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Jiang S, Wang D, Wang R, Zhao C, Ma Q, Wu H, Xie X. Reconstructing a recycling and nonauxotroph biosynthetic pathway in Escherichia coli toward highly efficient production of L-citrulline. Metab Eng 2021; 68:220-231. [PMID: 34688880 DOI: 10.1016/j.ymben.2021.10.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Revised: 09/28/2021] [Accepted: 10/19/2021] [Indexed: 10/20/2022]
Abstract
L-citrulline is a high-value amino acid with promising application in medicinal and food industries. Construction of highly efficient microbial cell factories for L-citrulline production is still an open issue due to complex metabolic flux distribution and L-arginine auxotrophy. In this study, we constructed a nonauxotrophic cell factory in Escherichia coli for high-titer L-citrulline production by coupling modular engineering strategies with dynamic pathway regulation. First, the biosynthetic pathway of L-citrulline was enhanced after blockage of the degradation pathway and introduction of heterologous biosynthetic genes from Corynebacterium glutamicum. Specifically, a superior recycling biosynthetic pathway was designed to replace the native linear pathway by deleting native acetylornithine deacetylase. Next, the carbamoyl phosphate and L-glutamate biosynthetic modules, the NADPH generation module, and the efflux module were modified to increase L-citrulline titer further. Finally, a toggle switch that responded to cell density was designed to dynamically control the expression of the argG gene and reconstruct a nonauxotrophic pathway. Without extra supplement of L-arginine during fermentation, the final CIT24 strain produced 82.1 g/L L-citrulline in a 5-L bioreactor with a yield of 0.34 g/g glucose and a productivity of 1.71 g/(L ⋅ h), which were the highest values reported by microbial fermentation. Our study not only demonstrated the successful design of cell factory for high-level L-citrulline production but also provided references of coupling the rational module engineering strategies and dynamic regulation strategies to produce high-value intermediate metabolites.
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Affiliation(s)
- Shuai Jiang
- Key Laboratory of Industrial Fermentation Microbiology of the Ministry of Education, Tianjin University of Science & Technology, Tianjin, 300457, PR China; College of Biotechnology, Tianjin University of Science & Technology, Tianjin, 300457, PR China
| | - Dehu Wang
- Key Laboratory of Industrial Fermentation Microbiology of the Ministry of Education, Tianjin University of Science & Technology, Tianjin, 300457, PR China; College of Biotechnology, Tianjin University of Science & Technology, Tianjin, 300457, PR China
| | - Ruirui Wang
- Key Laboratory of Industrial Fermentation Microbiology of the Ministry of Education, Tianjin University of Science & Technology, Tianjin, 300457, PR China; College of Biotechnology, Tianjin University of Science & Technology, Tianjin, 300457, PR China
| | - Chunguang Zhao
- Ningxia Eppen Biotech Co, Ltd, Ningxia, 750000, PR China
| | - Qian Ma
- Key Laboratory of Industrial Fermentation Microbiology of the Ministry of Education, Tianjin University of Science & Technology, Tianjin, 300457, PR China; College of Biotechnology, Tianjin University of Science & Technology, Tianjin, 300457, PR China
| | - Heyun Wu
- College of Food Science and Engineering, Tianjin University of Science & Technology, Tianjin, 300457, PR China.
| | - Xixian Xie
- Key Laboratory of Industrial Fermentation Microbiology of the Ministry of Education, Tianjin University of Science & Technology, Tianjin, 300457, PR China; College of Biotechnology, Tianjin University of Science & Technology, Tianjin, 300457, PR China.
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