Hydrogen-fueled CO(2) reduction using oxygen-tolerant oxidoreductases

Hydrogen gas obtained from cheap or sustainable sources has been investigated as an alternative to fossil fuels. By using hydrogenase (H(2)ase) and formate dehydrogenase (FDH), H(2) and CO(2) gases can be converted to formate, which can be conveniently stored and transported. However, developing an enzymatic process that converts H(2) and CO(2) obtained from cheap sources into formate is challenging because even a very small amount of O(2) included in the cheap sources damages most H(2)ases and FDHs. In order to overcome this limitation, we investigated a pair of oxygen-tolerant H(2)ase and FDH. We achieved the cascade reaction between H(2)ase from Ralstonia eutropha H16 (ReSH) and FDH from Rhodobacter capsulatus (RcFDH) to convert H(2) and CO(2) to formate using in situ regeneration of NAD(+)/NADH in the presence of O(2).