Abstract
It was found that a mutant strain, K3-15, of Flavobacterium sp. 238-7 excreted menaquinone (MK) into culture medium supplemented with a detergent. Among 174 kinds of detergent tested, a nonionic detergent, Rikanon UA 5012 (polyoxyethylene oleyl ether), showed the highest ability as to induction of MK excretion into the medium without inhibiting cell growth. MK-4, which was newly formed in cells of the mutant strain, was selectively excreted into the medium, but MK-6, which was the original MK of the wild type strain, was hardly excreted. In the presence of 0.05% Rikanon UA 5012, the MK-4 productivity increased about 20% compared to that without the detergent, and the total amount of MK was 39 mg/1 of culture broth.
