摘要
      抗生素耐药性基因在病原体中的传播正在成为一种普遍的全球健康威胁，环境的重要性越来越受到关注。然而，天然矿物如何影响病原体中ARGs的转移仍不清楚。在本研究中，探讨了赤铁矿的浓度和大小对ARGs偶联转移到常见人畜共患病原体大肠杆菌O157:H7的影响及其潜在机制。结果表明，与纳米赤铁矿不同，块状赤铁矿在任何浓度（1-100 mg/L）下都能抑制细胞生长，从而减少抗性质粒的结合。与对照组相比，低浓度的纳米赤铁矿（≤25 mg/L）导致偶联转移频率显著增加1.83–4.49倍，而其高浓度（50和100 mg/L）没有显示出影响。这种低浓度效应可能归因于细胞内ROS水平的增加、通过增加细胞外聚合物物质的产生和细胞表面疏水性而减少的细胞间排斥、转移通道的形成以及通过基因表达水平的显著变化证明的膜通透性的增加，以及通过增加受体的跨膜电位而增加的质子原动力。这些发现揭示了纳米矿物介导的ARGs在环境中病原体中传播所引起的潜在健康风险。
Abstract
The dissemination of antibiotic resistance genes (ARGs) in pathogens is becoming a pervasive global health threat, to which the importance of the environment attracts more and more attention. However, how natural minerals affect ARGs transfer in pathogens is still unclear. In this study, the concentration and size effects of hematite on the ARGs conjugative transfer to a common zoonotic pathogen Escherichia coli O157:H7 and underlying mechanisms were explored. Results revealed that bulk hematite reduced the conjugation of resistant plasmids by inhibiting cell growth at any concentration (1–100 mg/L), different from nano-hematite. Low concentrations of nano-hematite (≤ 25 mg/L) induced significant increases in conjugative transfer frequency of 1.83–4.49 folds, while its high concentrations (50 and 100 mg/L) showed no impact, compared with the control group. This low-concentration effect was likely attributed to the increased intracellular ROS level, the reduced intercellular repulsion by increasing the extracellular polymeric substances production and cell surface hydrophobicity, the formation of transfer channels and the increased membrane permeability evidenced by significant changes in gene expression level, and the increased proton motive force by increasing the transmembrane potential of recipients. These findings shed light on potential health risks caused by nano minerals-mediated ARGs dissemination in pathogens in the environment.

https://www.sciencedirect.com/science/article/abs/pii/S0304389422003259