240 UTILIZATION OF CARBOHYDRATES 



produced by some few microbes. Voges and Proskauer' described a color reaction 

 that could be elicited in glucose cultures of certain bacteria by the addition of enough 

 caustic potash solution to render the reaction of the medium very alkaline. Ordinari- 

 ly, the color develops slowly in fermentation media, requiring from twenty-four to 

 forty-eight hours to reach its maximum. The color thus evolved was reminiscent of 

 the yellowish fluorescence exhibited by alcoholic solutions of eosin. 



Harden and Walpole' studied the reaction chemically and found acetylmethyl- 

 carbinol (CHjCO- CHOH- CH,) was present in such media. They discovered, further- 

 more, that this compound would not give the color with caustic potash, but that when 

 the oxidization product of acetylmethylcarbinol. diacetyl (CH3'CO-CO'CH3) was 

 obtained it reacted with some unknown constituent of peptone in the presence of 

 caustic potash and gave the color very quickly and intensely. The steps involved 

 seem to be: 



1 .C6H,.Oo->CH3 . CO • CHOH • CH3 , 



(Glucose) (Acetylmethylcarbinol) 



2 .CH3 • CO • CHOH • CH3-^CH3 • CO • CO • CH3 , 



(Diacetyl) 



3.CH3 • CO • CO • CH3+Peptone+KOH->Voges-Proskauer reaction . 



Grimbert^ found that certain spore-forming bacteria, as Bacillus suhtilis and 

 Bacillus meseiitericus , gave this Voges-Proskauer reaction, and MacConkey^ added 

 Bacillus lactis aerogenes, Bacillus cloacae, and certain members of the Bacillus 7nucosus 

 capsulatus group to the list. Most strains of Bacillus coll do not give it.^ 



The reaction seems to be elicited quite definitely in cultures of certain bacteria 



which give a negative methyl-red reaction^ (low H-ion concentration) and a gas ratio 



(^O, 2 — ^ 



of -^ = . This includes the lactis aerogenes and mucosus capsulatus groups of 



H2 I 



bacteria in addition to Bacillus cloacae.'' 



Miscellaneous fermentations. — A considerable number of fermentations induced 

 by bacteria that have significance in the industries and agriculture have been report- 

 ed. Some of these, as the organisms which produce mannitol, together with lactic 

 and acetic acids, and carbon dioxide from fructose* are important not only from the 

 viewpoint of their relation to the wine, sauerkraut, and other similar industries, but 

 also because they provide a starting-point for the study of biologically induced 



' Voges, O., and Proskauer, B.: Ztschr.f. Ilyg. 11. Infektionskranhh., 28, 20. 1898. 



= Harden, A., and Walpole, S. G.: Proc. Roy. Soc. (Ser. B), 77, sqq. 1906; Harden, A.: ibid., 

 p. 424. 1906. 



J Grimbert, L.: Compt. rend. Soc. de hiol., 53, 304. 1901. 



■•MacConkey, A.: J. Hyg., 5, 349. 1905. 



sLevine, M.: Official Publication, Iowa Slate College Agrinilt. &" Afecli. Arts, 15, No. 14. 1916. 



'Rogers, L. A., Clark, W. M., and Evans, A. C: /. Infect. Dis., 15, 100. 1914; 17, 137. 1915; 

 Perkins, R.: ibid., 37, 232. 1925; Paine, F. S.: J. Bad., 13, 269. 1927. 



' MacConkey, A.: loc. cit. 



8 See Stiles, H. R., Peterson, W. H., and Fred, F. B.: /. Biol. Cliem., 64, 643. 1925. 



