BACTERIA OF BUTYRIC FERMENTATION i6i 



The chemical formula of the butyric reaction may be expressed ,5^ 



thus : — 



CgHiaOg [by simple decomposition] = 2C3H6O3 

 Glucose Lactic acid 



Or, CiaH-aOu + H2O = 4C3H6O3 



Lactose I.ACtic acid 



which is followed by the fermentation of the lactic acid by the 

 agency of the butyric ferment : — 



2C3H6O3 = C^HgOa + CO2 + 2H., 



Lactic acid Butyric acid Carbonic Free 



acid gas hydrogen 



These three bodies may be accepted as the most important, 

 but not the only, products of butyric fermentation. Although 

 according to Pasteur's researches the butyric acid ferment 

 performs its functions anaerobically, many butyric organisms act 

 in the presence of oxygen (Hueppe, Fitz), and yield somewhat 

 different products. For example, Gruber has pointed out that one 

 or two species produce butyl alcohol. All of them, however, fer- 

 ment most actively at a temperature at or about blood heat, and 

 the spores are able to withstand boiling for several minutes 

 (Fitz). Hence butyric organisms may be found in sterilised milk. 

 It will be noted that as in the lactic fermentation, so in the butyric, 

 the results are not due to one species only. We must now con- 

 sider some of the chief organisms associated with butyric fer- 

 mentation. 



Bacteria associated with butyric fermentation. — Previously to 1880 

 the only work which had been done in the elucidation of the 

 bacterial origin of butyric fermentation had been accomplished by 

 Prazmowski and Pasteur ; the former designating the organism 

 he found Clostridium butyricum, and the latter naming his "in- 

 fusoire " Vibrion butyrique. Prazmowski emphasised the motility 

 and resistance of the bacillus, and found that the latter was due to 

 the spores produced by the organism. These spores were able to 

 withstand boiling for several minutes. Fitz went so far as to say 

 that butyric spores could resist boiling for twenty minutes. Praz- 

 mowski was unable to obtain pure cultures. Clostridium butyricum 

 grows most readily at a temperature of about 40"" C, and is very 

 widely distributed in nature. It is capable of dissolving cellulose, 

 and therefore plays a part in the cellulose fermentation which is 

 employed in various maceration industries. It is generally held 

 that in such fermentations there is symbiotic action between the 

 butyric bacillus and an organism incapable of causing " retting " 



L 



