PRODUCTION OF HIGH YIELDS OF DOCOSAHEXAENOIC ACID BY SCHIZOCHYTRIUM SP. STRAIN SR21

The culture conditions for high-yield production of docosahexaenoic ac id (DHA) by Schizochytrium sp. strain SR21 were investigated in a ferm enter. With increasing carbon (glucose) and nitrogen (corn steep liquo r and ammonium sulfate) sources (up to 12% glucose) in the medium, DHA productivity increased without a decrease in growth rate, i.e., 2.0, 2.7, and 3.3 g DHA/L/d with 6, 10, and 12% glucose, respectively. Even tually, 48.1 g dry cells/L and 13.3 g DHA/L were produced in 4 d with 12% glucose. DHA productivity was decreased with 15% glucose, i.e., 3. 1 g/L/d. With 12% glucose, the lipid content was 77.5% of dry cells, a nd DHA content was 35.6% of total fatty acids. The lipid was composed of about 95% neutral lipid and 5% polar lipid. In polar lipids, the co ntents of phosphatidyl choline (PC), phosphatidylethanolamine, and pho sphatidylinositol were 74, 11, and 5%, respectively. The PC profile wa s simple, 70% of PC molecules were 1-palmitoyl-2-DHA-PC and 1,2-di-DHA -PC. These results indicate that Schizochytrium sp. strain 21 is an ex cellent source for microbial DHA production, including not only the ac id form of DHA but also 2-DHA-PC.