Production of Nucleic Acid-Related Substances by Fermentative Processes

The presence of psicofuranine in the fermentation medium caused the accumulation of a copious amount of 5′–XMP by Brevibacterium ammoniagenes. The accumulation of 5′–XMP in the medium was considered to be due to the inhibition of converting 5′–XMP to 5′–GMP by psicofuranine, which is known as a specific inhibitor of XMP aminase.

It was previously reported that in 5′–IMP fermentation with Br. ammoniagenes pantothenate and thiamine, in addition to biotin which was required for the growth of the microorganism, were exclusively required. This requirement for both vitamins was also observed in 5′–XMP production induced by the antibiotic.

The addition of manganese in excess to the fermentation medium promoted the bacterial growth greatly and inhibited IMP production, whereas XMP production induced by piscofuranine was not affected by the addition of excess manganese.

The accumulation of XMP induced by the antibiotic was completely suppressed by the presence of purine derivatives such as guanine, and xanthine derivatives, and partially by hypoxanthine.

5′–XMP was identified by chemical and enzymatic analyses and by UV absorption spectrum.