Simultaneous DHA and organic selenium production by Schizochytrium sp.: a theoretical basis

Docosahexaenoic acid (DHA) and selenium (Se) are nutrients that confer several health benefits to both humans and animals. Widespread use of DHA in milk powder and health products requires large-scale mass production via Schizochytrium sp., while Se intended for human consumption is produced as organic Se via yeast. However, producing these nutrients on an industrial scale is constrained by various factors. We found that supplementing Schizochytrium sp. with Na₂SeO₃ (0.5 mg/L) improves its biomass and DHA production and also provides organic Se. De novo assembled transcriptome and biochemical indicators showed that Na₂SeO₃ promotes forming acetyl coenzyme A and L-cysteine via the glycerol kinase and cysteine synthase pathways, promoting DHA synthesis through the polyketide synthase pathway. However, high doses of Na₂SeO₃ (5 mg/L) limited the biomass of Schizochytrium sp. and DHA content. This study provided a theoretical basis for the simultaneous production of organic Se and DHA via Schizochytrium sp.