School of Life Science and Technology, Inner Mongolia University of Science and Technology, Baotou 014010, China.
Key Laboratory of Systems Microbial Biotechnology, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China; National Center of Technology Innovation for Synthetic Biology, Tianjin, China.
Sci Total Environ. 2022 Sep 10;838(Pt 3):156420. doi: 10.1016/j.scitotenv.2022.156420. Epub 2022 Jun 1.
Nannochloropsis oculata can accumulate large amounts of lipids under rare earth element (REE) conditions. However, the lipid accumulation mechanism responsible for REE stress has not been elucidated. In this study, the effects of cerium (the most abundant REE) on the growth and lipid accumulation of N. oculata were investigated. The de novo transcriptome data of N. oculata under cerium conditions were subsequently collected and analyzed. The results showed that N. oculata exhibited good cerium-resistance ability, showed slightly decrease in biomass but significantly increase in lipid content (55.8 % dry cell weight) under 6.0 mg/L cerium condition. Meanwhile, about 83.4 % cerium was biological fixated. Through transcriptome analysis, we found that the inhibited photosynthesis and carbon fixation pathways coupled with the stress-sensitive expression of ribosome biogenesis genes acclimatized the cells to REE stress. The active glycolysis pathway accelerated carbon flux to pyruvate and acetyl-CoA, and the upregulation of glycerol kinase and phosphatidate cytidylyltransferase genes further induced lipid accumulation. In addition, cerium downregulated the acyl-CoA oxidase and triacylglycerol lipase genes, which inhibited the degradation of lipids. Therefore, different responses to cerium demonstrate how N. oculata cells adapt to REE stress, and this knowledge may be used to extend our understanding of triacylglycerol (TAG) and the synthesis of other important metabolites.
眼点拟微绿球藻在稀土元素（REE）条件下可以积累大量的油脂。然而，负责 REE 胁迫的油脂积累机制尚未阐明。在这项研究中，研究了铈（最丰富的 REE）对眼点拟微绿球藻生长和油脂积累的影响。随后收集和分析了眼点拟微绿球藻在铈条件下的从头转录组数据。结果表明，眼点拟微绿球藻表现出良好的抗铈能力，在 6.0mg/L 铈条件下，生物量略有下降，但油脂含量（干细胞重量的 55.8%）显著增加。同时，约 83.4%的铈被生物固定。通过转录组分析，我们发现光合作用和碳固定途径受到抑制，核糖体生物发生基因的应激敏感表达使细胞适应 REE 应激。活跃的糖酵解途径加速了碳通量向丙酮酸和乙酰辅酶 A 的转化，甘油激酶和磷酸甘油酸胞苷转移酶基因的上调进一步诱导了油脂的积累。此外，铈下调了酰基辅酶 A 氧化酶和三酰甘油脂肪酶基因，从而抑制了油脂的降解。因此，对铈的不同反应表明眼点拟微绿球藻细胞如何适应 REE 胁迫，这一知识可能被用来扩展我们对三酰甘油（TAG）和其他重要代谢物合成的理解。
