Accumulation of Nucleic Acid Derivatives by Bacteria Part I

Abstract

A newly isolated strain, which belongs to Bacillus, was mutated to adenine dependency by treatment with the mutagen, N-methyl-N'-nitro-N-nitrosoguanidine. The adeninerequiring strains, as expected, accumulated inosine. Cultural conditions for inosine synthesis de novo and the pathway of inosine formation in the mutated strain were investigated. 1) NH4C1 was the preferred nitrogen source. Addition of MnC12.4 H20 was effective for the accumulation of inosine. 2) In this fermentation process, hypoxanthine was formed first, and, after that, inosine was accumulated in the medium. When hypoxanthine was added in the medium, the formation of inosine greatly increased, and, after 90 hours, almost all the hypoxanthine added was converted to inosine. 3) Hypoxanthine-8-C14 was converted to labeled inosine by growing cells, but not converted to cellular RNA. Labeled inosine was formed from hypoxanthine-8-C14 and ribose-1-phosphate by intact cells or cell-free extract. It is presumed that the route of inosine accumulation in the adenine-auxotrophic mutant, Bacillus sp. No. 226, is as follows.