Herbicide promotes the conjugative transfer of multi-resistance genes by facilitating cellular contact and plasmid transfer

The global dissemination of antibiotic resistance genes (ARGs), especially via plasmidmediated horizontal transfer, is becoming a pervasive health threat. While our previous study found that herbicides can accelerate the horizontal gene transfer (HGT) of ARGs in soil bacteria, the underlying mechanisms by which herbicides promote the HGT of ARGs across and within bacterial genera are still unclear. Here, the underlying mechanism associated with herbicide-promoted HGT was analyzed by detecting intracellular reactive oxygen species (ROS) production, extracellular polymeric substance composition, cell membrane integrity and proton motive force combined with genome-wide RNA sequencing. Exposure to herbicides induced a series of the above bacterial responses to promote HGT except for the ROS response, including compact cell-to-cell contact by enhancing pilus-encoded gene expression and decreasing cell surface charge, increasing cell membrane permeability, and enhancing the proton motive force, providing additional power for DNA uptake. This study provides a mechanistic understanding of the risk of bacterial resistance spread promoted by herbicides, which elucidates a new perspective on nonantibiotic agrochemical acceleration of the HGT of ARGs. (c) 2021 The Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V.

Automated summary

This study analyzed the underlying mechanism associated with herbicide-promoted horizontal gene transfer (HGT) by detecting intracellular reactive oxygen species (ROS) production, extracellular polymeric substance composition, cell membrane integrity, and proton motive force combined with genome-wide RNA sequencing. The study found that exposure to herbicides induced bacterial responses that promote HGT, including enhancing pilus-encoded gene expression and decreasing cell surface charge, increasing cell membrane permeability, and enhancing the proton motive force. This study provides a mechanistic understanding of the risk of bacterial resistance spread promoted by herbicides, revealing a new perspective on non-antibiotic agrochemical acceleration of the HGT of antibiotic resistance genes.