抄録
Sulfonamide-resistant mutant strains were derived from a mutant strain, K3-15, of Flavobacterium sp. 238-7 to improve the menaquinone (MK)-4 productivity. A mutant strain, SP0736, with resistance to 50 μg/l of sulfapyridine in a chemically-defined medium, had improved productivity of MK-4. By optimization of the culture conditions, the mutant strain SP0736 produced 280 mg/l of the culture broth (240 mg/l of MK-4 and 40 mg/l of MK-6) at 6 days of cultivation. The productivity of strain SP0736 was 50% higher than that of the parent strain, K3-15.
