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

Abstract

Background

Human activities have led to increased atmospheric CO₂ levels, raising concerns about climate change. Carbonic anhydrase (CA) enzymes show promise for transforming CO₂ into valuable products like calcium carbonate (CaCO₃) through mineralization. Purifying and immobilizing CA enzymes on nanofiber membranes enhances their catalytic activity, enabling efficient CO₂ 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 conversion and CaCO₃ 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 and mineralized CaCO₃, demonstrating the potential for environmental CO₂ 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 precipitation reached 83.90 mg, with a precipitation efficiency of 11.82 mg CaCO₃/WAU. These findings underscore the promise of enzymatic carbon capture using CA-modified membranes, offering a sustainable solution for greenhouse gas mitigation.