Abstract
High DHA production cost caused by low DHA titer and productivity of the current Schizochytrium strains is a bottleneck for its application in competition with traditional fish-oil based approach. In this study, atmospheric and room-temperature plasma with iodoacetic acid and dehydroepiandrosterone screening led to three mutants, 6–8, 6–16 and 6–23 all with increased growth and DHA accumulations. A LC/MS metabolomic analysis revealed the increased metabolism in PPP and EMP as well as the decreased TCA cycle might be relevant to the increased growth and DHA biosynthesis in the mutants. Finally, the mutant 6–23, which achieved the highest growth and DHA accumulation among all mutants, was evaluated in a 5 L fermentor. The results showed that the DHA concentration and productivity in mutant 6–23 were 41.4 g/L and 430.7 mg/L/h in fermentation for 96 h, respectively, which is the highest reported so far in literature. The study provides a novel strain improvement strategy for DHA-producing Schizochytrium.
Highlights
Docosahexaenoic acid (DHA; C22:6, n-3) has been demonstrated to be beneficial to human health
The results showed that the lethal rate of Schizochytrium American Type Culture Collection (ATCC) 20888 reached 90% when the concentration of iodoacetic acid and DHEA was over 160 and 40 mg/L, respectively (Supplementary Figures S1A, S1B)
It was found that the growth of Schizochytrium ATCC 20888 was significantly inhibited over 90% when the concentration of both selected agents together was over 50 mg/L (Figures 1B,C)
Summary
Docosahexaenoic acid (DHA; C22:6, n-3) has been demonstrated to be beneficial to human health. It was reported that DHA is an essential component of human cerebral cortex and retina, and has roles in the nervous development of infants and children. It has positive effect in the preventing cardiovascular diseases and anti-inflammatory and anti-tumor effects (Dessi et al, 2013). Thraustochytrid, a heterotrophic algae-like protist, Schizochytrium grows faster, accumulates more biomass and has higher DHA ratio in total fatty acid, it contains docosapentaenoic acid (DPA; C22:5, n-6), which is essential fatty acid
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