Eicosapentaenoic acid and docosahexaenoic acid production potential of microalgae and their heterotrophic growth

Twenty microalgal strains were investigated in photoautotrophic flask cultures for their potential for eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) production. The highest EPA proportion (% of total fatty acids) was produced by Monodus subterraneus UTEX 151 (34.2%), followed by Chlorella minutissima UTEX 2341 (31.3%) and Phaeodactylum tricornutum UTEX 642 (21.4%). The highest DHA proportion (% of total fatty acids) was obtained in Crypthecodinium cohnii UTEX L1649 (19.9%), followed by Amphidinium carterae UTEX LB 1002 (17.0%) and Thraustochytrium aureum ATCC 28211 (16.1%). Among the 20 strains screened, the EPA yield was high in M. subterraneus UTEX 151 (96.3 mg/L), P. tricornutum UTEX 642 (43.4 mg/L), Chl. minutissima UTEX 2341 (36.7 mg/L), and Por. cruentum UTEX 161 (17.9 mg/L) owing to their relatively high biomass concentrations. The DHA yield was high in C. cohnii UTEX L1649 (19.5 mg/L) and A. carterae UTEX LB 1002 (8.6 mg/L). Heterotrophic growth of these 20 microalgae was also tested on two different carbon sources, acetate and glucose. All microalgae except Nannochloropsis oculata UTEX LB 2164 showed growth on glucose (5 g/L) under heterotrophic conditions. Twelve of them could grow heterotrophically when acetate (1 g/L) was used as their sole carbon and energy source.