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

Cu and Cd exerted significant main effects on bacitracin, fosfomycin, sulfonamide, trimethoprim-b-lactam, polymyxin, tetracycline, trimethoprim, and vancomycin resistance genes. Interactions between Cd/Cu and fosmidomycin, Macrolide-Lincosamide Streptogramin, multidrug resistance, sulfonamide, and vancomycin abundance are significant. Co-occurrence network analysis identifies Pseudomonadota, Actinobacteriota, and Acidobacteriota 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. In contrast to some previous studies, bacterial alpha-diversity and mobile genetic elements did not act as primary drivers of ARGs variation, whereas metal resistance genes showed a strong positive association with ARGs abundance.