Heterotrophic production potential of omega-3 polyunsaturated fatty acids by microalgae and algae-like microorganisms

Twenty microbial strains were screened for their potential of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) production using heterotrophic flask cultures on two different carbon sources, glucose (5 g L-1) and acetate (1 g L-1). Of the 20 microalgae tested, 19 strains showed growth on glucose, whereas only 12 of them could grow on acetate. Glucose was the preferred carbon source for growth, and EPA and DHA production. There was a complete absence or a marked decrease in EPA and DHA contents in all the microalgae except in Amphidinium sp. CS-259 while acetate was used as the sole carbon and energy source. The EPA yields of Amphidinium carterae Hullburt UTEX LB 1002 (8.3 mg L-1) and Schizochytrium aggregatum Goldstein et Belsky ATCC 28209 (9.3 mg L-1) on glucose were higher than those produced by all the other microalgae when grown on acetate or glucose. Amphidinium sp. CS-259 while grown on acetate had the highest EPA proportion (20.7% of total fatty acids) which was higher than those produced by all the other microalgae when grown on acetate or glucose. Crypthecodinium cohnii (Seligo) Chatton UTEX L1649, the heterotrophic dinoflagellate grown on glucose had the highest DHA yield (15.0 mg L-1) due to its significantly high biomass concentrations (1.9 g L-1).