ABSTRACT
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(L) a was controlled at 150·1 h(-1) to obtain high µ for cell growth, subsequently K(L) a 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(L) a. 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(L) a 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.
