Effects of homoserine dehydrogenase deficiency on production of cytidine by mutants of Bacillus subtilis

A homoserine-requiring mutant, Bacillus subtilis strain No, 615, was isolated from a cytidine-producing mutant strain No. 515. The homoserine dehydrogenase activity of strain No. 615 was reduced to less than 1/50 of that of No, 515, Strain No. 615 accumulated 23.5 mg/ml cytidine in a medium containing 16% glucose, and strain No. 515 accumulated 18.8 mg/ml cytidine under the same conditions. The effects of glucose concentration on cytidine production were examined, and strain No. 615 accumulated 30.2 mg/ml cytidine in a medium containing 20% glucose.