Capture of carbon dioxide and hydrogen by engineered Escherichia coli: hydrogen-dependent CO₂ reduction to formate

In times of global climate change and the fear of dwindling resources, we are facing different considerable challenges such as the replacement of fossil fuel-based energy carriers with the coincident maintenance of the increasing energy supply of our growing world population. Therefore, CO₂ capturing and H₂ storing solutions are urgently needed. In this study, we demonstrate the production of a functional and biotechnological interesting enzyme complex from acetogenic bacteria, the hydrogen-dependent CO₂ reductase (HDCR), in the well-known model organism Escherichia coli. We identified the metabolic bottlenecks of the host organisms for the production of the HDCR enzyme complex. Here we show that the recombinant expression of a heterologous enzyme complex transforms E. coli into a whole-cell biocatalyst for hydrogen-driven CO₂ reduction to formate without the need of any external co-factors or endogenous enzymes in the reaction process. This shifts the industrial platform organism E. coli more and more into the focus as biocatalyst for CO₂-capturing and H₂-storage. KEY POINTS: • A functional HDCR enzyme complex was heterologously produced in E. coli. • The metabolic bottlenecks for HDCR production were identified. • HDCR enabled E. coli cell to capture and store H₂ and CO₂ in the form of formate.