Fates of antibiotic resistance genes in a distributed swine wastewater treatment plant.

This study explores the prevalence, emission, and reduction of five ARGs (sulI, tetA, mphB, qnrD, and mcr-1) and integron (intI) through a distributed swine wastewater purification facility and the effluent-receiving environment. Typical metal resistance genes (MRGs), pathogenic bacterial indicators, the bacterial community, and wastewater properties were also explored to determine their effects on the fates of ARGs. Results indicated that the purification process could hardly effectively remove ARGs' prevalence. 3.1 × 10 -7.1 × 10  copies/L were present after purification, and 4%-57% of them persisted in the subsequent creek and adjacent soil. 16S rRNA sequencing suggested that the discharge of wastewater significantly changed the bacterial community in receiving creek and soil. Molecular ecological networks analysis detected the wide co-occurrence among ARGs, MRGs, and PBGs, which could further facilitate the propagation of antibiotic resistance. ARG incidence and specific bacterial genera were closely correlated, suggesting an extensive hosting relationship. Redundancy analyses showed wastewater organics and nutrients showed positive correlation to most ARGs' abundance, but negatively correlated to their relative abundance. PRACTITIONER POINTS: Fate of five ARGs and intI was studied in a swine wastewater treatment system. The treatment process could not effectively reduce ARGs' abundance. ARGs and pathogens in wastewater were transferred to the receiving creek and soil. The network analysis found wide co-occurrence among ARGs, metal resistance genes, and pathogens. Wastewater nutrients positively correlated to ARG's abundance but negatively correlated to their relative abundance.