Environmental concentrations of surfactants as a trigger for climax of horizonal gene transfer of antibiotic resistance.

Ubiquitous antibiotic resistance genes (ARGs) is a significant global human health concern. Surfactants have been extensively used worldwide, and the consumption of surfactants containing hygiene, cleaning agents and disinfectants was multiplied during COVID-19 pandemic, which have caused significantly increased pollution of surfactants in aquatic environment. Whether such ever-increasing surfactant concentration boost dissemination risk of ARGs still remains unknown. Here the effects of three typical surfactants such as sodium dodecyl sulfate, cetyltrimethylammonium bromide and benzalkonium chloride on the transformation of pUC19 plasmid (2686 bp)-borne ARGs to recipient bacteria DH5ɑ were investigated. It was found that these surfactants at environmental concentrations facilitated horizonal gene transfer (HGT) via transformation. The transformation triggering concentrations for the three surfactants were 0.25-0.34 mg/L with a maximum increased transformation frequency of 13.51-22.93-fold. The mechanisms involved in activated HGT of ARGs via transformation triggered by surfactants could be mainly attributed to the increased production of reactive oxygen species, which further enhanced cell membrane permeability. These findings provide new sights for understanding of ARG propagation and also imply that the drastic rise of surfactant concentration in aquatic environment may significantly increase the dissemination risk of antibiotic resistance.