Domestication of Sporosarcina pasteurii and enhanced mechanical properties of gangue microbial backfill

To enhance the cementation effect of microbial-induced carbonate precipitation (MICP) on coal gangue, a gradient adaptive domestication experiment of Sporosarcina pasteurii was conducted in the gangue slurry environment. The domestication effect was comprehensively evaluated through mechanical tests and microstructural analyses of gangue microbial backfill (GMB) materials. The results show: (1) a ten-gradient domestication method was selected to domesticate Sporosarcina pasteurii . The urease activity is improved by 828% through domestication at the maximum gangue leachate concentration of 30% by volume. (2) The effects on the mechanical properties of the cementation solution concentration, the bacterial suspension to cementation solution ratio, and the solid mass concentration were studied. Microbial domestication can significantly improve the mechanical performance of GMB materials by up to 30.19%. The maximum uniaxial compressive strength of the domesticated GMB reaches 1.68 MPa. (3) The calcium carbonate produced by Sporosarcina pasteurii is predominantly calcite, which functions as a binder between coal gangue particles. Domesticated Sporosarcina pasteurii generates more calcite during the MICP process, thereby contributing to higher strength.