ALCOHOLIC FERMENTATION 385 



bodies have been identified in other Fungi, such as Mucor 

 stolonifera * and Aspergillus niger.^ 



OTHER ENZYMIC ACTIVITIES OF SACCHAROMYCES. 



In addition to zymase, other enzymes are associated with 

 yeast, e.g. diastase, invertase, trypsin, protease, emulsin, and 

 peroxidase. 



For laboratory purposes the fermentative activity of Sac- 

 charomyces may be quickly and conveniently illustrated by 

 the use of Pasteur's solution, the composition of which is as 

 follows : 



Ammonium tartrate, 50 grams 

 Potassium phosphate, 10 grams 

 Calcium phosphate, i gram 

 Magnesium sulphate, i gram 



These salts are thoroughly ground and mixed in a mortar, and 

 i gram of the mixture together with 12 grams of glucose are 

 dissolved in 70 c.c. of water, the yeast being added to the 

 solution. 



If cane sugar be used, marked fermentation will only 

 begin after an interval of time has elapsed, during which the 

 Invertase secreted by the yeast converts the sucrose, which is 

 not directly fermentable by yeast, into invert sugar. 



But, according to Bokorny,t sucrose is better than glucose, 

 and urea is better than ammonia in the culture solution. 

 Access of air is important, but the presence or absence of 

 light does not much matter. 



Yeast, or yeast-juice, can set up fermentation in other sub- 

 stances besides glucose, such, for example, as galactose, 

 mannose, fructose,!! sodium lactate,1T and, according to Neu- 

 berg and Tir,** common plant acids, fatty acids, glycerol, and 

 lecithin. 



* Kostytschew : " Ber. deut. hot Gesells.," 1904, 22, 207. 



fMaximow : id., 1904, 22, 225. 



JBokorny : " Allg. Brau. Hopfen. Zeitsch.," 1917, 57, 447. 



Harden and Norris : " Proc, Roy. Soc., Lond.," B., 1910, 82, 645. 



II Harden and Young : id., 1909, 8l, 336. 

 IT Kohl : Beih. hot. Centrlbl.," 1910, 29, 115. 

 ** Neuberg and Tir: " Biochem. Zeitschr.," 1911, 32, 323. 



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