Production of menaquinone (vitamin K-2)-7 by Bacillus subtilis

Menaquinone-7 (MK-7) is a highly bioactive homologue of vitamin K. We obtai ned a diphenylamine-resistant mutant strain D200-41 from Bacillus subtilis strain MH-I which was isolated from fermented soybeans, natto, The mutant s train exhibited decreased production of MK-6, Using strain D200-41, efficie nt production of MK-7 was achieved. We found that, compared with an agitate d and aerated culture, production of MK-7 was increased by static culture. The sporulation of the cells progressed more slowly in a static culture tha n in an agitated culture. The maximum concentration of MK reached about 60 mg/l in a medium containing 10% soybean extract, 5% glycerol, 0.5% yeast ex tract and 0.05% K2HPO4 (pH 7.3) when D200-41 cells as well as MH-1 cells we re statically cultured at 45 degreesC for 5 d after being cultured with sha king at 37 degreesC for 1 d.