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

Abstract

To improve the yield and productivity of docosahexaenoic acid (DHA) by Schizochytrium sp. in terms of the analysis of microbial physiology. 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. This paper described a two-stage oxygen supply control strategy based on the kinetic analysis for efficient DHA fermentation by Schizochytrium sp. 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.