Bacterial fermentation of creatinine. I. Isolation of N-methyl-hydantoin.

Although creatinine is, other than urea, the most important nitrogenous end product excreted by many animals, very little is known about its metabolic pathway in soil bacteria. Some incomplete studies have been made by early workers (Ackerman, 1913, Linneweh, 1930), mostly with putrefactive bacteria, and they claimed to have identified, besides ammonia, methyl-hydantoin as an end product. Dubos and Miller (1937), in a deliberate attempt to find a microorganism which could be used for a bio-assay of creatinine in the blood of higher animals, were the first to isolate from soil two aerobic strains (NC and HR), capable of growing specifically on creatinine. No attempt was made by these authors to study the complete metabolism of creatinine. However, they did observe that the oxidation of creatinine involves the formation of an adaptive enzyme and that urea and ammonia are the end products. Krebs and Eggleston (1939) have identified one of the strains of Dubos and Miller as a corynebacterium and have shown that a number of other compounds can be oxidized by this microorganism. The reversible transformation of creatinine to creatine and the oxidative breakdown of the latter by different strains of pseudomonads has been the subject of more recent papers (Kopper and Beard, 1947; Kopper and Robin, 1950; Roche et al., 1950; Akamatsu and Kanai, 1951; Akamatsu and Miyashita, 1952; Nimmo-Smith and Appleyard, 1956; Appleyard and Woods, 1956). However, the method of fermentation of creatinine by anaerobic bacteria still remained unknown. In view of these facts it was of considerable interest to investigate the complete pathway of the bacterial fermentation of creatinine by a pure culture of a soil bacterium. The present paper deals with the first steps in the anaerobic degradation process of creatinine