Institute of Organic Contaminant Control and Soil Remediation, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, 210095, PR China.
Institute of Organic Contaminant Control and Soil Remediation, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, 210095, PR China.
Chemosphere. 2023 Mar;318:137997. doi: 10.1016/j.chemosphere.2023.137997. Epub 2023 Jan 28.
A vast number of bacteria occur in both soil and plants, with some of them harboring antibiotic resistance genes (ARGs). When bacteria congregate on the interface of soil particles or on plant root surfaces, these ARGs can be transferred between bacteria via conjugation, leading to the formation of antibiotic-resistant pathogens that threaten human health. Plant growth regulators (PGRs) are widely used in agricultural production, promoting plant growth and increasing crop yields. However, until now, little information has been known about the effects of PGRs on the horizontal gene transfer (HGT) of ARGs. In this study, with Escherichia coli DH5α (carrying RP4 plasmid with Tet, Amp, Kan) as the donor and E. coli HB101 as the recipient, a series of diparental conjugation experiments were conducted to investigate the effects of indoleacetic acid (IAA), ethel (ETH) and gibberellin (GA) on HGT of ARGs via plasmid-mediated conjugation. Furthermore, the mechanisms involved were also clarified. The results showed that all three PGRs affected the ARG transfer frequency by inducing the intracellular reactive oxygen species (ROS) formation, changing the cell membrane permeability, and regulating the gene transcription of traA, traL, trfAp, trbBp, kilA, and korA in plasmid RP4. In detail, 50-100 mg⋅L IAA, 20-50 mg⋅L ETH and 1500-2500 mg⋅L GA all significantly promoted the ARG conjugation. This study indicated that widespread use of PGRs in agricultural production could affect the HGT of ARGs via plasmid-mediated conjugation, and the application of reasonable concentrations of PGRs could reduce the ARG transmission in both soil environments and plants.
大量细菌存在于土壤和植物中，其中一些携带有抗生素抗性基因（ARGs）。当细菌聚集在土壤颗粒的界面或植物根部表面时，这些 ARGs 可以通过接合在细菌之间转移，导致形成对抗生素具有抗性的病原体，从而威胁到人类健康。植物生长调节剂（PGRs）广泛应用于农业生产中，促进植物生长，提高作物产量。然而，到目前为止，人们对 PGRs 对 ARGs 水平基因转移（HGT）的影响知之甚少。在这项研究中，以携带 Tet、Amp、Kan 的 RP4 质粒的大肠杆菌 DH5α（Escherichia coli DH5α）为供体，以大肠杆菌 HB101 为受体，进行了一系列的双亲接合实验，以研究吲哚乙酸（IAA）、乙稀（ETH）和赤霉素（GA）对通过质粒介导的接合转移 ARGs 的影响，并阐明了相关机制。结果表明，这三种 PGRs 都通过诱导细胞内活性氧（ROS）的形成、改变细胞膜通透性以及调节质粒 RP4 中 traA、traL、trfAp、trbBp、kilA 和 korA 的基因转录来影响 ARG 转移频率。具体而言，50-100mg⋅L 的 IAA、20-50mg⋅L 的 ETH 和 1500-2500mg⋅L 的 GA 均显著促进了 ARG 的接合。本研究表明，农业生产中广泛使用 PGRs 可能会通过质粒介导的接合影响 ARGs 的 HGT，合理浓度的 PGRs 的应用可以减少土壤环境和植物中 ARG 的传播。
