Comparative Transcriptomic Analysis on the Effect of Sesamol on the Two-Stages Fermentation of Aurantiochytrium sp. for Enhancing DHA Accumulation

Aurantiochytrium is a well-known long-chain polyunsaturated fatty acids (PUFAs) producer, especially docosahexaenoic acid (DHA). In order to reduce the cost or improve the productivity of DHA, many researchers are focusing on exploring the high-yield strain, reducing production costs, changing culture conditions, and other measures. In this study, DHA production was improved by a two-stage fermentation. In the first stage, efficient and cheap soybean powder was used instead of conventional peptone, and the optimization of fermentation conditions (optimal fermentation conditions: temperature 28.7 °C, salinity 10.7‰, nitrogen source concentration 1.01 g/L, and two-nitrogen ratio of yeast extract to soybean powder 2:1) based on response surface methodology resulted in a 1.68-fold increase in biomass concentration. In the second stage, the addition of 2.5 mM sesamol increased the production of fatty acid and DHA by 93.49% and 98.22%, respectively, as compared to the optimal culture condition with unadded sesamol. Transcriptome analyses revealed that the addition of sesamol resulted in the upregulation of some genes related to fatty acid synthesis and antioxidant enzymes in Aurantiochytrium. This research provides a low-cost and effective culture method for the commercial production of DHA by Aurantiochytrium sp.