60 BACTERIAL FERMENTATIONS 



mation of several products among which succinate, acetate, 

 carbon dioxide, and ammonia were positively identified. 

 Two years later, Brasch 4 isolated from a medium containing 

 glutamate as the only carbon and nitrogen source an 

 obligate anaerobic bacterium which he identified with 

 Bienstock's Bacillus putrificus and reported that it could 

 ferment glutamate with the formation of ammonia, formate, 

 and butyrate. At about the same time Liebert, 5 working 

 in Beijerinck's laboratory, described a fermentation of uric 

 acid by an organism he had isolated from a uric acid enrich- 

 ment culture and named Bacillus acidi-urici. Other experi- 

 ments on the anaerobic decomposition of single nitrogenous 

 compounds made during the same period were mostly 

 carried out with mixed cultures. They showed that several 

 other amino acids including lysine, arginine, aspartate, 

 serine, and alanine probably can be fermented. 



Following this flurry of research on amino acid fermenta- 

 tions, interest in this subject subsided and was not reawak- 

 ened until some twenty-five years later when van Niel 6 began 

 to investigate the possibility that amino acids and purines 

 can serve as energy sources for some fermentative bacteria 

 just as carbohydrates do for others. He also made use of 

 the enrichment culture method in a search for organisms 

 that can attack various nitrogenous compounds in the 

 absence of oxygen, and he found, in confirmation of Brasch 

 and Liebert, that glutamate and urate are particularly sus- 

 ceptible to decomposition. With both substrates Clostridia 

 appeared to be the predominant organisms in the enrich- 

 ment cultures. 



My associates and I continued the study of the anaerobic 

 bacteria that can be obtained from soil and decomposing 

 organic materials by the use of enrichment cultures supplied 

 with single nitrogenous compounds, and over a period of 

 years we isolated a number of species capable of fermenting 



