Microbial-induced carbon dioxide (CO2) mineralization: Investigating the bio-mineralization chemistry process and the potential of storage in sandstone reservoir

Mineralization represents a crucial technological approach for carbon sequestration. In this study, a strain ZL-03 with carbon mineralization ability was screened and identified as Bacillus mucilaginosus Krassilnikov by 16SrDNA. The growth morphology, physicochemical properties, and metabolic products of the strain under CO2 stress were comprehensively investigated by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Furthermore, employing the highly precise 13CO2 isotope, the chemical pathway of microbial extracellular induction for CO2 sequestration and biomineralization was elucidated. The results indicate that strain ZL-03 exhibits increased carbonic anhydrase (CA) activity and secretes extracellular organic matrix containing electron-donating functional groups such as -OH and -COOH under CO2 stress. The study reveals two pathways for strain ZL-03's extracellular mineralization of CO2:the secretion of CA promotes the dissolution and ionization of CO2 into HCO3−, which then combines with Ca2+ to form minerals; the microbial secretion of extracellular organic matrix complexes with Ca2+ in the solution to form a mineralization matrix, and CO2 reacts with the mineralization matrix (metal complex) to generate amorphous calcium carbonate (CaCO3·H2O). Moreover, the research results reveal that the selected microorganisms can reduce reservoir permeability by 63.8%.