Abstract
Biochemical production of vitamin K (K_2 and K_3) was studied using microorganisms screened from soil samples. Fermentative production of menaquinone-4 (MK-4, one of vitamin K_2) was established by isolation of MK-4-producing mutants from Flavobacterium sp. 238-7, excretion of MK-4 into the culture broth with a detergent, and optimization of the conditions for jar-fermentor cultivation. Menadione (MD)-producing process was basically the microbial conversion of 2-methylnaphthalene (2MN) to MD via 2-methyl-1-naphthol (2MNOH). Methylethylketone utilizing bacteria screened were the good convertors of 2MN to 2MNOH. Ethylxanthate or diethyldithiocarbamate was a specific inhibitor for 2-naphthoic acid (side-product) production.
