Continuous Modular Biomimetic Utilization of Carbon Dioxide toward Multi- and Chemoenzymatic Systems

This study shows the preparation and application of modular biomimetic carbon dioxide utilization of multi- and chemoenzymatic systems for long-term stable continuous operation. The system is assembled by enzyme immobilization on the silica-shell surface of the hybrid microbeads forming stabilized carbonic anhydrase (CA) and phosphoenolpyruvate carboxylase (PEPCase) microbeads, respectively. The CA and PEPCase microbeads were very stable, preserving 85% of their initial activity over more than 30 days. In addition, both hybrid microbeads were repeatedly used successfully for more than 20 cycles of reaction, and they still remained active with facile magnetic separability at room temperature. In addition, the CA and PEPCase microbeads were employed within a modular enzyme reactor system to show its long-term and stable use in the continuous and/or simultaneous production of oxaloacetate (OAA) and CaCO₃ from a continuously supplied CO₂ solution. It was found that the production of OAA and CaCO₃ was stable for more than 24 h and 6 days, respectively. This is a demonstration study of both repeated-batch and continuous modes for stable CO₂ utilization and sequestration biomimetically by using stabilized multi- and chemoenzymatic modular catalysis systems.