Author:
Hao Yanan,Pan Xuewei,Li Guomin,You Jiajia,Zhang Hengwei,Yan Sihan,Xu Meijuan,Rao Zhiming
Abstract
Abstract
Background
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.
Results
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.
Conclusions
The combination of strategies can be applied to the development of microbial platforms that produce l-leucine and its derivatives.
Funder
Postgraduate Research & Practice Innovation Program of Jiangsu Province
the National Natural Science Foundation of China
the Natural Science Foundation of Jiangsu Province
National Key Research and Development Program of China
the National first-class discipline program of Light Industry Technology and Engineering
the Program of Introducing Talents of Discipline to Universities
the project funded by China Postdoctoral Science Foundation
Publisher
Springer Science and Business Media LLC
Subject
Management, Monitoring, Policy and Law,Energy (miscellaneous),Applied Microbiology and Biotechnology,Renewable Energy, Sustainability and the Environment,Biotechnology