Electrical-biological hybrid system for CO reduction.

Here we have developed an electrochemical-biological hybrid system to fix CO. Natural biological CO fixation processes are relatively slow. To increase the speed of fixation we applied electrocatalysts to reduce CO to formate. We chose a user-friendly organism, Escherichia coli, as host. Overall, the newly constructed CO and formate fixation pathway converts two formate and one CO to one pyruvate via glycine and L-serine in E. coli. First, one formate and one CO are converted to one glycine. Second, L-serine is produced from one glycine and one formate. Lastly, L-serine is converted to pyruvate. E. coli's genetic tractability allowed us to balance various parameters of the pathway. The carbon flux of the pathway was sufficient to compensate L-serine auxotrophy in the strain. In total, we integrated both electrocatalysis and biological systems into a single pot to support E. coli growth with CO and electricity. Results show promise for using this hybrid system for chemical production from CO and electricity.