PFAS Stress on Functional Expression of Periphyton Communities and Trade-off Strategies for Horizontal/Vertical Transfer of Resistance Genes

The dissemination of antibiotic resistance genes (ARGs) induced by perfluoroalkyl and polyfluoroalkyl substances (PFAS) and their ecological impacts have gained significant attention. Periphyton communities on sediments play crucial hydroecological roles and serve as bioindicators of PFAS contamination. However, research on their microbial structure and ARG dissemination in response to PFAS remains limited. This study explored how PFAS stress influences periphyton communities' ecological functions and ARGs dynamics. PFAS varying exposure inhibited communities' formation by decreasing biomass (3.0-26.2%) and significantly reducing protein and polysaccharides (<i>p</i> < 0.05) of periphyton communities. Methanogenic archaea abundance increased by 4.79-159290 times, while <i>Variovorax</i> and <i>Nitrospira</i> decreased by 1266.1-2303.5 and 36.1-140.4 times, respectively. Notably, PFAS enhanced ARGs families (multidrug, aminoglycoside, and glycopeptide) and subtypes (<i>macB</i>, <i>evgS</i>, <i>tetA58</i>, and <i>bcrA</i>), strengthening correlations between the mobile genetic elements (MGEs) and antibiotic efflux (<i>R</i>² = 0.941) or target alteration (<i>R</i>² = 0.961). Horizontal gene transfer (HGT) mediated by MGEs played a dominant role in ARGs dissemination compared to vertical gene transfer in periphyton communities. Mechanistic insights revealed that PFAS-induced reactive oxygen species elevation, increased membrane permeability, enhanced energy provision, and overexpression of adherent molecular genes collectively facilitated HGT-driven ARGs spread. This study provides new insights into the complex interactions between PFAS and ARGs and its potential risks in microbial habitats.