62 BACTERIAL FERMENTATIONS 



or carbohydrates. Such a restricted diet is unusual even 

 among bacteria. Almost nothing is known about the dis- 

 tribution of this organism. 



Alanine is a good substrate for the enrichment of an 

 anaerobic spore former which we have called CI. propioni- 

 cum. 10 This organism, which also ferments serine, threo- 

 nine, lactate, pyruvate, and acrylate but not glucose, appears 

 to be rather widely distributed in soils since it has been 

 isolated in England, New Zealand, and several parts of the 

 United States. 



Uric acid enrichments from soil or mud invariably 

 lead to the development of Clostridia similar to Liebert's 

 Bacillus acidi-urici. Out of thirteen strains isolated from 

 different soils, 11 twelve proved to be indistinguishable from 

 Liebert's organism and therefore were called Clostridium 

 acidi-urici in accordance with modern nomenclature. The 

 remaining strain was physiologically similar to the other 

 twelve but was quite different morphologically, and there- 

 fore was called CI. cylindrosporum. Both species decom- 

 pose uric acid and certain other purines with great facility 

 but do not attack carbohydrates or amino acids, except 

 glycine and serine. In view of their highly developed 

 ability to attach purines and their wide distribution in soils, 

 these species may be largely responsible for the anaerobic 

 decomposition of uric acid in nature. 



Several attempts to obtain anaerobic bacteria capable of 

 growing on allantoin from several soil and mud samples 

 were unsuccessful, indicating that such organisms are not 

 common in nature; but eventually a vigorous fermentation 

 of allantoin was obtained starting with an inoculum of 

 black mud, and the causative organism was found to be a 

 large streptococcus which we have called 5. allantoicus. 12 

 This is one of the few species of the genus that is known 

 to obtain energy for growth from a nitrogenous compound. 



