The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 1800# Lihu Road, Wuxi, 214122, People's Republic of China.
Appl Microbiol Biotechnol. 2023 Jun;107(11):3593-3603. doi: 10.1007/s00253-023-12532-1. Epub 2023 Apr 25.
L-arginine (L-Arg) is a semi-essential amino acid with many important physiological functions. However, achieving efficient manufacture of L-Arg on an industrial scale using Escherichia coli (E. coli) remains a major challenge. In previous studies, we constructed a strain of E. coli A7, which had good L-Arg production capacity. In this study, E. coli A7 was further modified, and E. coli A21 with more efficient L-Arg production capacity was obtained. Firstly, we reduced the acetate accumulation of strain A7 by weakening the poxB gene and overexpressing acs gene. Secondly, we improved the L-Arg transport efficiency of strains by overexpressing the lysE gene from Corynebacterium glutamicum (C. glutamicum). Finally, we enhanced the supplies of precursors for the synthesis of L-Arg and optimized the supplies of cofactor NADPH and energy ATP in strain. After fermentation in a 5-L bioreactor, the L-Arg titer of strain A21 was found to be 89.7 g/L. The productivity was 1.495 g/(L·h) and the glucose yield was 0.377 g/g. Our study further narrowed the titer gap between E. coli and C. glutamicum in the synthesis of L-Arg. In all recent studies on the L-Arg production by E. coli, this was the highest titer recorded. In conclusion, our study further promotes the efficient mass synthesis of L-Arg by E. coli. KEY POINTS: • The acetate accumulation of starting strain A7 was decreased. • Overexpression of gene lysE of C. glutamicum enhanced L-Arg transport in strain A10. • Enhance the supplies of precursors for the synthesis of L-Arg and optimize the supplies of cofactor NADPH and energy ATP. Finally, Strain A21 was detected to have an L-Arg titer of 89.7 g/L in a 5-L bioreactor.
L-精氨酸（L-Arg）是一种半必需氨基酸，具有许多重要的生理功能。然而，利用大肠杆菌（E. coli）在工业规模上高效生产 L-Arg 仍然是一个主要挑战。在以前的研究中，我们构建了一株具有良好 L-Arg 生产能力的大肠杆菌 A7 菌株。在本研究中，我们进一步对大肠杆菌 A7 进行了修饰，获得了具有更高 L-Arg 生产能力的大肠杆菌 A21 菌株。首先，我们通过削弱 poxB 基因并过表达 acs 基因来减少菌株 A7 的乙酸积累。其次，我们通过过表达来自谷氨酸棒杆菌（C. glutamicum）的 lysE 基因来提高菌株的 L-Arg 转运效率。最后，我们增强了 L-Arg 合成的前体供应，并优化了菌株中辅酶 NADPH 和能量 ATP 的供应。在 5-L 生物反应器中发酵后，发现菌株 A21 的 L-Arg 浓度为 89.7 g/L。产率为 1.495 g/（L·h），葡萄糖得率为 0.377 g/g。我们的研究进一步缩小了大肠杆菌和谷氨酸棒杆菌在 L-Arg 合成中的浓度差距。在所有最近关于大肠杆菌生产 L-Arg 的研究中，这是记录到的最高浓度。总之，我们的研究进一步促进了大肠杆菌高效大规模合成 L-Arg。关键点：•降低起始菌株 A7 的乙酸积累。•过表达 C. glutamicum 的基因 lysE 增强了菌株 A10 中的 L-Arg 转运。•增强 L-Arg 合成的前体供应并优化辅酶 NADPH 和能量 ATP 的供应。最后，在 5-L 生物反应器中检测到菌株 A21 的 L-Arg 浓度为 89.7 g/L。
