Ectoine is a compatible solute that functions as a cell protector from various stresses, protecting cells and stabilizing biomolecules, and is widely used in medicine, cosmetics, and biotechnology. Microbial fermentation has been widely used for the large-scale production of ectoine, and a number of fermentation strategies have been developed to increase the ectoine yield, reduce production costs, and simplify the production process. Here, Corynebacterium glutamicum was engineered for ectoine production by heterologous expression of the ectoine biosynthesis operon ectBAC gene from Halomonas elongata, and a series of genetic modifications were implemented. This included introducing the de3 gene from Escherichia coli BL21 (DE3) to express the T7 promoter, eliminating the lysine transporter protein lysE to limit lysine production, and performing a targeted mutation lysC^S301Y on aspartate kinase to alleviate feedback inhibition of lysine. The new engineered strain Ect10 obtained an ectoine titer of 115.87 g/L in an optimized fed-batch fermentation, representing the highest ectoine production level in C. glutamicum and achieving the efficient production of ectoine in a low-salt environment.

中文翻译：

---

谷氨酸棒杆菌代谢工程高效生产四氢嘧啶

Ectoine 是一种相容性溶质，可作为细胞保护剂免受各种压力，保护细胞并稳定生物分子，广泛应用于医药、化妆品和生物技术。微生物发酵已广泛用于四氢嘧啶的大规模生产，并开发了多种发酵策略来提高四氢嘧啶产量、降低生产成本、简化生产工艺。在此，通过异源表达来自延长盐单胞菌的四氢嘧啶生物合成操纵子ectBAC基因，对谷氨酸棒杆菌进行了改造以生产四氢嘧啶，并实施了一系列遗传修饰。这包括引入来自大肠杆菌BL21（DE3）的de3基因来表达T7启动子，消除赖氨酸转运蛋白lysE以限制赖氨酸的产生，并对天冬氨酸激酶进行靶向突变lysC ^S301Y以减轻赖氨酸的反馈抑制。新工程菌株Ect10在优化的补料分批发酵中获得了四氢嘧啶滴度115.87 g/L，代表了谷氨酸棒杆菌中最高的四氢嘧啶生产水平，实现了低盐环境下四氢嘧啶的高效生产。