Key Laboratory of Industrial Biotechnology of the Ministry of Education, Laboratory of Applied Microorganisms and Metabolic Engineering, School of Biotechnology, Jiangnan University, Wuxi 214122, China.
Key Laboratory of Industrial Biotechnology of the Ministry of Education, Laboratory of Applied Microorganisms and Metabolic Engineering, School of Biotechnology, Jiangnan University, Wuxi 214122, China.
Bioresour Technol. 2022 Sep;359:127461. doi: 10.1016/j.biortech.2022.127461. Epub 2022 Jun 11.
L-valine is a valuable amino acid in mammals that is used as the main component of feed additives. The low efficiency of the fermentation titer limits the industrial application of L-valine. Here, an L-valine-producing strain of Escherichia coli was obtained using a multi-modular strategy. Initially, a chassis strain was generated by mutagenesis and high-throughput screening. The L-valine biosynthetic pathway and transport module were modified to improve the L-valine titer. Subsequently, the transcription factors associated with L-valine biosynthesis were investigated. Overexpression of PdhR and inhibition of the expression of RpoS promoted L-valine synthesis. Finally, the NADPH supply was enhanced after the introduction of the heterologous Entner-Doudoroff (ED) pathway from Zymomonas mobilis. The strain VAL38 produced 92 g/L L-valine in a 5-L bioreactor with a yield of 0.34 g/g glucose. This strategy is provided as a reference for improving the production performance of cell factories for L-valine and its derivatives.
L-缬氨酸是哺乳动物中一种有价值的氨基酸，可用作饲料添加剂的主要成分。发酵产率低限制了 L-缬氨酸的工业应用。在这里，我们采用多模块策略获得了一株产 L-缬氨酸的大肠杆菌菌株。首先，通过诱变和高通量筛选生成底盘菌株。然后修饰 L-缬氨酸生物合成途径和转运模块以提高 L-缬氨酸产量。接下来，研究了与 L-缬氨酸生物合成相关的转录因子。过表达 PdhR 和抑制 RpoS 的表达促进了 L-缬氨酸的合成。最后，通过引入来自运动发酵单胞菌的异源 Entner-Doudoroff（ED）途径增强了 NADPH 的供应。在 5-L 生物反应器中，VAL38 菌株生产 92 g/L L-缬氨酸，葡萄糖得率为 0.34 g/g。该策略为提高 L-缬氨酸及其衍生物的细胞工厂生产性能提供了参考。
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