Coutilization of glucose and acetate for the production of pyruvate by engineered Escherichia coli

Abstract

Escherichia coli normally produces acetate during mixed-acid fermentation under anaerobic condition, or excretes acetate during rapid consumption of glucose even in the presence of adequate oxygen. This overflow metabolism hinders cell growth rate and decreases the performance of microbial fermentation processes. In this study, we reported the rationally engineering of E. coli central metabolic pathways for the production of pyruvate using glucose and acetate as combined carbon sources. The inactivation of pyruvate-degrading genes including poxB, pflB, and aceEF generated an E. coli strain which can assimilate glucose/acetate at the same time and accumulate lactate/pyruvate as end products. Additional gene deletions of ldhA and mgsA completely eliminated lactate formation. The engineered strain produced 9.61 g/L pyruvate from 10.27 g/L glucose and 2.00 g/L acetate in shake flask cultivations using minimal medium. Our proposed metabolic engineering strategies illustrate the feasibility for efficient production of glucose-derived chemicals through the addition of acetate as assistant carbon source to support cell growth.