Improvement of succinate production by overexpression of a cyanobacterial carbonic anhydrase in Escherichia coli

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) in glucose at the end of the fermentation. It was 21-fold higher than that of con trot 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 call 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 all effective strategy for the Improvement of succinate production in E. Coli. (C) 2009 Elsevier Inc All rights reserved.