Effects of antibiotics and heavy metals on antibiotic resistance genes and mobile gene elements in agricultural activity

Abstract Soil plays a critical role in retaining antibiotic resistance genes (ARGs) and mobile genetic elements (MGEs), yet few studies have addressed the production of MGEs and the factors influencing their dissemination. In this study, we compared the occurrence and distribution of ARGs and MGEs in agricultural soils and forest soils to assess the impact of agricultural practices by macro-genome sequencing. Our findings indicate that agricultural activities accelerate the production and spread of both ARGs and MGEs, likely driven by increased antibiotic and heavy metal pollution. Notably, the metal elements manganese (Mn) and chromium (Cr) were found at the highest concentrations, while tetracycline and cephalosporin were the most prevalent antibiotics. Seasonal patterns were evident, with the bacterial order Pseudomonadales predominating in summer and Actinomycetota in winter. Moreover, farmland and forest systems exhibited distinct profiles, with farmland soils showing a significantly higher abundance of MGEs—especially during winter. ARGs related to vancomycin resistance and multidrug resistance were prevalent in both environments, and a strong positive correlation was observed between MGEs, such as transposons, and ARGs, such as vanR. In addition, the concentrations of antibiotics like sulfamethoxazole, sulfadimethoxine, and oxytetracycline were significantly correlated with MGEs, while heavy metals including mercury, antimony, and selenium appeared to exert selective pressure on their dissemination.