H 2 -driven reduction of CO 2 to formate using bacterial plasma membranes.

Bacterial membranes shield the intracellular compartment by selectively allowing unwanted substances to enter in, which in turn reduces overall catalytic efficiency. This report presents a model system using the isolated plasma membranes of Citrobacter sp. S-77 that harbor oxygen-stable [NiFe]hydrogenase and [Mo]formate dehydrogenase, which are integrated into a natural catalytic nanodevice through an electron transfer relay. This naturally occurring nanodevice exhibited selectivity and efficiency in catalyzing the H ₂ -driven conversion of CO ₂ to formate with the rate of 817 mmol·L ^-1 ·g _protein ^-1 ·h ^-1 under mild conditions of 30 °C, pH 7.0, and 0.1 MPa. When the isolated plasma membranes of Citrobacter sp. S-77 was immobilized with multi-walled carbon nanotubes and encapsulated in hydrogel beads of gellan-gum cross-linked with calcium ions, the catalyst for formate production remained stable over 10 repeated uses. This paper reports the first case of efficient and selective formate production from H ₂ and CO ₂ using bacterial plasma membranes.
Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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