Fermentation Putrefaction 47 



Many of these activities are harmless, and indeed ad- 

 vantageous, though the fact that they are not infre- 

 quently accompanied by chemic changes, some of which 

 are poisonous, makes it necessary to watch and time their 

 operations lest acridity, acidity, insipidity, or toxicity of 

 the food replace the desired effect. 



Briefly considered, the best known phenomena resulting 

 from bacterial energy are as follows: 



1. Fermentation. Fermentation is a chemic transfor- 

 mation of carbohydrates resulting from the activity of 

 micro-organisms. The alcoholic fermentation, which is a 

 familiar phenomenon to the layman as well as to the 

 brewer and chemist, depends upon the activity of a yeast- 

 plant, one of the saccharomyces fungi. The acetic-acid, 

 lactic-acid, and butyric-acid fermentations are caused by 

 their respective bacilli (Bacillus aceticus, Bacillus acidi 

 lactici, and Bacillus butyricus). A considerable number of 

 bacilli seem capable of converting milk-sugar into lactic 

 acid. There seems to be no specific micro-organism for 

 the lactic-acid fermentation, although Bacillus acidi lactici 

 is a powerful acid producer. There are also several bac- 

 teria which produce the acetic fermentation, though it is 

 generally attributed to a special common form, Mycoderma 

 aceti or Bacillus aceticus. The butyric fermentation 

 generally due to Bacillus butyricus may also be caused 

 by other bacilli. (For an exact description of the chemistry 

 of the fermentations reference must be made to special text- 

 books.*) 



2. Putrefaction. Putrefaction is a chemic disintegra- 

 tion of nitrogenous compounds resulting from the ac- 

 tivity of micro-organisms. The first step in the process 

 seems to be the transformation of the albumins into pep- 

 tones, then the splitting up of the peptones into gases, 

 acids, bases, and salts. Both fermentative and putrefactive 

 processes apparently take place through the agency of 

 enzymes produced by the bacteria. In the process the 

 innocuous albumins are frequently changed to toxalbumins, 

 and sometimes to peculiar putrefactive alkaloids known as 

 ptomains. 



* See " Enzymes and Their Applications," by Jean Effront, trans- 

 lated by S. C. Prescott, New York, 1902; " Micro-organisms and Fer- 

 mentation," by Alfred Jorgensen, translated by A. K. Miller and A. 

 E. Lennholm, London, 1900; and the many writings of Christian 

 Hansen. 



