Antibiotic Resistome and its Driving Factors in an Urban River in Northern China

Abstract

Urban rivers dynamically influenced by anthropogenic activities are considered as a vital reservoir of antibiotic resistance genes (ARGs). Knowledge on resistome profiles in urban rivers allows better understanding of ARG dissemination, but has not been well explored. Here, a total of 198 ARGs and 12 mobile genetic elements (MGEs) were profiled in water and sediments from the Chaobai river, Beijing. The ARGs with abundances of 1.01×10 6 –3.34×10 8 copies/L in water and 2.92×10 6 –4.58×10 9 copies/g in sediments, dominated by beta-lactamase, displayed a significant seasonal variation. Significant linear correlations between the total abundances of ARGs and MGEs were oberved in the two matrices ( p < 0.01). Environmental factors and antibiotics were the main contributors to their variations, and explained 55‒80% and 27‒67% of the total variation in ARGs and MGEs, respectively. Environmental factors affected ARGs directly or indirectly through antibiotics and MGEs sequentially in water, and influenced ARGs indirectly via MGEs or antibiotics and MGEs sequentially in sediments. Moreover, MGEs, particularly transposase genes, were the main drivers of ARG dissemination in both water and sediments. Overall, this study provides a comprehensive understanding of the driving factors for the dissemination of ARGs in an urban river.

Keywords: Urban river, Antibiotic resistance genes, Driving factors, Mobile genetic elements