摘要
      作为抗生素抗性基因（ARGs）传播的热点，废水处理厂（WWTP）引起了全球的关注。然而，对青藏高原污水处理厂的抗生素耐药性缺乏足够的宏基因组监测。本文采用宏基因组方法全面研究了青藏高原18个污水处理厂进水和出水中ARGs的发生、迁移潜力和细菌宿主。整个污水处理厂从进水到出水的总ARG相对丰度和多样性显著降低。多药、杆菌肽、磺酰胺、氨基糖苷和β-内酰胺类ARG通常是出水样品中的主要ARG类型，与进水样品不同。所有样本共有72个核心ARG，占总ARG丰度的61.8–95.8%。在进水（277个ARGs）和出水（178个ARG）中检测到主要赋予β-内酰胺类耐药性的临床相关ARGs。宏基因组组装显示，ARG在质粒或染色体上的遗传位置与其相应的ARG类型有关，这表明不同ARG类型的迁移潜力存在差异。在进水和出水中，质粒介导的ARGs的丰度比染色体介导的ARGs的丰度高得多。此外，在出水中与不同的可移动遗传元素共存的ARGs表现出与进水相当的流动潜力。此外，分配给13个细菌门的137个宏基因组组装基因组（MAG）被鉴定为ARG宿主，其可以在大多数WWTP中得到有效处理。值得注意的是，46个MAG被发现携带多种ARG类型，并且潜在的病原体经常表现出多种抗生素耐药性。某些ARG类型往往由某些细菌携带，表现出特定的宿主抗性关联模式。这项研究强调了宏基因组监测的必要性，并将有助于脆弱地区污水处理厂抗生素耐药性的风险评估和控制。
Abstract
As hotspots for the dissemination of antibiotic resistance genes (ARGs), wastewater treatment plants (WWTPs) have attracted global attention. However, there lacks a sufficient metagenomic surveillance of antibiotic resistome in the WWTPs located on the Qinghai-Tibet Plateau. Here, metagenomic approaches were used to comprehensively investigate the occurrence, mobility potential, and bacterial hosts of ARGs in influent and effluent of 18 WWTPs located on the Qinghai-Tibet Plateau. The total ARG relative abundances and diversity were significantly decreased from influent to effluent across the WWTPs. Multidrug, bacitracin, sulfonamide, aminoglycoside, and beta-lactam ARGs generally consisted of the main ARG types in effluent samples, which were distinct from influent samples. A group of 72 core ARGs accounting for 61.8–95.8 % of the total ARG abundances were shared by all samples. Clinically relevant ARGs mainly conferring resistance to beta-lactams were detected in influent (277 ARGs) and effluent (178 ARGs). Metagenomic assembly revealed that the genetic location of an ARG on a plasmid or a chromosome was related to its corresponding ARG type, demonstrating the distinction in the mobility potential of different ARG types. The abundance of plasmid-mediated ARGs accounted for a much higher proportion than that of chromosome-mediated ARGs in both influent and effluent. Moreover, the ARGs co-occurring with diverse mobile genetic elements in the effluent exhibited a comparable mobility potential with the influent. Furthermore, 137 metagenome-assembled genomes (MAGs) assigned to 13 bacterial phyla were identified as the ARG hosts, which could be effectively treated in most WWTPs. Notably, 46 MAGs were found to carry multiple ARG types and the potential pathogens frequently exhibited multi-antibiotic resistance. Some ARG types tended to be carried by certain bacteria, showing a specific host-resistance association pattern. This study highlights the necessity for metagenomic surveillance and will facilitate risk assessment and control of antibiotic resistome in WWTPs located on the vulnerable area.

https://www.sciencedirect.com/science/article/abs/pii/S0048969723006460