The mobility, host, and co-occurrence of antibiotic resistance genes in multi-type pig manure-soil systems: Metagenome assembly analysis.

Antibiotic resistance genes (ARGs) pose significant threats to public health and environmental safety, yet the mobility and hosts of ARGs in animal manure-soil systems remain poorly understood. Here, we evaluated the environmental risks of tilmicosin (TIL) and investigated ARG profiles, mobility, and drivers in pig manure-soil systems using metagenomic assembly. TIL was effectively degraded during aerobic composting and fertilization via hydroxylation, demethylation, and deglycosylation. Notably, the total abundance of ARGs significantly decreased during aerobic composting and fertilization, and manure types affected the distribution and composition of ARGs in fertilized soils. There was a special correlation between the genetic location and type of ARGs. In addition, the results showed co-localization of some specific ARGs and mobile genetic elements (MGEs) (tetA-tetR- transposase; tetR-floR- Tn3 family). A significant correlation was found between Escherichia coli and multiple ARG types, especially multidrug ARGs. Microbial community was the dominant factor driving the variations of ARGs in pig manure-soil systems, followed by MGEs, environmental factors, and antibiotic concentration. This study advances the understanding on the environmental risk assessment of TIL and elucidates the key drivers of ARG dissemination in pig manure-soil systems, providing critical insights and actionable strategies for sustainable livestock management and environmental risk control.