The Mtr Pathway of Shewanella oneidensis MR‐1 Couples Substrate Utilization to Current Production in Escherichia coli


Introducing an electronic interface into Escherichia coli will allow its enormous synthetic biology toolkit to be leveraged in bioelectrochemical applications. While E. coli expressing the Mtr pathway of Shewanella oneidensis MR-1 transfer electrons to an anode, it has remained unclear if this current production alters the intracellular state of E. coli, which is a critical requirement for bioelectronic technologies. Here we address this by characterizing current production in Mtr-expressing E. coli and its effects on cellular viability, substrate consumption, and product generation. We found that cymA-mtr E. coli sustained ~8-fold higher current levels than a control strain. This increased current production did not change E. coli viability or substrate consumption, but it did alter metabolic fluxes. A shift to more oxidized products strongly suggests that the Mtr pathway improves redox balance in E. coli. By demonstrating the Mtr module couples current production to intracellular state, this work establishes Mtr-expressing E. coli as a platform for accelerated development of bioelectronic technologies.