摘要

       越来越多的证据表明，重金属污染可以通过共选择促进抗生素抗性基因 (ARG) 的增殖。然而，纳米金属材料对土壤和植物中 ARGs 的发生和水平的影响尚未得到充分探索。为了深入了解这种影响，我们通过添加纳米银粒子 (AgNPs) 作为刺激物和银离子 (AgNO3) 和四环素作为比较，进行了盆栽实验。通过使用高通量定量 PCR，我们的结果表明，以 100ppm 的浓度应用 AgNPs（~20nm 和~50nm）导致土壤或叶际中 ARGs 的丰度没有显着变化（P>0.05）。然而，在施用 AgNPs 后，抵抗组的整体模式，尤其是在土壤中，发生了变化，外排泵基因的相对丰度显着增加，这是重金属共同选择 ARGs 的重要机制。相比之下，与 AgNPs 相同质量的 Ag 离子显着增加了 ARGs 丰度并改变了土壤中的 ARGs 分布，表明游离 Ag 离子对 ARGs 的影响比 AgNPs 更强。这些发现为评估在环境中积累的人造纳米材料的风险提供了新的见解。

       Growing evidences have demonstrated that heavy metal contamination can promote the proliferation of antibiotic resistance genes (ARGs) via co-selection. However, effects of nano-metal-materials on the occurrence and level of ARGs in the soil and plant, have not been fully explored. To gain insights into this impact, we conducted a pot experiment by adding nano‑silver particles (AgNPs) as a stimuli and Ag ion (AgNO3) and tetracycline as a comparison. By using high throughput quantitative PCR, our results indicated that application of AgNPs (~20 nm and ~50 nm) at a concentration of 100 ppm resulted in no significant changes in the abundance of ARGs in either soil or phyllosphere (P > 0.05). Nevertheless, the overall pattern of resistome, especially in soil, was shifted following AgNPs application, with a significance increase in the relative abundance of efflux pumps genes, which is an important mechanism for co-selection of ARGs by heavy metals. By comparison, Ag ion at an equivalent Ag mass of AgNPs markedly increased ARGs abundance and shifted ARGs profile in soil, indicating that free Ag ion had a stronger impact on ARGs than AgNPs. These findings provide new insights in assessing the risks of manufactured nanomaterials accumulated in the environment.

https://www.sciencedirect.com/science/article/pii/S0160412019311419