Fate and Risk of Florfenicol, Thiamphenicol, and Antibiotic Resistance Genes During Composting of Swine Manure

Livestock manure is considered an important source of antibiotic resistance genes (ARGs) spreading to the environment, posing a potential threat to human health. Here, we investigated the dissipation of florfenicol (FF) and thiamphenicol (TAP), and their effects on bacterial community, mobile genetic elements (MGEs), and ARGs during composting. The results indicated that FF and TAP dissipated rapidly in compost, with half-life values of 5.1 and 1.6 d, respectively. The FF and TAP residues in the manure may have a negative influence on the physicochemical factors of the compost while could reduce the elimination of ARGs and MGEs during composting. Proteobacteria and Firmicutes were the dominant bacterial communities and important potential pathogen hosts carrying ARGs. The predicted concentration of FF in soil (≥100μg/kg) indicates potential risk to the natural environment. Further studies are needed to investigate the best environmental conditions to achieve more comprehensive elimination of ARGs and MGEs during composting.