Interactions among heavy metals, bacterial communities, mobile genetic elements, and virulence factor genes in shaping antibiotic resistance gene profiles in soils surrounding a 20-year-old landfill.

Municipal solid waste landfills have been recognized as significant reservoirs of antibiotic resistance genes (ARGs). However, the contributions of heavy metals, mobile genetic elements (MGEs), virulence factor genes (VFGs), and bacterial communities to ARG dissemination in surrounding soils remain underexplored. We investigated the spatial distribution of ARGs, MGEs, VFGs, and heavy metals in surface soils within 1 km of a 20-year-old municipal landfill. Cu (32.3 mg/kg) and Cr (70.5 mg/kg) levels were below regulatory thresholds but significantly correlated with ARG abundance (P < 0.05). The relative abundances of ARGs and MGEs fluctuated across sampling points, with no clear decline as distance increased. Structural equation modeling and variation partitioning identified MGEs as the dominant predictors of ARG profiles (standardized coefficient = 0.70, P < 0.001), explaining 26.6 % of the total variance. VFGs contributed 6.4 % and were significantly associated with specific ARG subtypes, suggesting possible co-selection or shared mobility. Bacterial communities indirectly influenced ARG through their association with MGEs. The relative abundance of ARGs peaked at 150 m and 650 m, with quinolone resistance genes being the most abundant. These findings highlight the complex interplay among heavy metals, MGEs, VFGs, and bacterial communities in shaping the dynamics of ARGs, emphasizing the need for integrated monitoring and mitigation strategies in landfill-affected environments.