Soil antimony–microbe interactions in an abandoned antimony mine in southern China

Abstract

Soil contamination resulting from antimony (Sb) mining activities poses a substantial environmental risk in karst ecosystems. Understanding microbially mediated Sb transformation mechanisms is critical for advancing eco-friendly remediation technologies. The structural and functional responses of soil microbial communities were systematically investigated across three distinct areas (mining, smelting, and control) in typical Sb mining regions of Southwest China. Integrated geochemical and multi-omics analyses revealed pronounced Sb contamination gradients. Total Sb (Sb_tot) concentrations followed the order: smelting area (8231.97 ± 6875.22) > mining area (735.03 ± 367.21 mg/kg) > control area (69.11 ± 0.47 mg/kg). Microbial community profiling indicated bacterial dominance (97.6 % relative abundance), followed by archaea (2.0 %) and fungi (0.4 %). Notably, eight bacterial genera (Achromobacter, Sphingomonas, Thermomonas, Janibacter, Stenotrophomonas, Arenimonas, Bifidobacterium, and Halothiobacillus) exhibited significant positive correlations (p < 0.01) with Sb_tot concentrations, suggesting their resistance to Sb. Functional annotation revealed critical associations between Sb biotransformation and microbial metabolic pathways, particularly sulfur redox cycling (sulfur oxidation: soxABXYZ; sulfate reduction: dsrAB) and nitrogen metabolism (nitrate reduction: narGHI). Co-occurrence network analysis indicated synergistic relationships between Sb-resistant microbes and elemental-cycling functional genes. Collectively, the results suggest that microbial Sb transformation in karst soils involves sulfur-assisted electron transfer and nitrate-dependent Sb oxidation. This study provides insight into the biogeochemical drivers of Sb fate in contaminated environments and establishes a conceptual framework for the development of microbiome-based remediation strategies suitable for Sb-polluted karst regions.