[Nitrosoguanidine induction of mutants in Salmonella cholerae suis]

On treatment two strains of Salmonella cholerae suis with nitrosoguanidine and using Ledeberg's contact technique, some 100 colonies of one of the strains were obtained, seven out of which were auxotrophic. These seven mutants were auxotropic, of which three -- to tyrosine, two -- to adenine, one -- to glutamic acid and one -- to histidine. The mutant of the second Salmonella cholerae suis strain is auxotrophic to tyrosine, xanthine and adenine. The colonies of these mutants are smaller. Their growth in MPB is sparse. Their fermentation is deleyed by a higher degree. The mutant, auxotrophic to tyrosine, xanthine and adenine, manifests a delayed fermentation in ramnose and is negative to lysine and to ornithodecarboxylase. The mutant, auxotrophic to tyrosine, possesses a negative argininedehydrolase. Mutants Nos 3,5 and 6 are auxotrophic to adenine, glutamic acid and histidine, respectively, and are with a negative ornithodecarboxylase. Four of the eight mutants were for tested for pathogenicity to white mice. All manifested a decreased pathogenicity, ranging from 1000- to 10,000-fold lower.