Hao Yanan, Pan Xuewei, Li Guomin, You Jiajia, Zhang Hengwei, Yan Sihan, Xu Meijuan, Rao Zhiming
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.
Yixing Institute of Food and Biotechnology Co., Ltd, Yixing, 214200, China.
Biotechnol Biofuels Bioprod. 2023 Sep 29;16(1):145. doi: 10.1186/s13068-023-02397-x.
L-Leucine is a high-value amino acid with promising applications in the medicine and feed industries. However, the complex metabolic network and intracellular redox imbalance in fermentative microbes limit their efficient biosynthesis of L-leucine.
In this study, we applied rational metabolic engineering and a dynamic regulation strategy to construct a plasmid-free, non-auxotrophic Escherichia coli strain that overproduces L-leucine. First, the L-leucine biosynthesis pathway was strengthened through multi-step rational metabolic engineering. Then, a cooperative cofactor utilization strategy was designed to ensure redox balance for L-leucine production. Finally, to further improve the L-leucine yield, a toggle switch for dynamically controlling sucAB expression was applied to accurately regulate the tricarboxylic acid cycle and the carbon flux toward L-leucine biosynthesis. Strain LEU27 produced up to 55 g/L of L-leucine, with a yield of 0.23 g/g glucose.
The combination of strategies can be applied to the development of microbial platforms that produce L-leucine and its derivatives.
L-亮氨酸是一种高价值氨基酸，在医药和饲料工业中具有广阔的应用前景。然而，发酵微生物中复杂的代谢网络和细胞内氧化还原失衡限制了它们高效生物合成L-亮氨酸。
在本研究中，我们应用合理的代谢工程和动态调控策略构建了一种无质粒、非营养缺陷型的过量生产L-亮氨酸的大肠杆菌菌株。首先，通过多步合理的代谢工程强化了L-亮氨酸生物合成途径。然后，设计了一种协同辅因子利用策略，以确保L-亮氨酸生产过程中的氧化还原平衡。最后，为了进一步提高L-亮氨酸产量，应用了一个用于动态控制sucAB表达的切换开关，以精确调节三羧酸循环和通向L-亮氨酸生物合成的碳通量。菌株LEU27产生了高达55 g/L的L-亮氨酸，葡萄糖产率为0.23 g/g。
这些策略的组合可应用于开发生产L-亮氨酸及其衍生物的微生物平台。
