Triadimefon Promoted Plasmid-mediated Conjugative Transfer of Multiple Antibiotic Resistance Genes within Bacterial Genus

Institute of Coastal Environmental Pollution Control, Key Laboratory of Marine Environment and Ecology, Ministry of Education, Ocean University of China, Qingdao, China

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Abstract

The rapid spread of antibiotic resistance genes (ARGs) has been a worldwide threat to the public health, especially via horizontal gene transfer (HGT). Conjugation is one of the major pathways of HGT. Triadimefon (TF) is a broad-spectrum antifungal compound used to control rust and powdery mildew on crops. Nevertheless, it is not known whether TF could affect the conjugation of ARGs and potential molecular mechanisms. Here, the effects of TF on conjugative transfer of RP4 plasmid within Escherichia coli were systematically investigated. The results demonstrated that TF increased the transconjugant number by 1.41–2.21 folds and the frequency of conjugative transfer by 1.49–2.22 folds at concentrations of 0.1–10 mg/L. There was no obvious change in the number of donor and recipient strains in the mating system of intra-genus with TF. The main mechanisms include increasing intracellular reactive oxygen species and membrane permeability. Our findings highlight the promotion effect of TF on ARG conjugation, providing evidence of the risk of non-antibiotic agrochemical use in ARG dissemination.