FERMENTATIONS OF NITROGENOUS COMPOUNDS 59 



amino acids that can be oxidized include leucine and valine 

 which are converted to the branched-chain fatty acids with 

 one less carbon atom. Some of the amino acids that serve 

 as oxidants, such as arginine, are reduced like glycine with 

 the formation of ammonia. Others do not give ammonia 

 but are reduced with the opening of a ring; proline for 

 example is converted to S-aminovaleric acid (equation 4) . 



CH 2 — CH 2 CH 2 — CH 2 



CR 2 CH— COOH + 2H — > CH 2 CH 2 — COOH (4) 



\/ \ 



NH NH 2 



Proline 5-Aminovaleric acid 



These reactions provide mechanisms for the decomposition 

 of a variety of amino acids. Stickland in fact suggested that 

 they could account for most if not all of the anaerobic 

 decomposition of amino acids. In support of this idea, 

 Clifton, Cohen, Nisman, and others 2 later showed that some 

 fifteen species of Clostridia, including CI. botulinum, CI. 

 butyricum, and CI. histolyticum, make use of the Stickland 

 reaction. However, the occurrence of this type of amino 

 acid decomposition in many Clostridia in no way excluded 

 the possibility that other mechanisms for amino acid break- 

 down could also be operative and have quantitative 

 significance. 



Considerably before the work of Stickland, the ferment- 

 ability of single amino acids had already been observed by 

 Naviasky, by Brasch, and by Liebert. Naviasky 3 was per- 

 haps the first investigator to observe the anaerobic decom- 

 position of a purified nitrogenous compound by a single 

 bacterium. In 1908 he showed that a pure culture of Bacil- 

 lus proteus vulgaris could ferment asparagine with the for- 



