58 BACTERIAL FERMENTATIONS 



quently difficult problems of chemical analysis. The 

 chemists typically inoculated a nutrient solution containing 

 a relatively pure amino acid with a piece of decaying meat, 

 waited several months for the microbial activity to cease, 

 and then identified the products. The bacteriologists typi- 

 cally inoculated a pure culture of a Clostridium into a 

 complex protein hydrolyzate and in the end were unable 

 to identify either the specific amino acids decomposed or 

 all of the products formed. 



One of the most substantial contributions in both a 

 chemical and microbiological sense to knowledge of the 

 anaerobic decomposition of amino acids was made by 

 Stickland in 1934. 1 He studied the action of washed sus- 

 pensions of Clostridium sporogenes on amino acids. By the 

 use of both manometric and dye-coupling techniques he 

 demonstrated that, whereas most single amino acids are 

 not readily attacked by CI. sporogenes, certain pairs of 

 amino acids are decomposed rapidly by a coupled oxidation- 

 reduction reaction; one member of the pair is oxidized 

 while the other member is reduced. The simplest example 

 of this type of reaction is that involving alanine and glycine. 

 As the following equations show, the oxidation of alanine 

 to acetic acid, carbon dioxide, and ammonia is coupled with 

 the reduction of 2 moles of glycine to acetic acid and 

 ammonia. 



CH3CHNH2COOH + 2H 2 — > 



CH3COOH + C0 2 + NH 3 + 4H (1) 



2CH2NH2COOH + 4H — > 2CH3COOH + 2NH 3 (2) 



CH3CHNH2COOH + 2CH 2 NH 2 COOH + 2H 2 — >- 



3CH 3 COOH + 3NH 3 + C0 2 (3) 



Certain other amino acids react in similar ways. Other 



