Disrupting manure-to-soil transmission of antibiotic resistance genes with gamma irradiation and hydrogen peroxide

Abstract

The application of untreated livestock manure poses significant risks for the dissemination of antibiotic resistance genes (ARGs) in agricultural ecosystems, yet conventional pretreatments such as composting or single chemical oxidation often fail to control both ARGs and their mobility. In this study, the synergistic effects of gamma irradiation and hydrogen peroxide were evaluated through integrated metagenomic analysis and soil microcosm experiments, showing that the combined treatment achieved the greatest reductions in both the abundance and diversity of ARGs and mobile genetic elements, outperforming individual treatments. Specifically, in the fertilizer treatment, the ARGs and mobile genetic elements in the combined treatment were reduced by 29.47 % and 24.25 %, respectively, compared with those in the control. The intervention selectively depleted ARG-harboring taxa, including Cellvibrio, Alicyclobacillus, and Chitinophaga, while concurrently suppressing microbial functions critical to ARG dissemination, particularly biofilm formation, membrane transport, and SOS stress response pathways. In soil microcosms, pretreated manure maintained ARG suppression via functional reconstruction, with microbial community shifts identified as the primary driver. These findings highlight a novel dual-action mechanism of gamma irradiation/H₂O₂ co-treatment that not only reduces ARG reservoirs but also disrupts ecological networks underpinning manure-to-soil ARG transmission, offering a mechanistically informed alternative to traditional manure management.