摘要

       抗生素抗性基因 (ARGs) 的传播是世界范围内一个新兴的健康问题。因此，了解并减少它们在不同系统中的发生非常重要。在这项研究中，在中国北方的两个活性污泥废水处理厂 (WWTP) 中检测到 30 种对四环素、磺胺、喹诺酮或大环内酯具有抗性的 ARG。携带 ARG 的细菌在所有处理单元中持续存在，并且在通过氯化消毒后存活的百分比高于总细菌（通过 16S rRNA 基因评估）。尽管从原始进水到出水的 ARG 的绝对丰度降低了 89.0%–99.8%，但在污水处理厂中发现了相当大的 ARG 水平 [(1.0 ± 0.2) × 103 至 (9.5 ± 1.8) × 105 拷贝/mL)]流出物样品。 ARGs 以 (1.5 ± 2.3) × 109 至 (2.2 ± 2.8) × 1011 份/克干重浓缩在废污泥中（通过细菌沉降和污泥脱水）。十二个 ARG（tetA、tetB、tetE、tetG、tetH、tetS、tetT、tetX、sul1、sul2、qnrB、ermC）以高于流入值的速率通过脱水污泥和工厂流出物排放，表明抗性细菌的总体增殖。在所有处理单元中仍保持显着的抗生素浓度（原始进水浓度的 2%–50%）。这显然为 ARG 复制提供了选择压力，因为抗性细菌的相对丰度（通过 ARG/16S rRNA 基因比率评估）与相应的流出物抗生素浓度显着相关。同样，各种重金属的浓度（诱导与抗生素类似的细菌耐药机制——外排泵）也与一些 ARG 的富集有关。因此，减少抗生素和重金属向污水系统的释放（或在预处理单元中加强它们的去除）可以减轻它们的选择压力并减轻污水处理厂中 ARG 的扩散。

       The propagation of antibiotic resistance genes (ARGs) is an emerging health concern worldwide. Thus, it is important to understand and mitigate their occurrence in different systems. In this study, 30 ARGs that confer resistance to tetracyclines, sulfonamides, quinolones or macrolides were detected in two activated sludge wastewater treatment plants (WWTPs) in northern China. Bacteria harboring ARGs persisted through all treatment units, and survived disinfection by chlorination in greater percentages than total Bacteria (assessed by 16S rRNA genes). Although the absolute abundances of ARGs were reduced from the raw influent to the effluent by 89.0%–99.8%, considerable ARG levels [(1.0 ± 0.2) × 103 to (9.5 ± 1.8) × 105 copies/mL)] were found in WWTP effluent samples. ARGs were concentrated in the waste sludge (through settling of bacteria and sludge dewatering) at (1.5 ± 2.3) × 109 to (2.2 ± 2.8) × 1011 copies/g dry weight. Twelve ARGs (tetA, tetB, tetE, tetG, tetH, tetS, tetT, tetX, sul1, sul2, qnrB, ermC) were discharged through the dewatered sludge and plant effluent at higher rates than influent values, indicating overall proliferation of resistant bacteria. Significant antibiotic concentrations (2%–50% of raw influent concentrations) remained throughout all treatment units. This apparently contributed selective pressure for ARG replication since the relative abundance of resistant bacteria (assessed by ARG/16S rRNA gene ratios) was significantly correlated to the corresponding effluent antibiotic concentrations. Similarly, the concentrations of various heavy metals (which induce a similar bacterial resistance mechanism as antibiotics – efflux pumps) were also correlated to the enrichment of some ARGs. Thus, curtailing the release of antibiotics and heavy metals to sewage systems (or enhancing their removal in pre-treatment units) may alleviate their selective pressure and mitigate ARG proliferation in WWTPs.

https://www.sciencedirect.com/science/article/abs/pii/S0043135415302220