Application of Microporous Bio-Gravel for Microecological Remediation of Degraded Mine Soils
Mining activities cause severe soil degradation and microbial diversity loss, impeding ecological restoration. This study evaluated the effects of a novel soil amendment, microporous bio-gravel (MBG), on bacterial and fungal community structure and function in degraded soil from the Baiyinhua open-pit mine, Inner Mongolia. A pot experiment with four MBG-to-soil volume ratios (CK, L=1:3, M=1:2, H=1:1) was conducted, with a simplified plant community and uniform fertilization. After 180 days, soil samples were analyzed via high-throughput sequencing and bioinformatics. Results showed that the medium ratio (M) significantly increased fungal Shannon index and evenness, while the high ratio (H) negatively affected bacterial communities. At phylum and genus levels, MBG promoted enrichment of Cyanobacteria and specific functional groups (e.g., nitrogen-fixing bacteria, Bacillus). Co-occurrence network analysis revealed peak complexity, modularity, and average degree in bacterial and fungal networks under the M treatment. Functional prediction indicated significant enrichment of pathways related to lipopolysaccharide biosynthesis, nitrotoluene degradation, and plant-pathogen interactions, alongside increased abundance of saprotrophic and ectomycorrhizal fungi. Mantel and VPA analyses showed that MBG indirectly regulated microbial community structure by improving soil physicochemical properties and plant traits, with stronger effects on fungi than bacteria. In conclusion, MBG optimizes the soil microhabitat and plant-soil-microbe interactions, modulating microbial diversity, network complexity, and functional potential. The medium ratio (1:2) was most effective, demonstrating potential for ecological restoration of degraded mine soils.