Environmental fate of Bacteroidetes, with particular emphasis on Bacteroides fragilis group bacteria and their specific antibiotic resistance genes, in activated sludge wastewater treatment plants

[Display omitted] •The impact of sewage treatment processes on BFG bacteria has been examined.•The prevalence of antibiotic resistance genes in wastewaters has been determined.•Wastewater treatment processes affect the number of copies of ARGs.•The presence of BFG genes was correlated to ARGs concentrations in wastewater. The aim of this study was to determine the effect of the activated sludge process on the abundance of anaerobic bacteria of the phylum Bacteroidetes, with special emphasis on Bacteroides fragilis group (BFG) bacteria, in twelve full-scale wastewater treatment plants. The composition of bacterial phyla and classes in wastewater samples were analyzed by next-generation sequencing. The presence of specific to BFG bacteria genes and the abundance of ARGs and genes encoding class 1 integrase in wastewater samples were determined by qPCR. Proteobacteria, Firmicutes, Actinobacteria and Bacteroidetes were dominant bacterial phyla in wastewater samples. Next-generation sequencing revealed similar proportions of Bacteroidia (