Metagenomic investigations of microbial community response and antibiotic resistance genes in river sediments polluted by perfluoroalkyl acids.

Liquid-solid phase transfer promotes the interaction of perfluoroalkyl acids (PFAAs) with the microbial system of river sediments, which may affect the environmental behavior of antibiotic resistance genes (ARGs) contained in benthic environments. Sediments collected from the receiving water of the largest fluoropolymer production facility in China were analyzed to investigate the impact of PFAAs on microbial communities and ARG profiles. The main contributors to the PFAAs were perfluorooctanoic acid and perfluorobutanoic acid, whose proportions (86.9 %-93.4 %) in the downstream surface sediments affected by industrial effluents were significantly higher than in the corresponding upstream samples (53.3 %). A reduction in microbial diversity and richness was observed in the presence of high concentrations of PFAAs at the downstream sites. 144 ARG subtypes, including three high-risk subtypes (bacA, aac (6')-I and aadA), were identified in sediment samples. The discharge of fluorochemical effluents also results in a reduction of ARG diversity at subtype level. PFAAs exert a pronounced influence on the profile of ARGs in sediment. PFAAs and water quality parameters (e.g. pH and total phosphorus) were key drivers of the microbial community composition in the sediment. The regulation of microbial communities by PFAAs may represent an important pathway by which these compounds affect ARG profiles.