The aim of the study was to evaluate the potential of acetate as a carbon source by examining the fermentation performance of Schizochytrium limacinum B4D1 and its effects on metabolism using physiology and transcriptomics studies. The results demonstrated that, while the metabolic rate of acetate in S. limacinum B4D1 was lower than glucose, it increased the content of docosahexaenoic acid (DHA) in the total fatty acids. Transcriptomic analysis indicated that the use of acetate as a carbon source significantly upregulated the acetyl-CoA synthetase gene, which increased the source of acetyl-CoA for fatty acid biosynthesis. Moreover, the upregulation of polyunsaturated fatty acid enzymes promoted the polyketide synthase (PKS) pathway of fatty acid synthesis, resulting in an increase in DHA content. Meanwhile, the upregulation of genes such as long-chain acyl-CoA synthetase and 3-hydroxyacyl-CoA dehydrogenase enhanced the β-oxidation process of saturated fatty acids in mitochondria, while the downregulation of acyl-CoA oxidase and catalase genes resulted the β-oxidation process of polyunsaturated fatty acids in peroxisomes was inhibited, leading to an increased proportion of DHA in the total fatty acids. Thus, these changes in gene expression contributed to the increased proportion of DHA in the total fatty acids.

该研究的目的是通过生理学和转录组学研究检测Schizochytrium limacinum B4D1的发酵性能及其对代谢的影响，从而评估乙酸盐作为碳源的潜力。结果表明，虽然S. limacinum中乙酸盐的代谢率B4D1低于葡萄糖，它增加了总脂肪酸中二十二碳六烯酸（DHA）的含量。转录组学分析表明，使用乙酸盐作为碳源可显着上调乙酰辅酶 A 合成酶基因，从而增加脂肪酸生物合成所需的乙酰辅酶 A 来源。此外，多不饱和脂肪酸酶的上调促进了脂肪酸合成的聚酮合酶（PKS）途径，导致DHA含量增加。同时，长链酰基辅酶A合成酶和3-羟酰基辅酶A脱氢酶等基因的上调增强了线粒体中饱和脂肪酸的β-氧化过程，而酰基辅酶A氧化酶和过氧化氢酶基因的下调导致了β-过氧化物酶体中多不饱和脂肪酸的氧化过程受到抑制，导致总脂肪酸中DHA的比例增加。因此，这些基因表达的变化导致了总脂肪酸中 DHA 比例的增加。