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Enhancing the supply of oxaloacetate for l-glutamate production by pyc overexpression in different Corynebacterium glutamicum |
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| Authors: | Xuan Guo Jing Wang Xixian Xie Qingyang Xu Chenglin Zhang Ning Chen |
| Institution: | 1. National and Local United Engineering Lab of Metabolic Control Fermentation Technology, Tianjin University of Science and Technology, Tianjin, 300457, China 2. Tianjin Engineering Lab of Efficient and Green Amino Acid Manufacture, Tianjin University of Science and Technology, Tianjin, 300457, China 3. Key Laboratory of Industrial Microbiology of Education Ministry, Tianjin University of Science and Technology, Tianjin, 300457, China 4. Metabolic Engineering Laboratory, College of Biotechnology, Tianjin University of Science and Technology, No. 29, 13 Main Street, Tianjin Economic and Technological Development Area, Tianjin, 300457, People’s Republic of China |
| Abstract: | During l-glutamate production, phosphoenolpyruvate carboxylase and pyruvate carboxylase (PCx) play important roles in supplying oxaloacetate to the tricarboxylic acid cycle. To explore the significance of PCx for l-glutamate overproduction, the pyc gene encoding PCx was amplified in Corynebacterium glutamicum GDK-9 triggered by biotin limitation and CN1021 triggered by a temperature shock, respectively. In the fed-batch cultures, GDK-9pXMJ19pyc exhibited 7.4 % lower l-alanine excretion and no improved l-glutamate production. In contrast, CN1021pXMJ19pyc finally exhibited 13 % lower l-alanine excretion and identical l-glutamate production, however, 8.5 % higher l-glutamate production was detected during a short period of the fermentation. It was indicated that pyc overexpression in l-glutamate producer strains, especially CN1021, increased the supply of oxaloacetate for l-glutamate synthesis and decreased byproduct excretion at the pyruvate node. |
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