
Hemolysins, The nature of 89
Hixson, Charles, and Heineman, P. G. Bacteria concerned in the ripening
of com silage 45
Holly, L. E., and Connell, J. T. The nature of hemolysins 89
, Warden, C. C, and Connell, J. T. The nature of toxin. The antigens
of Corynehacterium diphtheriae and Bacilliis megatherium and their
relation to toxin 103
Holm, George E., and Sherman, James M. Salt effects in bacterial growth.
I. Preliminary paper 511
Hucker, G. J. A new modification and application of the Gram stain 395
Hydrogen or hydroxyl ion concentration. Solid culture media with a wide
range of 325
Hydrogen-ion concentration of broth media, A study of the variations in. . 143
concentration. The relation of, to the growth, viability, and fermenta-
tive activity of Streptococcus hemolyticua 555
Hydrogen ions, titration and the buffer index of bacteriological media 161
Importance, The, of preserving the original types of newly described species
of bacteria 133
Indol production by bacteria 471
test, Note on the, in tryptophane solution 85
Intravenous injection of guinea-pigs, Method for the 249
Isolation of anaerobes. Principles concerning the. Studies in pathogenic
anaerobes II 446
\
580 INDEX
Kligler, I. J., Conn, H. J., Chairman, Atkins, K. N., Norton, J. F., and
Harmon, G. E. Progress report for 1020 committee on bacteriological
technic 135
Leguminosae, Notes on the flagellation of the nodule bacteria of 239
Macy, Harold. Chart of the families and genera of the bacteria 575
Main lines, The, of the natural bacterial system 263
Mannitol-producing, The, organisms in silage 431
Method for the intravenous injection of guinea-pigs 249
Methylene blue, Chemical criteria of anaerobiosis with special reference to. . 1
Milk, Powdered litmus. A product of constant quality and color which
can be made in any laboratory 43
Monfort, W. F., and Perry, Margaret C. Some Iftypical colon-aerogenes
forms isolated from natural waters 53
Morishima, Kan-Ichiro. Variations in typhoid bacilli 275
Nature, The, of hemolysins 89
, The, of toxin. The antigens of Corynehacterium diphlheriae and BaciU
Itu megatherium and their relation to toxin 103
New, A, modification and application of the Gram stain 395
Nitrite ferment. On nitrification. IV. The carbon and nitrogen relations
of the 479
Nitrification, On. IV. The carbon and nitrogen relations of the nitrite
ferment 479
Nodule bacteria of Leguminosae, Notes on the flagellation of the 239
Norton, J. F., Conn, H. J., Chairman, Atkins, K. N., IGigler, I. J., and
Harmon, G. E. Progress report for 1020 committee on bacteriological
technic • 135
, and Sawyer, Mary V. Indol production by bacteria 471
Note on the indol test in tryptophane solution 85
Notes on the flagellation of the nodule bacteria of Leguminosae 239
On decreasing the exposure necessary for the gelatin determination 571
nitrification. IV. The carbon and nitrogen relations of the nitrite
ferment. 479
the growth and the proteolytic enzymes of certain anaerobes 419
Organisms, The mannitol-producing, in silage 431
Orla-Jensen, S. The main lines of the natural bacterial system 263
Palmer, G. A., and Rush, J. E. On decreasing the exposure necessary for
the gelatin determination 571
Pathogenic anaerobes, Studies in, II. Principles concerning the isolation
of anaerobes 445
, Studies in, IV. Suggestions concerning a rational basis for the
classification of the anaerobic bacteria 521
Pepton, The effect of, upon the production of tetanus toxin 407
INDEX 581
Perry, Margaret C, and Monfort, W. F. Some atypical colon-aerogenes
forms isolated from natural waters 53
Plaisance, G. P., and Hammer, B. W. The mannitol-producing organisms in
silage 431
Powdered litmus milk. A product of constant quality and color which can
be made in any laboratory 43
Principles concerning the isolation of anaerobes. Studies in pathogenic
anaerobes II 445
Progress report for 1920 committee on bacteriological technic 135
Proteolytic enzymes, On the growth and the, of certain anaerobes 410
Randall, Samuel B., and Foster, Laurence F. A study of the variations in
hydrogen-ion concentration of broth media 143
Relation, The, of hydrogen-ion concentration to the growth, viability and
fermentative activity of Streptococcus hemolyticus 161
Ripening of com silage. Bacteria concerned in the 45
Rose bengal as a general bacterial stain 253
Roth, George B. Method for the intravenous injection of guinea-pigs 240
Rush, J. E., and Palmer, G. A. On decreasing the exposure necessary for the
gelatin determination 571
Salt effects in bacterial growth. I. Preliminary paper 511
Sawyer, Mary V., and Norton, John F. Indol production by bacteria 471
Schwarze, Herman R., and Graham, Robert. Botulism in cattle 60
Sedgwick, William Thompson, 185&-1021 255
Sherman, James M . The cause of eyes and characteristic flavor in Emmental
or Swiss cheese 370
. The gas production of Streptococcus kefir 127
Shunk, Ivan V. Notes on the flagellation of the nodule bacteria of Legumi-
nosae 230
and Wolf, Frederick A. Solid culture media with a wide range of hydro-
gen or hydroxyl ion concentration 325
Silage, com, Bacteria concerned in the ripening of 45
, The mannitol-producing organisms in 431
Solid culture media with a wide range of hydrogen or hydrozyl ion concen-
tration 325
Some atypical colon-aerogenes forms isolated from natural waters 53
Spiral bodies in bacterial cultures , 371
Stain, A new modification and application of the Gram 305
, Rose bengal as a general bacterial 253
Streptococcus hemolyticus, The biochemistry of 211
, The relation of hydrogen-ion concentration to the growth, via-
bility, and fermentative activity of 161
kefir. The gas production of 127
Studies in pathogenic anaerobes II. Principles concerning the isolation
of anaerobes 445
IV. Suggestions concerning a rational basis for the classi-
fication of the anaerobic bacteria 521
582 INDEX
Studied' on AMotdbacter Chroococcum Beij 331
Study, A, of the variations in hydrogen-ion concentration of broth media. . 143
Suggestions concerning a rational basis for the classification of the anaerobic
bacteria. Studies in pathogenic anaerobes IV 521
Swiss cheese, The cause of eyes and characteristic flavor in Emmental or... 379
Tetanus toxin, The e£fect of pepton upon the production of 40(7
Thj0tta, Th. Toxins of Baci. dysenieriaef Group III 501
Titration and the buffer index of bacteriological media, Hydrogen-ions, 555
Toxin, The nature of. The antigens of Corynehacterium diphiheriae and
Bacill7M8 megatherium and their relation to toxin 103
Toxins of Baei. dyeenteriae, Group III 501
Tryptophane solution. Note on the indol test in 85
Typhoid bacilli, Variations in 275
Variations, A study of the, in hydrogen-ion concentration of broth media 143
in typhoid bacilli 275
Warden, C. C, Connell, J. T., and Holly, L. E. The nature of toxin. The
antigens of Corynehacterium diphiheriae and BaciUue megatherium and
their relation to toxin 103
Wilcox, Harriet Leslie. The effect of pepton upon the production of tetanus
toxin 407
William Thompson Sedgwick, 1855-1021 255
Winslow, C.-E. A. The importance of preserving the original ^ypes of newly
described species of bacteria 133
William Thompson Sedgwick, 1856-1921 255
Wolf, Frederick A., and Shunk, I. V. Solid culture media with a^wide range
of hydrogen or hydroxyl ion concentration 325
•
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