Regulation of polyunsaturated fatty acids synthesis by enhancing carotenoid-mediated endogenous antioxidant capacity in Schizochytrium sp

Schizochytrium sp. has been widely used for synthesizing polyunsaturated fatty acids (PUFAs). Cell damage resulted from oxidative stress is inevitable under aerobic fermentation conditions. In this study, the correlation between oxidative stress regulated by carotenoids biosynthesis and fatty acid accumulation in Schizochytrium sp. was investigated by fluoridone treatments. Results showed that addition of 50 mg/L fluoridone at 24 h increased β-carotene by 56.8% and eicosapentaenoic acid (EPA) content 44.2%, respectively. Compared to the control group, intracellular reactive oxidative species (ROS) activity in the fluoridone group reduced by 21.8% at 48 h and decreased afterwards to a stable level. Metabolomics analysis showed that the addition of fluoridone could supply more substrates for PUFAs biosynthesis by delaying cell growth and induce β-carotene accumulation in order to potentially resist ROS and protect PUFAs from oxidization. This work proposed a new perspective that the regulation of carotenoids biosynthesis could promote the accumulation of PUFAs by improving endogenous antioxidant capacity.