BACTERIAL ENZYMES. 39 



ilized by heating to 60 C., caused a solid coagulation of 

 sterile milk in a few da vs. 



A small number of bacteria have also been encoun- 

 tered that bring about coagulation of milk with a dis- 

 tinctly alkaline reaction. This function has been 

 noticed in bacteria isolated from milk, and especially 

 in bacterium pseudodiphtheriticum isolated from cows' 

 milk (Bergey). 



Sugar-splitting enzymes are very common in bacteria. 

 This function varies in different species as seen in the 

 different end-products that are formed. Buchner suc- 

 ceeded in isolating the sugar-splitting enzyme (zymase) 

 of yeast-cells, and when thus isolated it still possesses 

 the power of inducing active fermentation of sugar. It 

 is believed that the sugar-splitting enzymes of bacteria 

 are similar in character to the zymase of yeast-cells. 

 The splitting up of carbohydrates appears to be brought 

 about by the bacteria for the purpose of obtaining oxygen, 

 as indicated by the nature of the end-products formed, 

 and also by the conditions under which it may be car- 

 ried out i. <?., the absence of atmospheric oxygen. 



The splitting of the carbohydrate molecule may be 

 illustrated as follows : 



C 6 H 12 6 = 2C 2 H 6 + 2CO, 

 Grape sugar == 2 alcohol + 2 carbon dioxid. 



or C 6 H 12 6 = 2G.H.O, 



Grape sugar = 2 lactic acid. 



or C 6 H 12 O 6 == 3C 2 H 4 O 2 



Grape sugar = 3 acetic acid. 



According to Theobald Smith * all facultative anaero- 

 bic bacteria 2 form acids from carbohydrates, while the 

 strict aerobic bacteria do not have this function, or 



i Theobald Smith: Centralblatt fur Bacteriologie, Bd. xviii. 

 2See "aerabic" and "anaerobic" bacteria. 



