Deciphering the antibiotic resistome and microbial community in municipal wastewater treatment plants at different elevations in eastern and western China

Abstract

Antibiotic resistance genes (ARGs) as emerging environmental contaminants pose severe global risks to public health and ecosystems. Municipal wastewater treatment plants (WWTPs) are crucial transmitters for the dissemination and propagation of ARGs into receiving water bodies via mobile genetic elements (MGEs). However, the comprehensive and deep deciphering of the diversity, abundance, and potential hosts of ARGs in two distinct altitudinal WWTPs is scarce. In this work, we revealed the elevational distribution characteristics of the resistance genes and microbial community of six WWTPs from two distinct geographical zones: a low−elevation (LE) region (Shandong, 10–22 m above sea level) and a high−elevation (HE) region (Gansu, 1,520–1,708 m above sea level). Significant elevational variations in the diversity and relative abundance of resistance genes were observed. Wastewater treatment could significantly reduce the concentrations of ARGs and MGEs by about 1–2 and 2–3 orders of magnitude, respectively. However, above 69.95% of resistance genes were enriched in effluent. In particular, 24 ARG subtype, 3 MGE subtypes, and 59 bacterial genera were persistent in all samples. More potential hosts for ARGs in LE region and more abundant human gut microbiota in HE region were identified. This work provides helpful information for controlling the spread of ARGs for their management and assessment, thereby mitigating the risks of ARGs in WWTPs.