Triclosan facilitates the dissemination of antibiotic resistance genes during anaerobic digestion: Focusing on horizontal transfer and microbial response

The present study aims to investigate the mechanism by which triclosan influences the dissemination of antibiotic resistance genes (ARGs) during the whole anaerobic digestion process. qPCR and metagenomic analyses revealed that triclosan facilitated ARGs dissemination in a dose- and time-dependent manner. Furthermore, integrons exhibited a significant correlation with the majority of quantified ARGs, and various ARGs were frequently linked on integron gene cassettes. Microbial community and redundancy analyses indicated that triclosan altered the components of dominant ARGs hosts Firmicutes, Synergistetes and Bacteroidetes. Path modeling analysis confirmed integrons were the main driving force for facilitating ARGs dissemination. The promoted ARGs dissemination may be associated with the increased reactive oxygen species generation, cell membrane permeability, close-connected the ARGs transfer related regulatory proteins induced by triclosan. This study broadens the understanding of triclosan facilitates ARGs dissemination through anaerobic treatment, the strategies for preventing potential risks should be proposed in practice.