Production of nucleic acid-related substances by fermentative processes. 28. Accumulation of 5' inosinic acid by a manganese-insensitive mutant of Brevibacterium ammoniagenes.

A manganese-insensitive mutant, KY 13105, of Brevibacterium ammoniagenes which accumulates considerable amounts of 5' inosinic acid (IMP) in the presence of 100 to 1,000 mug of Mn(2+) per liter was obtained from an IMP-producing mutant of a manganese-sensitive strain, KY 13102. The effects of Mn(2+) at 0 to 30 mug/liter on IMP accumulation by KY 13105 were similar to those by KY 13102. However, the accumulation of IMP by KY 13105 was not affected by 100 to 1,000 mug of Mn(2+) per liter, showing a clear difference from KY 13102. The accumulation of IMP by KY 13105 was always accompanied by cellular morphological changes irrespective of Mn(2+) concentration. In the presence of Mn(2+), factors which affect IMP accumulation by KY 13105 were examined. Most of the nutrients tested stimulated IMP accumulation at a relatively low concentration (2 g/liter). Iron, calcium, and zinc were found to be essential for IMP accumulation and were independent of Mn(2+). Biotin regulated the growth but not the accumulation of IMP. Under limited or surplus amounts of Mn(2+), the dynamics of IMP fermentation were followed. Under both conditions, the fermentations proceeded in a similar way. The morphological changes were found to be closely related to IMP accumulation.