fact, - jb.asm.org · tried oospora lactis would have been considered incapable of b synthesis....

SYNTHESIS OF VITAMIN B BY MICROORGANISMS

GERTRUDE SUNDERLIN AND C. H. WERKMANBacteriology Section, Iowa Agricultural Experiment Station, Ames, Iowa

Received for publication, January 7, 1928

Studies on the synthesis of vitamins have led to no generalagreement as to the ability of specific micro6rganisms to producevitamin B or as to the extent of this synthesis among the lowerplant forms.

This lack of agreement may be attributed in part to the failureof investigators to keep clearly in mind the characteristics andproperties that define a vitamin and in part to the marked differ-ences in methods which have been employed.There is, on the one hand, the group which has adhered rigidly

to the conception of a vitamin as defined by Drummond (1924),i.e., a substance of unknown constitution neither fat, protein,carbohydrate, nor mineral salt, necessary for the life and well-being of a suitable organism. On the other hand, there is agroup which has disregarded the requirements of Drummond andhas used as the criterion of the presence of vitamin B, the abilityof a substance to stimulate multiplication of a specific micro-organism. The yeast growth test of Williams (1919) employsthe multiplication of Saccharomyces cerevisiae.

If we exclude from analysis results which are not in strict con-formity with the definition of Drummond, we are still confrontedby the use of a multiplicity of methods all purporting to detectthe presence of vitamin B. The animal used may have been therat, mouse or pigeon. In certain cases a few milligrams haveconstituted the entire quantity of microorganisms fed per rat perday and the ability of an organism to synthesize vitamin B hasbeen decided upon the results obtained in such experiments.Again, the period of feeding has varied from two to several

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18 GERTRUDE SUNDERLIN AND C. H. WERKMAN

weeks. Generally, no cognizance has been taken of the mannerof feeding, or the time required by the animals to become accus-tomed to the taste of the micro6rganisms. In feeding certainmicro6rganisms, the animals may continue to lose weight for aslong as a week. In certain cases the organisms have been fedapart from the basal ration, whereas, in other cases they havebeen intimately mixed with the constituents of the basal ration.

Again, too little attention has been given to the freedom of theculture medium from vitamin. At the most, it should not con-tain more than traces of vitamin. Vitamin-free synthetic mediaare to be preferred.For the purpose of this investigation Drummond's definition

of a vitamin is accepted; no other conception is justifiable in thelight of present knowledge and no adequate proof has beenoffered that vitamin B, as defined by Drummond, has anyeffect on the rate of multiplication of micro6rganisms. In fact,Werkman (1927) has shown by an analysis of experimental data onmultiplication of Azotobacter chroococcum and Rhizobium legu-minosarum that vitamin B does not stimulate multiplication ofthese organisms.The purpose of this investigation was (1) to determine whether

vitamin B is synthesized by certain bacteria, one torula and formsintermediate between molds and bacteria, (2) to choose theseorganisms from biologically separate groups of the lower plantforms so as to give an indication of the general occurrence ofvitamin B synthesis among microorganisms, (3) to determinerthe variation, if any, in the ability of different strains of the samespecies to synthesize the B vitamin, (4) to make a quantitativestudy of the production of the vitamin, (5) to determine theeffect of drying of the organisms on their vitamin content.

Feeding the microorganisms in testing for the vitamin has beenquantitative so far as practicable. As much as 15 grams oforganisms per rat per day have been fed. Care has been takento accustom the rats to the diet and experiments have been con-tinued until definite results were secured. The culture mediahave been synthetic or thoroughly extracted with 95 per centhot alcohol to insure suitability for use. The uninoculatedmedium was always fed to control animals.


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LITERATURE

Among the workers using rats in determining the presence ofvitamin B, were Wollman (1921) and Wollman and Vagliano(1922) who tested the Bulgarian bacillus and Amylomucor Bfor vitamins A and B. They concluded that neither vitamin Anor B was present. Slanetz (1923) using mice found that Azoto-bacter chroococcum, Bacterium lactis-acidi, Bacillus mycoides,Serratia marcescens, Rhizobium leguminosarum, Bacillus subtilisMicrococcus agilis and three other soil forms produced neitherA nor B.Cunningham (1924) fed young rats in order to test for both A

and B in three strains of the tubercle bacillus. She found neither.Pacini and Russel (1918) in some work referred to by McCollum

and Simmonds (1925) as "not convincing" claim to have shownstimulation of the growth of rats by extracts of typhoid bacilli.Bierry and Portier (1918) injected under the skin and into theperitoneal cavity living cultures of some normal intestinal bac-teria. Their animals showed improvement within twenty-fourto forty-eight hours.Damon (1921) has probably tested more organisms for vitamin

B synthesis than any other worker who has published. Hisfirst results with para B, Bacterium coli and Bacillus subtilis werenegative. In a later publication (1923) he concluded thatPfeiffer's bacillus and the timothy bacillus synthesized vitamin Bbut that Bacillus adhaerens and Friedlander's pneumobacilluswere negative. Damon (1924) believed that a substance analo-gous to vitamin B was produced by Mycobacterium smegmatis,Mycobact. phlei and Mycobact. moelleri. Hunter (1923) con-cluded that Azotobacter synthesized vitamin B. Kuroya andHosoya (1923) concluded that Bacterium coli was capable ofsynthesizing B. Hoet, Leclef and Delarue (1924) using both ratsand pigeons found Torula rosea, and Mycoderma cerevisiae nega-tive but Monilia candida positive.

Funk's pigeon test has been used extensively to determine thepresence of vitamin B. McCollum and Simmonds (1925) gaveevidence to support the view that "the pigeon test as ordinarily

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carried out is without value for the specific purpose for whichit has been so widely used."Cooper (1914) fed Bacterium coli to pigeons on a polished rice

diet but found no evidence of vitamin B. Weill, Arloing andDufourt (1922) fed the colon bacillus and three spore formersfrom the intestinal tract of pigeons to pigeons on a polished ricediet. The birds died in wbat was considered normal time forpolyneuritic pigeons.

Scheunert and Schieblich (1922, 1923) fed cultures of variousbacteria to pigeons. They concluded that there was some effectdue to vitamins in certain bacteria and no effect with otherorgams Eijkman, Van Hoogenhuije and Derks (1922) con-cluded from their experiments that Bacterium coli contains noantineuritic factor. They used pigeons in their work.

William's test for vitamin B depends upon the assumptionthat the increased multiplication of yeast cells upon the additionof alcoholic extracts of various substances is a measure of water-soluble B and that only. Souza and McCollum (1920) andFulmer, Nelson and Sherwood (1921) have presented evidence tothe effect that the yeast growth test is unreliable.Robertson (1924) using William's yeast growth test concluded

that Bacterium coli, Serratia marcescens, Bact. proteus, Pseudo-monas pyocyanea, Bacillus subtilis and Sarcina lutea synthesizeda vitamn.Thjotta (1921) obtained evidence of a growth promoting sub-

stance for the influenza bacillus from Bacillus proteus, Bacillusozaenae and Friedlander's pneuxnobacillus. Damon (1921), how-ever, did not confirm these results.

METHODS AND MATERAL

The authors have felt that the only adequate test for the pre&-ence of vtamin B is the effect of a substance upon the growth ofyoung 50-gram white rats. Weighings of the rats receiving thesubstance to be tested, of control rats receiving the B deficientration, and of rats receiving the basal ration made complete bythe addition of 5 per cent wheat embryo or yeast, were made andgrowth curves over a period of several weeks compared. Metal


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cages with a small quantity of shavings were used. The cageswere cleaned weekly.The basal ration consisted of alcohol extracted casein 18 parts,

corn starch or dextrin, 73.3 parts, salt mixture 3.7 parts, salt-free butter fat 5 parts. The salt mixture was that of McCollumand Davis (1915) modified by the addition of 0.002 gram of KIand the substitution of ferric citrate for the lactate. The caseinwas continuously extracted with hot 95 per cent alcohol forseventy-two hours.Young 45- to 50-gram rats were kept on this ration until

definite symptoms of vitamin deficiency were observed beforefeeding of the organisms was started.The microorganisms were generally fed moist in a separate

container; at other times, they were mixed with the basal rationas indicated in the individual experiment. The organisms weregenerally grown on media in 18- by 40-inch pans. The mediaused are indicated under the experimental results with eachorganis. They were synthetic where practicable. Where pep-tone or agar was used, each had been continuously extracted withhot 95 per cent alcohol for never less than one week. The mediawere always fed to control animals as a check.

EXPERIMENTAL RESULTS

Torula roseaTorula rosea from the stock culture collection of the department

was grown on medium E of Nelson, Fulmer and Cessna (1921),modified by the use of alcohol extracted agar and sucrose. Sur-face growth from the pans was scraped off after three days andfed moist. In the feeding of Torula rosea mixed with the basalration, it was found that the rats consistently refused to eatappreciably of the mixture.When the torula was fed separately, the rats are it readily.

This may account for the fact that Torula rosea is reported in theliterature as not synthesizing vitamin B. By actual determina-tion it was found when the torula was mixed in the basal ration,

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22 GERTRUDE BUNDERLIN AND C. H. WER

the rats received approximately 2 grams per rat per week, anamount too small to supply the vitamin need of the animal.

In figure 2 the animals received the mixed ration from thethird until the end of the fifth week. Beginning with the sixth

20 2 4 6 8 /0 WseereControls

accho'omyce ce'evsioe addedat t _- __Wheat embryo ododed at tVitamin B. free raion.

FiG. 1. EFFJECT OF Saccharomyces cerer?8iae UPON THE GROWTH OF VITAMiN BDEFICIENT RATS

Organism feeding started at

week the torula was fed separately at the rate of 8 grams perrat per day. One animal was in a moribund condition and died.The remaining two began to gain in weight immediately. Again of approximately a gram per rat per day body weight isrecorded for each day torula was fed apart from the basal ration.


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SYNTHESIS OF VITAMIN B BY MICRO6ORGANISMS 2

Oospora lactisNo record of the synthesis of vitamin B by O5spora lactis has

been found. We have found it a rich source of the vitamin.The organism was grown on a synthetic medium:

gramaK2HPO4........................................................ 2.0(NH4)2S04.2.0Succinic acid................. ... 0.5Ca12.0.1FeCl.0.1MgSO.0.2Glucose (extracted).15.0Distilled water................................................1000.0

0a 2 4 6 we'

rQU/ osecoFIG. 2. EFFECT OF Torula rosea UPON THE GROWTH OF VITAMIN B

DEFICIENT RATSOrganism feeding started at 'j

This medium gave a heavy pellicle growth within four days,which could be removed en masse. Quantitative feedingexperiments were made with this organism to determine therequirements of rats. One of several experiments is given infigure 3. The organism was fed at the rate of 2.5 grams per ratper day during the sixth week. It was then fed ad libitum duringthe seventh week when the rats consumed approximately fifteengrams per rat per day. During the eighth week it was again fedinlamounts of 2.5 grams and ad libitum during the ninth and

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24 GERTRUDE BUNDERLIN AD C. H. WE

tenth weeks. When fed at the rate of 2.5 grams per rat per daythe animals made no gain and if larger quantities had not beentried Oospora lactis would have been considered incapable ofB synthesis. Larger quantities fed to the same animals gaveexcellent gains. Oospora lactis is a good source of vitamin B,distinctly better than Torula rosea.

'70

VW

z 4 6 8 /O wh:8Oospor ladeis

FIG. 3. ErFcrT oF O6pora lacti8 UPON TE GROWTH Or VITAMN BDEFICIENT RATS

Organism feeding started at IBacillus adhaeren

Bacillus adhaerens was chosen primarily because we weredesirous of employing in certain experimental work an organismincapable of synthesizing vitamin B and this one had been soreported in the literature.The organism was grown on extracted peptone agar in large

petri dishes. The composition of the medium was:

Alcohol extracted peptone.......................... .............7.0Alcohol extracted agar.......................................... 15.0K,HPO4........................................ .......... 2.0Distilled water ................................................. 1000.0


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The growth was scraped from the medium after forty-eighthours incubation and fed separately. Three grams per rat perday were given to the rats in the experiment shown in figure 5.In this particular experiment after feeding the organisms for twoweeks they were omitted from the ration. A drop from 16 to2.6 grams occurred in the average gain per rat per week. Ba-cillus adhaerens is an excellent synthesizer of vitamin B.

/20

/00

60

4J/0 4 6w_e__s/60 Actinornyces

Fla. 4. EFFECT OF Actinomyces UPON THE GROWTH OF VITMIN B DEFICIENT RATSOrganism feeding started at I

Bacterium coli

Three strains of Bacterium coli were tested in this experimentto determine the relative potencies of the different strains.Four grams per rat per day were fed separately. The resultsdemonstrated that Bacterium coli is capable of synthesizingvitamin B and that no significant differences exist in the abilityof the different strains to perform the synthesis. A growth

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26 GERTRUDE StNDERLIN AND C. H. WER

curve showing the average increase in weight of three rats fedstrain no. 24 is shown in figure 5.

Bacillus subtilisThe organism was grown on extracted peptone agar, scraped

off and fed apart from the basal ration. In the experimentgraphed in figure 5 the rats received 6 grams per rat per dayuntil the eighth week when they received 1 gram per rat per day.

.~~~~~~~~~90 A

Bacillus -subtilisBacterlum col; -Bocillus odhaerens

Fio.5. EFFECToF BACTERIA UPONTHE. GROWTH o VITANaN B DEmcxzNTRATs

Organism feeding started at ~

In order to demonstrate that the marked loss of weight result-ing was due to insufficient vitamin, the rats were again fed 6grams per rat per day during the ninth week. Although Ba-cillus subtilis serves as an excelent source of vitamin B, one gramper rat per day of the micro6rganism is insufficient to maintbody weight.Drying the bacterial growth at 37°C. for two days had no

detectable effect on the vitamin potency.


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SYNTHESIS OF VITAMIN B BY MICROORGANISMS 27

Bacillus mycoidesQuantitative feeding results with Bacillus mycoides are given

to demonstrate the effects of feeding various amounts of an

/60 1

o /,~~~~140

t~~~~~~ooo /'~~~/:0

600

.4(/, /

eo~~~~~~~

4°% ~ X 4 6 8 weers

Azo6obbocer chroococcumRhl'zobium /eyum/nosorY//n

FxI. 6. EFFECT OF BACTERIA UPON THE GROWTH OF VITAMIN B DEFICIENT RATS

Organism feeding started at 4

organism. It is apparent that if 2 grams or less per rat per dayof mycoides were fed, the conclusion might be drawn that theorganism is unable to synthesize vitamin B, whereas, our results


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28 GERTRUDE SUNDERLIN AND C. H. WER1N

demonstrate that mycoides is a good source of vitamin B whencompared with other organisms. In the results of the experimentgiven in figure 7, groups of rats were fed simultaneously 0.5,1.0, 2.0, 4.0 and 8.0 grams of B. mycoides per rat per day. The

C B.rnycol.es feedmn eladi80 8

70

60

40 i 2 3 4 5r weeks

NeAoi9ve contro/--no oqonism ..........

0.5 9m". amycol'es pera rot perdo/_g mn. .rnycos:des pernatper "y_

2 mns. 8.&nc0;dGs per rot peraby .4 9mn. B.ivycoides per rot per coy9ms. 5a myco'des per rot perdady

FIG. 7. GROWTH OF THE WHITE RAT ON VITAIN B DEFICIENT RATION ANDVARYING AMOUNTS OF BACILLUS MYCOIDES

group receiving 0.5 gram per rat per day lost weight just slightlyless rapidly than the rats receiving no organisms; while the groupreceiving 1.0 gram per rat per day in two week's time averaged aslight loss of weight. The groups receiving 2.0, 4.0 and 8.0grams gained in order of increasing quantity fed.


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During the third week of the feeding of the organism (fig. 8)the rats that had been receiving 8.0 grams were given 2.0 gramsand vice versa. The rats that had received 2.0 grams per ratper day had made an average gain of 2 grams per rat per week.

qo

l

80A

o

60

40 , 2 3 4 5 6 Weems

Negoaive confrol- no olyoni3msZ9s. B.mycokdes per rotpendaydo49oms. .fi rnycoiSes per rot per,do8grms. amycoides per rot per ay _ ____

FIG. 8. GROWTH OF THE WHITE RAT ON VITAMIN B DEFICIENT RATION AND2 GRAms B. MYCOIDES INTERCHANGED WITH 8 GRAMS

When fed 8.0 grams per rat per day they made an average gainof 24 grams in one week. This marked increase can be accountedfor only as due to the increase in the amount of the organism fed.The rats that had been given 8.0 grams per rat per day made

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an average gain for the two weeks of 12 grams per week. Whenreduced to 2.0 grams the average gain per week was 7 grams.

Organisms dried at 370C. and at 10000. for forty-eight hourswere fed in order to determine the effect of desiccation on thevitamin potency. The results indicated no effect of drying at37°C. and only a slight effect at 1000C.

Azotobacter chroococcum

This organism was grown on Ashby's medium modified bythe use of alcohol extracted sucrose. The animals ate readilyof the bacterial growth when mixed with the basal ration orwhen fed separately. In figure 6 are shown the results of feeding6 grams per rat per day separately. Two grams per rat perday were found to be inadequate to provide sufficient vitamin Bfor increase in body weight.

Rhizobium leguminosarumRhizobium was grown on Ashby's medium modified as for

Azotobacter. The strain happened to be one isolated from alfalfaroots. Synthesis of vitamin B by this organism is indicated bythe growth curve in figure 6.

Actinomyces (species unknoyn)An unknown soil actinomyces was grown on the following

medium:grams

K2HPO4.... 1.0KNOs ........ ................................................. 2.0Calcium succinate............ 10.0Extracted agar............ 17.0NH4Cl............................. 1.SDistilled water......... 1000.0

Considerable difficulty was experienced in obtaining sufficientgrowth to feed. Long periods of incubation were necessary sothat the growths scraped from large plate cultures were stored forseveral days before the experiment began in order to have suffi-cient growth to complete the feeding. Six grams per rat per day


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to 2 rats constituted the only work done with actinomyces.The growth curve is shown in figure 4. The results indicate avitamin B synthesis by the organism.

SUMMARY AND CONCLUSIONS

The synthesis of vitamin B by such biologically separatedgenera of micro6rganisms as Torula, O6spora, Actinomyces andfour genera of the order Eubacteriales reveals a general occur-rence of vitamin B synthesis among widely separated groups ofthe lower plant forms. Vitamin B, whatever its structurechemically may be, is a constituent prevalent in microorganisms.

Specifically the following organisms were found to produce thegrowth promoting vitamin for white rats: Torula rosea, Oosporalactis, Bacillus adhaerens, Bacterium coli, Bacillus subtilis, Bacillusmycoides, Azotobacter chroococcum, Rhizobium leguminosarum andActinomyces (species unknown).The results showed no marked differences in the ability of

three strains of Bacterium coli to synthesize vitamin B.Drying at 37°C. or at 100°C. for forty-eight hours does not

materially diminish the vitamin potency of the bacterial mass.Several reasons are suggested to account for the discrepancies

present in the literature dealing with the synthesis of vitamin Bby micro6rganisms. Our conceptions of a vitamin are not inaccord and thus differently defined the term vitamin assumes anambiguous and obscured meaning until it is in direct conflictwith the original conception intended.

After limiting by definition the meaning of the term vitaminto the legitimate conception expressed by Drummond we find amultiplicity of methods employed to determine the synthesis of avitamin by micro6rganisms. Important among these are (1)quantity of organism fed, (2) period of feeding and time allowedfor the rats to become accustomed to the bacterial diet, (3)manner of feeding organisms to the rats, (4) species of animal usedas an indicator.

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32 GERTRUDE SUNDERLIN AND C. B. WERKMAN

REFERENCES

BIERRY, HENRI, ET PORTIER, PAUL 1918 Vitamines et symbiotes. Compt..

Rend. Hebdom. d. seanc. de l'acad. d. scienc., 166, 963.COOPER, E. A. 1914 On the protective and curative properties of certain food

stuffs against polyneuritis induced in birds by a diet of polished rice.Jour. Hyg., 14, 12.

CUNNINGHAM, RUBY L. 1924 An attempt to determine the presence of vitaminA and B in tubercle bacilli. Amer. Rev. Tuberc., 9, 487.

DAMON, SAMUEL R. 1921 Bacteria as a source of water soluble B vitamin.Jour. Biol. Chem., 48. 379.

DAMON, SAMUEL R. 1923 Observations on the growth of the influenza baoillus.Amer. Jour. Eyg., 3, 247.

DAMON, SAMUEL R. 1923 Some observations in regard to growth-promotigsubstances of bacterial origin. Jour. Biol. Chem., 56, 895.

DAMoN, SAMUEL R. 1924 Acid-fast bacteria as a source of vitamin B. Jour.Path. and Bact., 27,163.

DRUMMOND, J. C. 1924 Some modern tendencies of vitamin research. Chem.and Ind., 43, 908.

EI KMAN, C. C., VAN HOEHIJzE, J. C., AND DERKS, T. J. G. 1922 Thevitamin content of microorganisms in relation to the composition ofculture medium. The vitamin content of yeast. Jour. Biol. Chem.,50, 311.

FULMER, ELLIS I., NELSON, VICTOR E., AND SHERWOOD, F. F. 1921 The nutri-tional requirements of yeast. I. The r6le of vitamins in the growthof yeast. Jour. Amer. Chem. Soc., 43, 186.

HOET, J., LECLEF, G., AND DELARUE, G. 1924 Recherches sur la synthese desvitamines B par les microorganismes. Arch. intern. physiol., 23, 284.

HUNTER, 0. W. 1923 Production of a growth-promoting substance by Azoto-bacter. Jour. Agr. Research, 23, 825.

KUROYA, DR. MASAHIKO, AND HOSOYA, DR. SEIGO 1923 The synthesis of water-soluble vitamin by coli bacillus grown on synthetic medium. Scien-tific reports from the Government Institute for Infectious Diseases,Tokyo Imperial Univ., 2, 287.

MCCOLLUM, E. V., AND DAVIS, MARGUIERITE 1915 Nutrition with purified foodsubstances. Jour. Biol. Chem., 20, 641.

MCCOLLUM AND SIMMONDS 1925 The Newer Knowledge of Nutritibn. TheMacmillan Company.

NELSON, V. E., FULMER, ELLIS I., AND CESSNA, RUTH 1921 The nutritionalrequirements of yeast. III. The synthesis of water-soluble B byyeast. Jour. Biol. Chem., 46, 77.

PACINI, AUGUST J. P., AND RUSSEL, DOROTHY WRIGHT 1918 The presence of agrowth-producing substance in cultures of typhoid bacilli. Jour.Biol. Chem., 34, 43.

ROBERTSON, R. C. 1924 Food accessory factors (vitamins) in bacterial'growth.VIII. Relations of substances formed by B. coli to the growth ofyeast. Jour. Infect. Dis., 34, 395.


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SYNTHESIS OF VITAMIN B BY MICROORGANISMS 33

ROBERTSON, R. C. 1924 Food accessory factors (vitamins) in bacterial growth.IX. Growth of several common bacteria in a synthetic medium andrelation of substances formed by them to the growth of yeast. Jour.Infect. Dis., 35,311.

SCHEUNERT, ARTHUR, AND SCHIEBLICH, MARTIN 1922 Studien uber die Magen-darmflora polyneuritischer Tauben und die Bildung antineuritischenVitamins durch Darmbakterian. Centralblatt. Bakt., I, Orig., 88,290.

SCHEUNERT, ARTHUR, AND SCHIEBLICH, MARTIN 1923 Zur Kenntnis der Vita-mine, II Mitteilung. Uber die Bildung von Vitamine B durch obligateDarmbakterian. Biochem. Zeitschrift., 57, 139.

SLANETZ, E. J. 1923 Bacteria as a source of vitamins. Proceedings of theConnecticut Branch. Soc. Amer. Bact. Abs. Bact., 7, 352.

SOUZA, GERALDO DE PAULA AND McCOOLLUM, E. V. 1920 A study of the factorswhich interfere with the use of yeast as a test organism for the anti-neuritic substances. Jour. Biol. Chem., 44, 113.

THJOTTA, THEODOR 1921 Studies on bacterial nutrition. I. Growth of Bac-illus influenzae in hemaglobin-free media. Jour. Exper. Med., 33,763.

WEILL, E., ARLOING, F., ET DUFOURT, A. 1922 Essai de traitement de la carencedu pigeon par des cultures mortes on vivantes de microbes intestinaux.Compt. rend. Soc. de Biol., 87, 50.

WERKMAN, C. H. 1927 Vitamin effects in the physiology of microorganisms.J. Bact., 14, 335.

WILLIAMS, ROGER J. 1919 The vitamin requirement of yeast. A simplebiological test for vitamin. Jour. Biol. Chem., 38; 465.

WOLLMAN, E. 1921 Sur le role des microorganisms dans la production desvitamines. Compt. rend. Soc. de Biol., 85, 801.

WOLLMAN, E., ET VAGLIANA, M. 1922 Sur le role des microorganismes dans laproduction des vitamines. Recherches sur la production des vitaminesde croissance par la Bacille bulgare et l'amylomucor B. Compt. rend.Soc. de Biol., 86, 832.


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