Integrated multi-barrier attenuation of antibiotic resistance genes by self-elevating ultra-high temperature...

The dissemination of antibiotic resistance genes (ARGs) from livestock manure poses risks to environmental and public health, while conventional composting often shows limited and inconsistent ARG attenuation. Here, we evaluated ARG and mobile genetic element (MGE) dynamics during self-elevating ultra-high temperature composting (sf-HTC) and examined phase-resolved associations among thermal conditions, microbial succession, MGE patterns, and humification indicators using metagenomics, network analysis, and structural equation modeling (SEM). Sf-HTC reduced the absolute abundance of total ARGs and MGEs by 98.86% within 28 days. High-risk ARG classes (tetracycline and sulfonamide-resistance genes) decreased by>94.3%, outperforming traditional composting (TC). The hyperthermophilic phase coincided with the largest decreases in ARGs and with enrichment of thermophilic genera (Calditerricola and Thermophilum) and increased microbial network complexity. SEM further suggested that the thermal regime, reductions in MGEs, and increased humification were major, interrelated pathways statistically associated with ARG reduction (standardized path coefficients: 0.97, -1.41, and 0.78, respectively). Sf-HTC also promoted humic acid accumulation (up to 58.9  g/kg) and more aromatic dissolved organic matter, which was consistent with enhanced immobilization potential for residual ARGs. Overall, our results support a phase-resolved "thermal-biological-chemical" multi-barrier conceptual model for ARG attenuation during sf-HTC and highlight its potential for reducing resistome burdens in agricultural organic wastes.