Newly explored formate dehydrogenases from Clostridium species catalyze carbon dioxide to formate

With concerns over global warming and climate change, many efforts have been devoted to mitigate atmospheric CO₂ level. As a CO₂ utilization strategy, formate dehydrogenase (FDH) from Clostridium species were explored to discover O₂-tolerant and efficient FDHs that can catalyze CO₂ to formate (i.e. CO₂ reductase). With FDH from Clostridium ljungdahlii (ClFDH) that plays as a CO₂ reductase previously reported as the reference, FDH from C.autoethanogenum (CaFDH), C. coskatii (CcFDH), and C. ragsdalei (CrFDH) were newly discovered via genome-mining. The FDHs were expressed in Escherichia coli and the recombinant FDHs successfully catalyzed CO₂ reduction with a specific activity of 15 U g^-1-CaFDH, 17 U g^-1-CcFDH, and 8.7 U g^-1-CrFDH. Interestingly, all FDHs newly discovered retain their catalytic activity under aerobic condition, although Clostridium species are strict anaerobe. The results discussed herein can contribute to biocatalytic CO₂ utilization.