Bioelectrocatalytic carbon dioxide reduction by an engineered formate dehydrogenase from Thermoanaerobacter kivui
Weisong Liu, Kuncheng Zhang, Jiang Liu, Yuanming Wang, Meng Zhang, Huijuan Cui, Junsong Sun, Lingling Zhang
Abstract
Electrocatalytic carbon dioxide (CO2) reduction by CO2 reductases is a promising approach for biomanufacturing. Among all known biological or chemical catalysts, hydrogen-dependent carbon dioxide reductase from Thermoanaerobacter kivui (TkHDCR) possesses the highest activity toward CO2 reduction. Herein, we engineer TkHDCR to generate an electro-responsive carbon dioxide reductase considering the safety and convenience. To achieve this purpose, a recombinant Escherichia coli TkHDCR overexpression system is established. The formate dehydrogenase is obtained via subunit truncation and rational design, which enables direct electron transfer (DET)-type bioelectrocatalysis with a near-zero overpotential. By applying a constant voltage of −500 mV (vs. SHE) to a mediated electrolytic cell, 22.8 ± 1.6 mM formate is synthesized in 16 h with an average production rate of 7.1 ± 0.5 μmol h−1cm−2, a Faradaic efficiency of 98.9% and a half-cell energy efficiency of 94.4%. This study provides an enzyme candidate for high efficient CO2 reduction and opens up a way to develop paradigm for CO2-based bio-manufacturing. Thermoanaerobacter kivui-drived CO2 reductase (TkHDCR) requires hydrogen as substrate, which can lead to safety issue. Here, the authors engineered TkHDCR into an electro-responsive carbon dioxide reductase to harvest electrons from either an external mediator or a polarized electroactive surface.