Microbial formation of nitrosopyrrolidine from nitrosoproline

The fate of orally administered NPro was determined in rats. Unchanged NPro could be recovered in the urine, while NPy was detected in the faeces of two of three rats tested. After successive administration of NPro to the same rats, their intestinal contents were inoculated into media containing NPro to test for NPy formation. Decarboxylation of NPro occurred in the faeces cultures from those rats whose faeces had contained NPy. When the faeces from 10 mice were inoculated into the NPro media, all gave negative reactions for NPro decarboxylation. However, when the faeces of eight rats and those of 15 rabbits were tested, two rats and one rabbit exhibited NPy formation. L-Pro and NPro decarboxylase reactions were tested on 24 strains of bacteria and three strains each of E. coli and Proteus mirabilis isolated from rat intestines. It was found that seven bacteria gave a positive reaction with L-pro decarboxylation, while only two species, both belonging to Pseudomonas, could decarboxylate NPro.