High cell density cultivation for docosahexanoic acid production of Schizochytrium sp. BCC 25505

Docosahexanoic acid (22:6 n-3; DHA) is a polyunsaturated fatty acid that is essential for functional development and maintenance of human brain and is also involved in the prevention of cardiovascular diseases, improving neural and retinal development in infants. Schizochytriumsp. BCC 25505, a marine protist, can produce DHA at high yield.In this study, biomass and DHA production of this marine protist were carried out to avoid glucose repression and nitrogen limitation using high cell density cultivation technique. The use of high glucose concentration resulted in a slow growth rate and low biomass concentration. By employing central composite design and by pulsing 40 gL-1 glucose at a time yielded maximum biomass (77.3g.L-1) and DHA (18.5 gL-1) productions.Theoptimal conditions for maximizing DHA production of Schizochytrium sp. BCC 25505 calculated using Design expert software were validated in a 5L bioreactor cultivation, yielding at 97 h a maximum concentration of biomass and docosahexanoic acid of 70.8 and 14.1gL-1 respectively. This was further scaled up in 300 L bioreactor and 115.9 gL-1 biomass, 15.0 gL-1 DHA at 119 h were obtained. This optimal fermentation process can provide a low cost production of DHA, which can be used in industrial scale.