The regulation mechanism of bacterial metabolites and cells on the bio-calcium carbonate

The mineralization mechanism of microbially induced calcium carbonate precipitation is vital for its advancement and practical applications. Therefore, this article aims to delve into the influence mechanism of diverse microbial components on the formation of biological calcium carbonate (bio-calcium carbonate) by selecting Bacillus mucilaginosus as the subject of investigation. Initially, the microbial spores and cells are characterized. It is found that after 30 h of cultivation, the bacterial concentration reaches a stable stage, accompanied by a surge in living cells. Moreover, by stripping metabolites from stable bacterial suspension and testing, the Fourier transform infrared and proton nuclear magnetic resonance results indicate that the metabolic components are mainly proteins. Then, the mineralization is carried out in a simulated solution and the X-ray diffraction results show that the bio-calcium carbonate induced by metabolic components and the cells has significant differences in crystal structure. It is also observed through scanning electron microscopy that the bio-calcium carbonate particles are tightly connected by flocculent material. The fluorescence staining results indicate the presence of organic matter on the bio-calcium carbonate surface, thereby indicating the active involvement of microbial cells and their metabolic processes in the formation of these products.