210 BIOLOGY OF SPECIALIZED GROUPS 



different species of butyric acid bacteria have been isolated. 

 Usually in the butyric acid fermentation, as in all of the 

 enzyme processes of this type, hydrogen, carbon dioxide, and 

 traces of fatty acids are produced in addition. 



Some of the butyric acid organisms, besides possessing 

 enzymes which will ferment practically all the carbohydrate 

 compounds, will also cause a fermentation of such substances 

 as glycerine, gum arabic, etc. Bacillus orthobutyricus is a 

 bacterium of this type. 



Some butyric acid bacteria, for example, Bacillus butyricus, 

 possess in addition to zymogenic enzymes also saprogenic 

 enzymes capable of disintegrating proteins. Consequently, 

 it is not uncommon to find butyric acid in putrefying sub- 

 stances. Butyric acid can also be produced by the splitting 

 of certain protein compounds. 



It is quite common for butyric acid bacteria to infect sour 

 milk containing lactic acid and disintegrate this acid and 

 what lactose may be remaining. The following reactions 

 show what takes place when lactose (a) and lactic acid (b) 

 are attacked: 



(a) Ci 2 H 22 O n 4- H 2 O = 4 CH 3 - CH(OH)COOH (lactic acid). 



(b) 2 CH 3 CH(OH)COOH + 2 O = CH 3 CH 2 CH 2 COOH 



(butyric acid) + 2 CO 2 + 2 H 2 O. 



Butyric acid bacterial enzymes are claimed by some writers 

 (Fischer) to be the indirect cause of symptomatic anthrax 

 and malignant oedema, two anaerobic disease processes. 



