[Spatial and Temporal Differences and Influencing Factors of Mobile Genetic Elements in Urban and Suburban River Sediments in Shijiazhuang City]

Abstract

With the widespread use of antibiotics in medicine and agriculture, the spread of antibiotic resistance genes （ARGs） in the environment has become a serious threat to ecological balance and human health, particularly for its role in facilitating the emergence of multidrug-resistant pathogens. The study of riverine environments as a major transmission route for ARGs and closely related mobile genetic elements （MGEs） is of great importance. MGEs exacerbate the spread of resistance genes by facilitating the horizontal transfer of ARGs in bacterial populations. Although studies have been conducted to explore the interactions between MGEs and ARGs, there is still a relative lack of research on the spatial and temporal differences in the distribution of MGEs in rivers and their drivers. This study selected two rural rivers （with a total of six sampling points） and three urban rivers （with a total of nine sampling points） within Shijiazhuang as research subjects, and sediment samples were collected in December 2020 and April 2021. By employing metagenomic sequencing technology, this study comprehensively compared and analyzed the spatiotemporal distribution characteristics and influencing factors of MGEs in the sediment of urban and rural rivers. The results showed that： ① In December, 1 738 types of MGEs （60572 RPKM） and 1 604 types of MGEs （26916 RPKM） were detected in urban and rural rivers, respectively. In April, 1 790 types of MGEs （74354 RPKM） and 1 631 types of MGEs （32062 RPKM） were detected in urban and rural rivers, respectively. ② The types and abundance of MGEs in urban rivers were greater than those in rural rivers, and the types and abundance of MGEs in April were greater than those in December. ③ ISPa38, IS26, and tnpA were the most significantly different typical MGEs among the rivers in urban and suburban Shijiazhuang. ④ PCoA and NMDS analyses showed significant spatiotemporal differences in MGEs between urban and rural rivers. ⑤ Correlation analysis and co-occurrence results indicated that the abundance of MGEs in urban rivers was significantly positively correlated with antibiotic concentration, industrial enterprises, sewage treatment plants, total population, livestock farming, and aquaculture. In suburban rivers, the abundance of MGEs was mainly significantly positively correlated with antibiotic concentration, livestock farming, aquaculture, and total population. Overall, by comparing the spatiotemporal heterogeneity of MGEs in urban and rural rivers and identifying the main driving factors of MGEs in urban and suburban rivers, this study provides data support for subsequent risk management and control of antibiotic resistance in different rivers.

Keywords: metagenome; mobile genetic elements（MGEs）; rural rivers; socio-economic factors; spatial and temporal distribution; urban rivers.