Deciphering the mechanisms shaping the antibiotic resistance genes in the vertical plastisphere in hyporheic zone under hydrological exchange

Yufang Chen; Zhenhua Yan; Qiyi Yuan; Lan Ma; Min Wang; Peng Zhang; Runren Jiang; Guanghua Lu; Saiyu Yuan; Karina Yew-Hoong Gin

doi:10.1016/j.watres.2026.125659

Deciphering the mechanisms shaping the antibiotic resistance genes in the vertical plastisphere in hyporheic zone under hydrological exchange

Water Res. 2026 Jun 1:297:125659. doi: 10.1016/j.watres.2026.125659. Epub 2026 Feb 28.

Authors

Yufang Chen¹, Zhenhua Yan², Qiyi Yuan³, Lan Ma⁴, Min Wang⁴, Peng Zhang⁴, Runren Jiang⁴, Guanghua Lu⁴, Saiyu Yuan⁵, Karina Yew-Hoong Gin³

Affiliations

¹ State Key Laboratory of Water Cycle and Water Security, Hohai University, Nanjing 210098, China; College of Environment, Hohai University, Nanjing 210098, China; Department of Civil and Environmental Engineering, National University of Singapore, 117576, Singapore.
² State Key Laboratory of Water Cycle and Water Security, Hohai University, Nanjing 210098, China; College of Environment, Hohai University, Nanjing 210098, China. Electronic address: hwahuer@126.com.
³ Department of Civil and Environmental Engineering, National University of Singapore, 117576, Singapore; NUS Environmental Research Institute, National University of Singapore, 117411, Singapore.
⁴ State Key Laboratory of Water Cycle and Water Security, Hohai University, Nanjing 210098, China; College of Environment, Hohai University, Nanjing 210098, China.
⁵ The National Key Laboratory of Water Disaster Prevention, Hohai University, Nanjing 210098, China.

PMID: 41795362
DOI: 10.1016/j.watres.2026.125659

Abstract

Antibiotic resistance genes (ARGs) prevalence has raised increasing concern due to their potential risks for ecological safety and human health. Although the plastisphere has been recognized as a hotspot for ARG spread, little is known about how the hydrological exchange reshapes ARG dissemination in plastisphere, which frequently occurs in the hyporheic zone (HZ) with its vertical upwelling and downwelling flows. To fill this knowledge gap, this study investigated ARG propagation in vertically distributed plastispheres within HZ under various hydrological exchange scenarios. Results showed that hydrological exchange lowered ARG abundance in the HZ plastisphere. Vertically, upwelling shifted the ARG enrichment pattern toward the surface plastisphere, whereas ARGs were bottom-enriched under no-water exchange. In addition, hydrological exchange reassembled microbial communities in plastisphere, with upwelling leading to higher microbial species richness and diversity. Notably, the upwelling plastisphere substantially enriched nitrifying bacteria and genes, exhibiting negative effects on ARG spread. Compared with surface plastisphere, the ARGs-host interactions were more complex in the bottom plastisphere, and upwelling weakened the complexity. Moreover, the ARG abundance in the plastisphere was significantly and positively correlated with mobile genetic element (MGE) abundance (Pearson's R = 0.687-0.997, P < 0.05), indicating a high potential of horizontal gene transfer (HGT) that is mainly regulated by transposase and integrase. Overall, N-cycling and HGT jointly regulated ARG dissemination in the HZ plastisphere under hydrological exchange, but exerted opposite effects with N-cycling acting as a suppressive factor whereas HGT promoted ARG propagation. These findings provide new insights into the ARGs propagation in the plastisphere in HZ, highlighting the significant roles of hydrological exchange on antimicrobial resistance under increasing global nitrate pollution in groundwater.

Keywords: Antibiotic resistance genes (ARGs); Hydrological exchange; Hyporheic zone (HZ); Nitrogen cycling; Plastisphere.

MeSH terms

Bacteria / genetics
Drug Resistance, Microbial* / genetics
Hydrology