School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, Qixia District, Nanjing, China.
College of Life Sciences, Nanjing Normal University, Qixia District, Nanjing, China.
Biotechnol J. 2023 Aug;18(8):e2300052. doi: 10.1002/biot.202300052. Epub 2023 May 15.
In order to find a more effective way to obtain docosahexaenoic acid (DHA) rich lipid from Schizochytrium sp., a widespread propionate wastewater (PW) is used. PW is a common industrial and domestic wastewater, and transforming it into valuable products is a potential treatment method. Schizochytrium sp. is a rapidly growing oleaginous organism, which has been used commercially for DHA production. Herein, PW is completely used for DHA production by Schizochytrium sp. by genetic engineering and fermentation optimization, which can alleviate the increasingly tense demand for water resources and environmental pollution caused by industrial wastewater. Firstly, the methylmalonyl-CoA mutase (MCM) was overexpressed in Schizochytrium sp. to enhance the metabolism of propionate, then the engineered strain of overexpressed MCM (OMCM) can effectively use propionate. Then, the effects of PW with different concentration of propionate were investigated, and results showed that OMCM can completely replace clean water with PW containing 5 g L propionate. Furthermore, in the fed-batch fermentation, the OMCM obtained the highest biomass of 113.4 g L and lipid yield of 64.4 g L in PW condition, which is 26.8% and 51.7% higher than that of wild type (WT) in PW condition. Moreover, to verify why overexpression of MCM can promote DHA and lipid accumulation, the comparative metabolomics, ATP production level, the antioxidant system, and the transcription of key genes were investigated. Results showed that ATP induced by PW condition could drive the synthesis of DHA, and remarkably improve the antioxidant capacity of cells by enhancing the carotenoids production. Therefore, PW can be used as an effective and economical substrate and water source for Schizochytrium sp. to accumulate biomass and DHA.
为了寻找更有效的方法从裂殖壶菌中获得富含二十二碳六烯酸（DHA）的脂质，我们使用了广泛存在的丙酸废水（PW）。PW 是一种常见的工业和家庭废水，将其转化为有价值的产品是一种潜在的处理方法。裂殖壶菌是一种生长迅速的油脂生物，已被商业化用于 DHA 生产。在此，通过遗传工程和发酵优化，裂殖壶菌完全利用 PW 生产 DHA，这可以缓解工业废水日益紧张的水资源需求和环境污染问题。首先，在裂殖壶菌中过表达甲基丙二酰辅酶 A 变位酶（MCM）以增强丙酸的代谢，然后过表达 MCM 的工程菌株（OMCM）可以有效利用丙酸。然后，研究了不同浓度 PW 中的丙酸的影响，结果表明 OMCM 可以完全替代含有 5 g/L 丙酸的 PW 清洁水。此外，在分批补料发酵中，OMCM 在 PW 条件下获得了 113.4 g/L 的最高生物量和 64.4 g/L 的脂质产率，分别比 PW 条件下的野生型（WT）提高了 26.8%和 51.7%。此外，为了验证为什么过表达 MCM 可以促进 DHA 和脂质积累，我们进行了比较代谢组学、ATP 产生水平、抗氧化系统和关键基因的转录研究。结果表明，PW 条件下诱导的 ATP 可以驱动 DHA 的合成，并通过增强类胡萝卜素的产生显著提高细胞的抗氧化能力。因此，PW 可以作为裂殖壶菌积累生物量和 DHA 的有效且经济的底物和水源。
