Improvement of succinate production by overexpression of a cyanobacterial carbonic anhydrase in Escherichia coli |
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Authors: | Dan Wang Qiang Li Wangliang Li Jianmin Xing Zhiguo Su |
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Affiliation: | aNational Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China;bGraduate University of Chinese Academy of Sciences, Beijing 100049, China |
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Abstract: | Succinate fermentation was investigated in Escherichia coli strains overexpressing cyanobacterium Anabaena sp. 7120 ecaA gene encoding carbonic anhydrase (CA). In strain BL21 (DE3) bearing ecaA, the activity of CA was 21.8 U mg−1 protein, whereas non-detectable CA activity was observed in the control strain. Meanwhile, the activity of phosphoenolpyruvate carboxylase (PEPC) increased from 0.2 U mg−1 protein to 1.13 U mg−1 protein. The recombinant bearing ecaA reached a succinate yield of 0.39 mol mol−1 glucose at the end of the fermentation. It was 2.1-fold higher than that of control strain which was just 0.19 mol mol−1 glucose. EcaA gene was also introduced into E. coli DC1515, which was deficient in glucose phosphotransferase, lactate dehydrogenase and pyruvate:formate lyase. Succinate yield can be further increased to 1.26 mol mol−1 glucose. It could be concluded that the enhancement of the supply of HCO3− in vivo by ecaA overexpression is an effective strategy for the improvement of succinate production in E. coli. |
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Keywords: | Succinate Escherichia coli Carbonic anhydrase (CA) Bicarbonate Carbon dioxide |
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