Biosynthesis of fatty acids in the docosahexaenoic acid-producing bacterium Moritella marina strain MP-1

We have isolated the fatty acid biosynthetic (fab) gene cluster taking part in the synthesis of middle-chain fatty acids and a genomic segment which was homologous with the eicosapentaenoic acid-biosynthetic gene cluster from the docosahexaenoic acid (DHA)-producing bacterium Moritella marina strain MP-1. This segment was presumed to include the DHA-biosynthetic gene cluster of M. marina strain MP-1. When M. marina strain MP-1 was cultured in medium containing cerulenin, a fatty acid synthesis inhibitor, decreases in levels of middle-chain fatty acids and remarkable increases in levels of DHA were observed. These results suggest that the synthesis of middle-chain fatty acids works independently of the synthesis of DHA.