Region-Specific Bacterial Carbonic Anhydrase for Biomimetic Sequestration of Carbon Dioxide

Biomimetic carbonic anhydrase (CA)-based CO2 sequestration for its conversion into carbonate is being pursued all across the globe. For this purpose, partially purified enzyme CA has been isolated from three different microorganisms, including Bacillus pumilus, Pseudomonas fragi, and Micrococcus lylae. Proof of concept has been established for the carbonation reaction. The carbonate has been characterized using various tools, such as X-ray diffraction (XRD) and scanning electron microscopy (SEM), which confirms the calcite phase of calcium carbonate. The formation of carbonate has been quantified using gas chromatography. Partially purified CA isolated from P. fragi shows a significantly high CO2 sequestration capacity of 27.33 mg of CaCO3/mg of CA in 15 min compared to B. pumilus and M. lylae. The enzyme has been immobilized on surfactant-modified silylated chitosan. The immobilized enzyme shows improved storage stability and retained 50% initial activity up to 30 days