Enhancement of docosahexaenoic acid production by Schizochytrium sp. using a two-stage oxygen supply control strategy based on oxygen transfer coefficient

Aims: To improve the yield and productivity of docosahexaenoic acid (DHA) by Schizochytrium sp. in terms of the analysis of microbial physiology.Methods and Results: A two-stage oxygen supply control strategy, aimed at achieving high concentration and high productivity of DHA, was proposed. At the first 40 h, K_La was controlled at 150.1 h^-1 to obtain high μ for cell growth, subsequently K_La was controlled at 88.5 h^-1 to maintain high q_p for high DHA accumulation. Finally, the maximum lipid, DHA content and DHA productivity reached 46.6, 17.7 g l^-1 and 111 mg l^-1 h^-1, which were 43.83%, 63.88% and 32.14% over the best results controlled by constant K_La.Conclusions: This paper described a two-stage oxygen supply control strategy based on the kinetic analysis for efficient DHA fermentation by Schizochytrium sp.Significance and Impact of the study: This study showed the advantage of two-stage control strategy in terms of microbial physiology. As K_La is a scaling-up parameter, the idea developed in this paper could be scaled-up to industrial process and applied to other industrial biotechnological processes to achieve both high product concentration and high productivity.