Effects of microbially induced calcium carbonate precipitation on soil bacterial communities, predictions of phenotypic and functional characteristics

Microbially induced carbonate precipitation (MICP) is widely applied in soil stabilization, yet its long-term impacts on bacterial community structure and function remain unclear. This study investigated the regulatory mechanisms of MICP on soil physicochemical properties and microbial communities by spraying Sporosarcina pasteurii and cementation solutions (urea + CaCl₂) combined with high-throughput sequencing, phenotypic prediction, and genomic functional analysis. The results demonstrated that MICP significantly increased soil pH (from 7.62 to 7.94), alkali-hydrolyzable nitrogen (AHN: from 67 to 1 603 mg·kg⁻¹), and chloride ion concentration (from 377 to 26 679 mg·kg⁻¹), while inducing calcium carbonate deposition. The Shannon diversity index decreased significantly, and microbial community structure converged, with the relative abundances of Firmicutes and Bacteroidota increasing from 3.31% and 1.68% to 12.73% and 6.78%, respectively, while Proteobacteria and Actinobacteriota decreased from 48.56% and 25.53% to 41.61% and 19.17%. Core functional taxa, including Lysobacter and Sporosarcina, were significantly enriched, driven by biofilm formation, urease activity, and salt-alkali tolerance gene expression. Redundancy analysis and network topology revealed that Ca²⁺, AHN, and pH formed a driving framework for community differentiation, explaining 66.51% of the variation. Functional predictions indicated suppressed core metabolic pathways (e.g., DNA replication and energy metabolism, reduced by 15%–35%) but enhanced biofilm formation and stress-resistant phenotypes in the MICP group. This study demonstrates that MICP screens for stress-resistant functional bacteria through a high-calcium, high-chloride, and alkaline environment, but it may sacrifice the diversity of soil ecological functions. These findings provide a theoretical basis for ecological risk assessment and process optimization of MICP technology.