Electrosynthesis of formate is a promising technology to convert CO2 and electricity from renewable sources into a biocompatible, soluble, non-flammable, and easily storable compound. In the model methanogen Methanococcus maripaludis, uptake of cathodic electrons was shown to proceed indirectly via formation of formate or H2 by undefined, cell-derived enzymes. Here, we identified that the multi-enzyme heterodisulfide reductase supercomplex (Hdr-SC) of M. maripaludis is capable of direct electron uptake and catalyzes rapid H2 and formate formation in electrochemical reactors (-800 mV vs Ag/AgCl) and in Fe(0) corrosion assays. In Fe(0) corrosion assays and electrochemical reactors, purified Hdr-SC primarily catalyzed CO2 reduction to formate with a coulombic efficiency of 90% in the electrochemical cells for 5 days. Thus, this report identified the first enzyme that stably catalyzes the mediator-free electrochemical reduction of CO2 to formate, which can serve as the basis of an enzyme electrode for sustained electrochemical production of formate.
- Direct electron transfer
- Electrochemical synthesis of formate
- Enzyme electrode
- Heterodisulfide reductase
- Microbial electrosynthesis
Lienemann, M., Deutzmann, J. S., Milton, R. D., Sahin, M., & Spormann, A. M. (2018). Mediator-free enzymatic electrosynthesis of formate by the Methanococcus maripaludis heterodisulfide reductase supercomplex. Bioresource Technology, 254, 278-283. https://doi.org/10.1016/j.biortech.2018.01.036