Bacteria in water
The global spread of plasmid-borne antibiotic resistance is an ongoing global health challenge. Conjugation is one of the major horizontal gene transfer pathways between bacterial species. Bioelectrochemical system (BES) is considered as an effective approach in reducing the concentration of antibiotics and the abundance of ARGs in wastewater. However, little is known about whether and how electrolysis stimulation can influence conjugation. In this study, we report that electrolysis stimulation can significantly promote the conjugative transfer mediated by ARGs-carrying plasmid. Noteworthy, we verified this phenomenon at the microbial community level via fluorescence-activated cell sorting and 16S rRNA gene amplicon sequencing. Special attention should be paid to the fact that some opportunistic pathogens to animal and human beings become susceptive to obtain the antibiotic resistance under electrolysis stimulation. We also reveal the underlying mechanisms of enhanced conjugative transfer, including that electrolysis increases the number of mating cells, induces the production of reactive oxygen species, increases cell membrane permeability, damages cell membrane integrity, and upregulates the expression of conjugation relevant genes. Given the promotion of electrolysis stimulation in disseminating ARGs, our findings challenge the one-sided knowledge that BES reduces the public risk of ARGs in wastewater.