摘要

  大型污水处理厂 (WWTP) 每年向地表水中排放数百吨总悬浮固体 (TSS)。此外，在联合下水道系统的情况下，在大雨事件期间下水道溢流会释放出相当的数量。随着沉淀，附着颗粒的微生物及其抗生素抗性基因 (ARG) 被输送到接收水的河床。为了更好地了解该过程的动力学，将颗粒废水部分添加到以前充满天然河流沉积物和自来水的间歇反应器中。同时，添加抗生素 (AB)（红霉素、四环素、环丙沙星、罗红霉素、青霉素 V 和磺胺甲恶唑）以研究它们选择耐药性的能力。使用定量 PCR 对水域和沉积物中的 6 个 ARG（ermB、tetM、blaTEM、sul1、CTX-M-32 和 qnrS）以及总细菌（16S rDNA）的丰度进行了为期两个月的监测。尽管持续暴露于 AB（每个 5 μg/L），ARG 的丰度仍然不受影响。废水颗粒的添加导致水（3-5 log 单位）和沉积物（1-4 log 单位）中 ARG 的突然和强烈增加，但是，升高的 ARG 经历了特定且完全的衰减。我们的结果表明，接收河流中 ARG 丰度的增加是由于污水处理厂排放或下水道溢流事件中 ARG 持续输入的结果。它们进一步暗示，如果去除这种持续的输入，升高的 ARG 不会在接收河流中持续存在。考虑到在本地人口中观察到稳定的 ARG 背景浓度，这似乎仅适用于废水引入的 ARG。

  Large-scale wastewater treatment plants (WWTPs) discharge hundreds of tons of total suspended solids (TSS) into surface waters every year. Additionally, a comparable amount is released by sewer overflows during heavy rain events in case of combined sewer systems. Along with sedimentation, particle-attached microorganisms and their antibiotic resistance genes (ARGs) are herewith transported to the riverbed of the receiving water. To better understand the dynamics of this process, a particulate wastewater fraction was added into batch reactors, which were previously filled with natural river sediments and tap water. In parallel, antibiotics (ABs) (erythromycin, tetracycline, ciprofloxacin, roxithromycin, penicillin V, and sulfamethoxazole) were spiked to investigate their capability to select for resistance. The abundance of six ARGs (ermB, tetM, blaTEM, sul1, CTX-M-32, and qnrS) as well as total bacteria (16S rDNA) was monitored in waters and in sediments for a duration of two months using quantitative PCR. Despite a continuous exposure to ABs (5 μg/L each), the abundance of ARGs remained unaffected. Addition of wastewater particles resulted in a sudden and strong increase of ARGs in waters (3–5 log units) and sediments (1–4 log units), however, elevated ARGs underwent a particular and complete decay. Our results indicate that the increased ARG abundances in receiving rivers are the result of a continuous import of ARGs from WWTP discharges or sewer overflow events. They further imply that elevated ARGs do not persist in receiving rivers, if this continuous import is removed. This seems to be the case merely for ARGs introduced by wastewater, given that a stable background concentration of ARGs was observed for the native population.

  https://www.sciencedirect.com/science/article/abs/pii/S0048969719358565