Bacterial enzyme fuels CO₂ hydrogenation

Difficulties with the storage and transport of hydrogen have limited its use as an energy substrate for biofuel production, and, although formate is a more desirable storage material for hydrogen, its production by chemical hydrogenation of CO₂ is technically challenging. However, a study now reports the discovery of a bacterial hydrogen-dependent carbon dioxide reductase (HDCR) from the acetogenic bacterium Acetobacterium woodii that is capable of directly and reversibly catalysing the hydrogenation of CO₂. The enzyme is advantageous for industrial use as it does not need external cofactors and the directionality of the reaction is easily controlled. Furthermore, in addition to CO₂ and hydrogen, syngas (synthesis gas) could be used as a 'greener' substrate for formate production by whole-cell catalysis. Thus, the isolated HDCR enzyme or an A. woodii whole-cell system could be exploited for the storage and production of hydrogen.