TOXINS 67 



Hydrogenase seems to be rather widespread among the yeasts. 

 One hundred and forty years ago, Nessler stated that if flowers of 

 sulfur were added to a liquid undergoing alcoholic fermentation, hy- 

 drogen sulfid would be formed. We shall see further on that accord- 

 ing to Griiss, hydrogenase plays a role in alcoholic fermentations. 



Reductases for other sulfur compounds have been studied by vari- 

 ous investigators. Beijerinck l and Kossowicz and Loew 2 were un- 

 able to find any reduction of sulfates with different strains of yeasts. 

 Among the strains which were used by these investigators, were Sac- 

 charomyces cerevisiae and Saccharomyces ellipsoideus. Tanner, 3 how- 

 ever, demonstrated sulfate reduction with 9 out of 30 pure cultures 

 of yeasts. The fungi, used by Tanner, could also split hydrogen 

 sulfur from other sulfur compounds. Most of the cultures could 

 attack the sulfur in sodium thiosulfate and a few reduced the sulfur 

 in sodium sulfite. Free sulfur was also changed to hydrogen sulfide. 



Oxydases are enzymes which oxidize and yield peroxides. Grtiss 

 has pointed out the presence in yeast of an oxidase which does not 

 act on guaiac but gives a violet reaction with tetramethylphenylen- 

 diamine. This enzyme oxidized aldehydes to acetic acid and reduced 

 fuchsin and methylene blue. 



It is undoubtedly due to this enzyme that certain yeasts are able 

 to oxidize alcohol in contact with air. Grtiss believes that they play 

 a large role in respiration. 



Toxins 



Haydruck was the first to point out the existence in yeasts of an 

 endotoxin capable of killing them when it is extracted from the cells 

 and introduced into the culture media. Fernbach 4 and Vulquin 6 have 

 confirmed the existence of this toxin which seems to play toward the 

 yeast the role of an antiseptic. These authors have prepared this 

 substance in the following manner: Compressed yeast, previously 

 dried at 70, is macerated in a 1 per cent solution of hydrochloric 

 acid for about 20 hours at 35-37. The filtered macerated mixture 

 is evaporated under reduced pressure, having been slightly alka- 



1 Beijerinck, M. W. Cent. Bakt. Parasitenk. Abt. II, 6, 194-206, 1900. 



2 Kossowicz and Loew. Garungsphysiol. 2, 87-103 (1912). 



3 Tanner, F. W. Studies on the Bacterial Metabolism of Sulfur. II. For- 

 mation of hydrogen sulfid from certain sulfur compounds by yeast-like fungi. Jour. 

 Amer. Chem. Soc. 60 (1918), 663-9. 



4 Fernbach, A. Sur un poison elabore par la levure. Comp. Rend. Acad. 

 Sci. 144, 1909. 



6 Fernbach, A., and Vulquin, E. Quelques observations nouvelles sur le 

 pouvoir bacte"ricide des macerations de levures. Comp. Rend. Acad. Sci. 67, 1909. 



