1967 Volume 13 Issue 4 Pages 365-380
Inosine formation by mutants of Bacillus subtilis in chemically defined medium was investigated, using strains No. 11413 (adenine-histidine-requiring) and No. 11023-4 (adenine-requiring).
Only adenine (or its congeners) was able to regulate the formation of inosine in the growing culture, and it was also found that adenine was a specific requirement for inhibition of inosine formation by non- growing washed cells of these mutants.
Purines other than adenine, pyrimidines, and amino acids were all inactive in inhibitory effect on inosine formation by these washed cells. However, the optimum concentration of adenine for the nucleoside formation in growing culture was greatly altered by certain substances. AICA and amino acid mixture(artificial L-amino acid mixture of "casamino acids" type) were found to have a strong adenine-sparing action, while AICA-R, L-histidine, purines, etc., had no such action. AICA inhibited adenine deamination reaction of the intact cells in some cases, which might be one of the mechanisms of the sparing action of the amine. On the other hand, effect of the amino acid mixture on the deamination reaction was not clear under the conditions examined. Another significant effect of the amino acid mixture was its promotive action on the cell growth accompanied with a marked increase in the amount of inosine produced. AICA and some purine compounds were slightly stimulative, but far less than the amino acid mixture in the stimulation of the production.
