摘要
      污水处理厂（WWTP）的废水被认为是共生菌和致病菌及其抗生素抗性基因（ARGs）在接收水体中引入的热点。首次在水柱底部和表面探索了部分处理的海底污水的影响，以全面概述微生物组和相关AR的结构，并评估导致其变化的环境因素。在克罗地亚亚得里亚海中部的海底排水口采集了5个月的海水样本。16S rRNA扩增子测序用于建立细菌群落的分类和抗性谱。在两个排放区之间观察到的群落差异，特别是变形杆菌和厚壁菌门的丰度，可能是由于污水处理厂处理的废水的来源以及温度和营养物质等有限的环境条件造成的。PICRUSt2分析推断了所研究的微生物群中ARGs的总含量，并显示编码多药外排泵的抗性基因丰度最高，如MexAB OprM、AcrEF TolC和MdtEF TolC，其次是修饰的肽聚糖前体、编码四环素、大环内酯和氯霉素抗性的转运蛋白基因，以及赋予β-内酰胺抗性的bla操纵子。流出物引入的许多致病属，包括不动杆菌、Arcobacter、拟杆菌、埃希氏志贺菌、克雷伯菌、假单胞菌和沙门氏菌，被预测为外排泵驱动的多药耐药性的主要原因，拟杆菌和假单胞菌也被证明是非外排ARGs的主要携带者，对九类抗生素中的大多数产生耐药性。总之，我们通过改变水柱的物理化学特征和富集携带ARGs库的非原生类群，证明了海底排放处理过的污水的负面影响，这可能有助于AR在自然环境中的进一步传播。
Abstract
Wastewater treatment plant (WWTP) effluents are pointed as hotspots for the introduction of both commensal and pathogenic bacteria as well as their antibiotic resistance genes (ARGs) in receiving water bodies. For the first time, the effect of partially treated submarine effluents was explored at the bottom and surface of the water column to provide a comprehensive overview of the structure of the microbiome and associated AR, and to assess environmental factors leading to their alteration. Seawater samples were collected over a 5-month period from submarine outfalls in central Adriatic Sea, Croatia. 16S rRNA amplicon sequencing was used to establish taxonomic and resistome profiles of the bacterial communities. The community differences observed between the two discharge areas, especially in the abundance of Proteobacteria and Firmicutes, could be due to the origin of wastewaters treated in WWTPs and the limiting environmental conditions such as temperature and nutrients. PICRUSt2 analysis inferred the total content of ARGs in the studied microbiomes and showed the highest abundance of resistance genes encoding multidrug efflux pumps, such as MexAB-OprM, AcrEF-TolC and MdtEF-TolC, followed by the modified peptidoglycan precursors, transporter genes encoding tetracycline, macrolide and phenicol resistance, and the bla operon conferring β-lactam resistance. A number of pathogenic genera introduced by effluents, including Acinetobacter, Arcobacter, Bacteroides, Escherichia-Shigella, Klebsiella, Pseudomonas, and Salmonella, were predicted to account for the majority of efflux pump-driven multidrug resistance, while Acinetobacter, Salmonella, Bacteroides and Pseudomonas were also shown to be the predominant carriers of non-efflux ARGs conferring resistance to most of nine antibiotic classes. Taken together, we evidenced the negative impact of submarine discharges of treated effluents via alteration of physico-chemical characteristics of the water column and enrichment of bacterial community with nonindigenous taxa carrying an arsenal of ARGs, which could contribute to the further propagation of the AR in the natural environment.

https://www.sciencedirect.com/science/article/abs/pii/S0269749121018649