Induction of calcite precipitation through heightened production of extracellular carbonic anhydrase by CO2 sequestering bacteria

•Bacillus sp. isolated for sequestration of carbon dioxide.•CO2 sequestration by bacterium produced solid carbonate by biomineralization.•Characterization and MALDI-TOF indicated extracellular carbonic anhydrase.•Role of CA indicated eco-friendly product for long term storage. The thermo-alkalotolerant bacterium exhibiting heightened extracellular carbonic anhydrase (CA) activity, survived at 100 mM sodium bicarbonateand 5% gaseous CO2 was identified as Bacillus sp. by 16S rRNA sequencing. Extracellular carbonic anhydrase was purified by ammonium sulfate precipitation, gel filtration chromatography and affinity chromatography with a yield of 46.61% and specific activity of 481.66 U/mg. The size of purified carbonic anhydrase was approximately 28 kDa in SDS-PAGE gel filtration and further their role in calcium carbonate production was correlated. The purified enzyme was stable with half-life of 25.36 min at 90 °C and pH 8. KM and Vmax values of the enzyme were 1.77 mg/mL and 385.69 U/mg respectively. The production of calcite was confirmed by Scanning Electron Microscopy (SEM) analysis, FTIR, and Energy-Dispersive X-ray (EDX) analysis. Carbonic anhydrase and calcite deposition coupled with CO2 fixingbacteria is a significant approach for CO2 sequestration.