STUDIES ON INOSINE FERMENTATION-PRODUCTION OF INOSINE BY MUTANTS OF BACILLUS SUBTILIS

I. ISOLATION AND CHARACTERIZATION OF INOSINE-PRODUCING MUTANTS

Abstract

1. Various kinds of auxotrophic mutants were derived by X-ray irradiation from an adenine requiring mutant of Bacillus subtilis which accumulates hypoxanthine in the culture medium.
2. Among these mutants, some were found to have acquired the ability of accumulating inosine. Some mutants accumulated only inosine but not hypoxanthine, others both inosine and hypoxanthine in varying ratio. One of the adenine-histidine requiring mutants had the highest level of inosine productivity, and its productivity could be improved by further mutation.
3. A mutant which produced inosine alone was found to have almost lost the ability of degrading inosine to hypoxanthine. The genetic conversion of the pattern of such accumulation was discussed in connection with the inosine degradation ability.
4. The fermentation product was isolated by the use of ion exchange resin "Dowex-1, formate form", and by acetylation it was converted to 2′, 3′, 5′-tri-0-acetyl-inosine. Thus the fermentation product was identified as inosine by comparison with its authentic preparation.