Production of Nucleic Acid Related Substances by Fermentative Processes: Part VI. Accumulation of 5′-Xanthylic Acid by Guanine-Requiring Mutants of Micrococcus glutamicusI. Isolation and Characterization of 5′-Xanthylic AcidII. Studies on Cultural Conditions

It was found that a guanine and adenine-requiring mutant of Micrococcus glutamicus accumulated the ultraviolet-absorbing substance in the culture fluid. A KY9978 strain, which accumulated the largest amount of the substance, we selected from the guanine auxotrophs derived from the guanineadenine doubleless mutant. The substance was isolated in a crystalline form from the culture fluid by the use of ion exchange resins, Diaion SA 21A and SK No. 1, and identified chemically and enzymatically as 5′-xanthylic acid, an intermediate from 5′-inosinic acid to 5′-guanylic acid on the purine nucleotide biosynthesis.