Effect of light stress on the production of lipid compounds by Schizochytrium sp. and its underlying mechanism

Light is a critical environmental factor influencing microbial growth and lipid synthesis. This study examined the effects of light stress on cell growth and lipid production of Schizochytrium sp.. Under light stimulation, Schizochytrium sp. exhibited changes in cell morphology, with a reduction in biomass by 18.21% compared to the control. However, lipid accumulation increased by 39.67% under light conditions compared to dark fermentation. Saturated fatty acids (SFAs), including C14:0 and C16:0, were 1.49 times higher in the light-treated group, indicating a greater propensity for neutral lipid formation. Although polyunsaturated fatty acids (PUFAs) slightly decreased, the proportion of EPA increased to 8.30%, which was 3.88 times higher than that of the control. Additionally, squalene and β-carotene contents under light stress increased by 21.17% and 33.8% respectively, highlighting the enhanced production of these compounds. Transcriptomics analysis indicated that light stress in Schizochytrium sp. upregulated genes for lipid biosynthesis and antioxidant responses, driving metabolic shifts to enhance oxidative stress tolerance and lipid accumulation.These findings provide valuable insights into the metabolic regulation of Schizochytrium sp. under light stress, offering new strategies for optimizing lipid and carotenoid production.