Effects of copper and cadmium stress on resistance genes in farmland soil

Current farmland soils are increasingly affected by contamination from antibiotic resistance genes (ARGs) and heavy metals, with the evolution of microbial antibiotic resistance potentially influenced by metal stress. The distribution effects of antibiotic resistance genes (ARGs) in farmland soils under cadmium (Cd) and copper (Cu) combined pollution remain unclear.
Results
This study aims to: Results show that Cu and Cd exhibit significant dominant effects on Bacitracin, fosfomycin, sulfonamide, trimethoprim-beta-lactam, polymyxin, tetracycline, trimethoprim, and vancomycin. Interactions between Cd/Cu and fosmidomycin, MLS, multidrug resistance, sulfonamide, and vancomycin abundance are significant. Co-occurrence network analysis identifies Pseudomonadota, Actinobacteria, and Acidobacteria as primary potential host groups for ARGs. Structural equation modeling analysis further demonstrates that Cd exhibits more pronounced effects on ARGs abundance compared to Cu. Contrary to previous studies, this research reveals that bacterial community αdiversity and mobile genetic elements (MGEs) contribute relatively minimally to ARGs abundance, while mobile genetic regions (MRGs) demonstrate a highly significant positive correlation with ARGs.These findings hold substantial implications for assessing potential ecological risks in soil metal pollution and provide new insights into the co-selection mechanisms between Cd and Cu in shaping ARGs dynamics.