Enhanced eicosapentaenoic acid production by Navicula saprophila

Changes in the eicosapentaenoic acid (EPA) content of Navicula saprophila grown photoautotrophically and mixotrophically with the addition of acetate were examined in terms of their growth progress. Among four conditions, mixotrophic conditions in CO2-enriched (about 2%) atmosphere gave a maximum EPA content. As sodium acetate was added to the growth medium, the EPA content increased and reached a maximum value of 34.6 mg EPA g(-1) biomass in the early stationary growth phase. In contrast, under photoautotrophic conditions in CO2 enriched atmosphere, the EPA content decreased during this phase. EPA was localized as the fatty acid esters of monogalactosyl diacylglycerol, phosphatidylethanolamine and phosphatidylcholine, and the addition of acetate strongly enhanced production of the PC ester of EPA.