Engineering an electroactive Escherichia coli for the microbial electrosynthesis of succinate from glucose and CO2

TLDR

Electrochemical energy is essential for biosynthetic reduction of substrates such as CO₂, yet prior microbial electrosynthesis mainly employed naturally electroactive microbes that produced non‑specific products. The authors aimed to engineer an electroactive E. coli strain capable of producing succinate from glucose and CO₂ by harnessing electrical energy. They introduced the Shewanella oneidensis MR‑1 electron‑transfer genes mtrABC, fccA and cymA into E.

Abstract

Electrochemical energy is a key factor of biosynthesis, and is necessary for the reduction or assimilation of substrates such as CO2. Previous microbial electrosynthesis (MES) research mainly utilized naturally electroactive microbes to generate non-specific products. In this research, an electroactive succinate-producing cell factory was engineered in E. coli T110(pMtrABC, pFccA-CymA) by expressing mtrABC, fccA and cymA from Shewanella oneidensis MR-1, which can utilize electricity to reduce fumarate. The electroactive T110 strain was further improved by incorporating a carbon concentration mechanism (CCM). This strain was fermented in an MES system with neutral red as the electron carrier and supplemented with HCO3+, which produced a succinate yield of 1.10 mol/mol glucose—a 1.6-fold improvement over the parent strain T110. The strain T110(pMtrABC, pFccA-CymA, pBTCA) is to our best knowledge the first electroactive microbial cell factory engineered to directly utilize electricity for the production of a specific product. Due to the versatility of the E. coli platform, this pioneering research opens the possibility of engineering various other cell factories to utilize electricity for bioproduction.