(626m) Biological Conversion of Carbon Dioxide to Chemicals

In recent years, several carbon dioxide capture and storage technologies are being developed. One of the most promising biological carbon dioxide sequestration methods is to use carbonic anhydrase (CA). CA is a zinc-containing metalloenzyme catalyzing the reversible hydration of carbon dioxide (CO₂ + H₂O→HCO₃^-). CA plays an important role for sequestrating carbon dioxide since uncatalyzed interconversion between carbon dioxide and bicarbonate is slow. In the present work, we expressed recombinant CA originated from Neisseria gonorrhoeae in Escherichia coli. We purified recombinant CA with 28 kDa molecular weight including periplasmic signal sequence. The purified recombinant CA showed high biological activity. In addition, calcium carbonate precipitation was successfully observed in carbon dioxide-saturated water solution by addition of calcium chloride. We found that kinetics for forming crystal morphology was much faster than the case without enzyme. Collectively, we could confirm that the possibility of carbon dioxide sequestration using CA and successful conversion of carbon dioxide into calcium carbonate.