Utility of Immobilized Recombinant Carbonic Anhydrase of <i>Bacillus halodurans</i> TSLV1 on the Surface of Modified Iron Magnetic Nanoparticles in Carbon Sequestration

Abstract

Carbonic anhydrase (CA) based conversion of CO 2 to CaCO 3 has been identified as a green and economic strategy to sequester CO 2 from flue gas and industrial emissions. The method is, however, cost-intensive as an efficient immobilization method for reusing the enzyme poses a major challenge. In this investigation, the recombinant carbonic anhydrase of polyextremophilic bacterium Bacillus halodurans TSLV1 (rBhCA) has been immobilized on the surface of modified magnetic (silanized) iron oxide nanoparticles (Si-MNPs). The immobilized rBhCA exhibited improvement in alkalistability and retained significantly high activity at elevated temperatures as compared to the free rBhCA. Furthermore, rBhCA immobilized on Si-MNPs could be easily isolated from the reaction by magnetic separation. After 22 repeated uses, the immobilized rBhCA retained 50% of the initial activity and could be stored for 28 days without any loss in activity. rBhCA-Si-MNPs accelerated the onset of CaCO 3 precipitation over that of the free enzyme, but the amount of CaCO 3 precipitated was not affected, suggesting that the silanized MNPs act as efficient supports for immobilization of CA for utility in CO 2 sequestration.