Ionic Liquid Facilitates the Conjugative Transfer of Antibiotic Resistance Genes Mediated by Plasmid RP4

Abstract

The dissemination and propagation of antibiotic resistance genes (ARGs) is an emerging global health concern. In our previous study, the ionic liquid (IL) 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIm][PF6]) had been proven to facilitate the dissemination of ARGs via horizontal gene transfer. In this study, we further confirm that this compound facilitates the horizontal transfer of plasmid RP4 through a conjugation mechanism and not by natural transformation. The mechanisms for [BMIm][PF6] promoting conjugative transfer are attributable to enhancing the mRNA expression levels of conjugative and global regulatory genes, as well as by inhibiting the genes that are responsible for the vertical transfer of cell growth. [BMIm][PF6] significantly enhanced the expression of the outer membrane porin proteins (OMPs) OmpC and OmpA and the corresponding mRNA expression levels of ompC and ompA genes in recipient bacteria, which contributed to pore formation and increased cell membrane permeability. The increased expression of pilin and pili allowed the donor pilus to attach to and access the recipient cells, thereby assisting cell-to-cell contact to facilitate the conjugative transfer of plasmid RP4. To the best of our knowledge, this is the first insightful exploration of [BMIm][PF6] facilitating the conjugative transfer of ARGs mediated by plasmid RP4 and of several other ILs with different cations or anions that are capable of promoting plasmid transfer. It is therefore suggested that the application of some ILs in industrial processes should be carefully evaluated before their bulk emission into the environment.

Polycyclic aromatic hydrocarbons (PAHs) enriching antibiotic resistance genes (ARGs) in the soils

“…ARGs are able to horizontally spread between bacteria via transformation or conjugation under antibiotic stresses, thereby ARGs being enriched in the human-impacted environment (Cottell et al, 2014;Turner et al, 2014). Such gene transfers require plasmids as the shuttling carriers between bacteria (Wang et al, 2015). For instance, the concurrence of metal and antibiotic resistance genes in the plasmids facilitates the dissemination of these genes under elevated stresses caused by either heavy metals or antibiotics (Li et al, 2015a;Zhai et al, 2016).…”

“…Moreover, ARGs could be amplified in the environment under elevated selective stress via two distinct pathways, viz. the overgrowth of ARGs-carrying indigenous bacteria, or horizontal gene transfer of ARGs between bacteria using mobile gene elements (MGEs) as the carriers (e.g., plasmids, transposons and integrons) (Engelstadter et al, 2016;Knapp et al, 2008;Wang et al, 2015). Therefore, analysis of bacterial community and identification of genetic location of ARGs could be beneficial to gain more insights about how ARGs are accumulated in the PAHs-contaminated soils.…”

Chlorine disinfection increases both intracellular and extracellular antibiotic resistance genes in a full-scale wastewater treatment plant

“…Urban wastewater treatment plants (UWWTPs) are at the interface between human population and the aquatic/soil environments, may provide an ideal setting for the acquisition and dissemination of antibiotic resistance, because a diverse mixture of antibiotics and other pollutants, their metabolites and resistant bacteria, reaches UWWTPs through wastewater discharges from hospitals, households, industries and animal farms (Guo et al, 2017). The prevalence of ARB and ARGs in UWWTPs has attracted more and more attention recently (Chen and Zhang 2013, Naquin et al, 2015, Wang et al, 2015, Wen et al, 2016. In particular, biological reactors in activated sludge systems are thought as one of critical compartments in harboring both ARB and ARGs (Rizzo et al, 2013, Yang et al, 2012, through selection under exposure of antibiotic or resistance transfer among bacteria via horizontal gene transfer (HGT) (Jutkina et al, 2016, Kim et al, 2014.…”

“…In particular, biological reactors in activated sludge systems are thought as one of critical compartments in harboring both ARB and ARGs (Rizzo et al, 2013, Yang et al, 2012, through selection under exposure of antibiotic or resistance transfer among bacteria via horizontal gene transfer (HGT) (Jutkina et al, 2016, Kim et al, 2014. More importantly, it has been reported that UWWTPs exhibit limited capacity to remove or control ARGs and ARB (Munir et al, 2011, Pruden et al, 2006, Wang et al, 2015. Worryingly, not only does the effluent M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT 4 represent an important reservoir containing various ARGs, but also the abundances of some typical ARGs are even higher in effluent than that in influent via the treatment processes, e.g.…”

Modified U-Tube for Ruling out Naked DNA Transfer during Conjugation and Application in Antibiotic Resistance Genes Transfer Research

“…Therefore, investigation of the transfer of eARGs can aid in better understanding and clarification of their contribution to the dissemination of ARGs. In previous studies, naked DNA (extracted from donor bacteria) was directly added to the recipient system and used as control for ruling out the natural transformation in the conjugative transfer process [28]. However, this method does not accurately estimate the interference of transformation.…”