摘要

       在本研究中，我们调查了处理过的废水 (TWW) 灌溉对底土孔隙水中抗生素抗性基因 (ARG) 流行的影响，这是迄今为止未被充分认识的基质。我们假设 TWW 灌溉增加了底土孔隙水中的 ARG 流行率。使用多阶段方法对这一假设进行了测试，该方法包括从实际规模的 TWW 灌溉田的渗滤器井中采样渗透的底土孔隙水，用于商业农业实践，以及用淡水或 TWW 灌溉的受控实验室微观世界。我们监测了六个选定的 ARG（sul1、blaOXA-58、tetM、qnrS、blaCTX-M-32 和 blaTEM）的丰度、与移动遗传元件相关的 intI1 基因以及人为污染和细菌丰度的指标（16S rRNA 基因）通过 qPCR。底土孔隙水的细菌负荷与田间研究中的灌溉强度和微观世界中的灌溉水类型无关。在实地研究中测试的基因中，sul1 和 intI1 表现出不断更高的相对丰度。它们的丰度进一步与灌溉强度的增加呈正相关。受控微观实验验证了观察到的田间研究结果：与淡水灌溉相比，使用 TWW 灌溉时，包括 sul1 和 intI1 在内的几个基因的相对丰度显着增加。总体而言，TWW 灌溉促进了 ARGs 和 intI1 在底土孔隙水中的扩散，同时保持了细菌负荷。来自真实规模农田和受控实验室微观世界的综合结果表明，在 TWW 灌溉场景中，需要考虑 ARGs 在各种地下环境中的传播。

       In the present study, we investigated the impact of treated wastewater (TWW) irrigation on the prevalence of antibiotic resistance genes (ARGs) in subsoil pore-water, a so-far under-appreciated matrix. We hypothesized that TWW irrigation increases ARG prevalence in subsoil pore-water. This hypothesis was tested using a multiphase approach, which consisted of sampling percolated subsoil pore-water from lysimeter-wells of a real-scale TWW-irrigated field, operated for commercial farming practices, and controlled, laboratory microcosms irrigated with freshwater or TWW. We monitored the abundance of six selected ARGs (sul1, blaOXA-58, tetM, qnrS, blaCTX-M-32 and blaTEM), the intI1 gene associated with mobile genetic elements and an indicator for anthropogenic pollution and bacterial abundance (16S rRNA gene) by qPCR. The bacterial load of subsoil pore water was independent of both, irrigation intensity in the field study and irrigation water type in the microcosms. Among the tested genes in the field study, sul1 and intI1 exhibited constantly higher relative abundances. Their abundance was further positively correlated with increasing irrigation intensity. Controlled microcosm experiments verified the observed field study results: the relative abundance of several genes, including sul1 and intI1, increased significantly when irrigating with TWW compared to freshwater irrigation. Overall, TWW irrigation promoted the spread of ARGs and intI1 in the subsoil pore-water, while the bacterial load was maintained. The combined results from the real-scale agricultural field and the controlled lab microcosms indicate that the dissemination of ARGs in various subsurface environments needs to be taken into account during TWW irrigation scenarios.

https://www.sciencedirect.com/science/article/pii/S0160412020321450