Scaling down recombinant carbonic anhydrase isolation with immobilized metal ion chromatography (IMAC): Harnessing enzymatic carbon dioxide capture and mineralization

Background: Human activities have led to increased atmospheric CO2 2 levels, raising concerns about climate change. Carbonic anhydrase (CA) enzymes show promise for transforming CO2 2 into valuable products like calcium carbonate (CaCO3) 3 ) through mineralization. Purifying and immobilizing CA enzymes on nanofiber membranes enhances their catalytic activity, enabling efficient CO2 2 conversion and mineralization. Methods: Recombinant CA was purified using immobilized metal affinity chromatography (IMAC), optimizing pH, biomass concentration, flow rate, and loading volume for maximum efficiency. The CA enzyme was then immobilized onto a weak ion exchange nanofiber membrane functionalized with AEA-COOH to create the CA- modified membrane (AEA-COOH-CA), enhancing CO2 2 conversion and CaCO3 3 mineralization. Significant findings: Optimal purification conditions (pH 7, 1 % biomass, 0.1 mL/min flow rate, 1.0 mL loading volume) were determined using IMAC. The CA-modified membrane effectively converted CO2 2 and mineralized CaCO3, 3 , demonstrating the potential for environmental CO2 2 sequestration. The immobilized CA activities of the AEA-COOH-CA nanofiber membranes exhibited 473.42 WAU/g-membrane, corresponding to 7.10 WAU per membrane piece. The CaCO3 3 precipitation reached 83.90 mg, with a precipitation efficiency of 11.82 mg CaCO3/ 3 / WAU. These findings underscore the promise of enzymatic carbon capture using CA-modified membranes, offering a sustainable solution for greenhouse gas mitigation.