Abstract
BACKGROUND: Soil antibiotic resistant genes (ARGs) and mobile genetic elements (MGEs) are associated with agricultural land-use differences. However, assessing the soil antibiotic resistome differences between farmland and pastureland is often limited due to geographically unbalanced sample collection. Leveraging a typical agro-pastoral ecotone in northern China as the study model, we compared the soil microbiome and resistome between 15 adjacent farmland and pastureland pairs using metagenomic sequencing. RESULTS: Results showed that farmland soils harbored higher soil ARG diversity (+ 2.75%), MGE diversity (+ 1.62%) and multidrug resistance-related gene abundance (+ 19.5%) than pastureland. Among them, genes conferring multidrug resistances were dominant in farmland, mainly carried by Pseudomonadota. While, vancomycin-resistant ARGs were dominant in pastureland, mainly carried by Actinomycetota. Metagenome-assembled genomes revealed that sul2 conferring sulfonamide resistance was shared by both Pseudomonadota and Acidobacteriota in farmland together with insertion sequence ISVsa3. Structural equation model analysis integrating with soil geography, pedology and microbiome data showed microbial community and soil properties were identified as major driving factors shaping soil antibiotic resistome diversity in both land-use contexts. MGE diversity showed a clear positive effect on ARG diversity in farmland soils but a minor effect in pastureland. CONCLUSIONS: Together, this study elucidates the shared and distinguished soil antibiotic resistome pattern between farmland and pastureland, extending our understanding of driving factors in agricultural soil ARG contamination.