摘要

       广泛的抗生素抗性基因 (ARG) 在全球范围内对公共健康造成了严重威胁。土壤主要由矿物质组成，是抗性决定因素的来源，在 ARG 的发展和传播中发挥着重要作用。土壤环境中大量的 ARGs 引起了人们对矿物质对 ARGs 传播的影响的担忧。在此，在暴露于四种常见土壤矿物质（高岭石、蒙脱石、针铁矿和水钠锰矿）后，监测了含有来自大肠杆菌S17-1 的 ARG 的模型质粒 pMP2463 向恶臭假单胞菌 KT2440 的水平转移。与对照组相比，Birnessite 导致质粒 pMP2463 结合转移的浓度依赖性增加 1.3-4.3 倍。然而，在不同浓度的高岭石和蒙脱石中，共轭转移率的变化没有发现明显的规律。对于针铁矿，随着浓度的增加，共轭转移率先增加后降低。探讨了水钠锰矿诱导质粒结合转移的可能机制；水钠锰矿能够启动细胞内活性氧 (ROS) 的形成，诱导氧化应激反应。此外，水钠石显着促进了外膜蛋白基因的 mRNA 表达，这有助于细胞膜孔的形成和水平基因转移，并改变了负责细菌间移动遗传元件接合转移的接合相关基因的 mRNA 表达。这项研究引发了有关土壤矿物质在全球抗菌素耐药性传播中的潜在作用的问题，并提供了对天然土壤环境中细菌和矿物质之间相互作用的见解。

       Widespread antibiotic resistance genes (ARGs) have caused critical threats to public health on a global scale. Soil, composed mainly of minerals, acts as a source of resistance determinants, playing a considerable role in the development and dissemination of ARGs. The great abundance of ARGs in the soil environment raises concern about the effect of minerals on the spread of ARGs. Herein, the horizontal transfer of a model plasmid pMP2463 containing ARGs from Escherichia coli S17-1 to Pseudomonas putida KT2440 was monitored following exposure to four common soil minerals, namely, kaolinite, montmorillonite, goethite and birnessite. Birnessite resulted in concentration-dependent increases in conjugative transfer of plasmid pMP2463 by 1.3–4.3 fold, compared with that in the control group. However, no obvious laws were found in the change of conjugative transfer rate at different concentrations of kaolinite and montmorillonite. As for goethite, the conjugative transfer rate increased firstly and then decreased as the concentration increased. The possible mechanisms underlying birnessite-induced conjugative transfer of plasmid were explored; birnessite is capable of initiating intracellular reactive oxygen species (ROS) formation, inducing the oxidative stress response. Additionally, birnessite notably facilitated the mRNA expression of the outer membrane protein genes, which contributed to cellular membrane pore formation and horizontal gene transfer, and altered the mRNA expression of conjugative-related genes that are responsible for conjugative transfer of mobile genetic elements between bacteria. This study triggers questions regarding the potential role of soil minerals in the global dissemination of antimicrobial resistance and provides insights into the interactions between bacteria and minerals in the natural soil environment.

https://onlinelibrary.wiley.com/doi/abs/10.1111/ejss.13004