Center of Excellence for Science and Technology-Integration of Mediterranean Region, University of Split, Ruđera Boškovića 31, 21000, Split, Croatia; Faculty of Science, University of Split, Ruđera Boškovića 33, Split, Croatia.
Department of Informatics, Faculty of Science, University of Split, Ruđera Boškovića 33, 21000, Split, Croatia.
Environ Pollut. 2022 Jan 1;292(Pt A):118282. doi: 10.1016/j.envpol.2021.118282. Epub 2021 Oct 4.
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.
污水处理厂（WWTP）的废水被认为是将共生菌和病原菌及其抗生素耐药基因（ARGs）引入受纳水体的热点。本研究首次探索了经部分处理的海底污水在水柱底部和表面的排放对微生物组结构及相关 AR 的影响，并评估了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污水排放口采集了 5 个月的海水样本。使用 16S rRNA 扩增子测序来建立细菌群落的分类和抗性组图谱。两个排放区之间观察到的群落差异，特别是在变形菌门和厚壁菌门的丰度上的差异，可能是由于 WWTP 处理的废水来源以及温度和营养等限制环境条件的不同造成的。PICRUSt2 分析推断了研究微生物组中 ARGs 的总含量，并显示出编码多药外排泵的耐药基因（如 MexAB-OprM、AcrEF-TolC 和 MdtEF-TolC）的最高丰度，其次是修饰的肽聚糖前体、编码四环素、大环内酯和青霉素耐药的转运基因，以及赋予β-内酰胺耐药性的 bla 操纵子。由废水引入的许多病原菌属，包括不动杆菌属、弯曲杆菌属、拟杆菌属、大肠埃希氏菌-志贺氏菌属、克雷伯菌属、假单胞菌属和沙门氏菌属，被预测为大多数外排泵驱动的多药耐药的主要贡献者，而不动杆菌属、沙门氏菌属、拟杆菌属和假单胞菌属也被证明是携带非外排 ARGs 的主要载体，这些 ARGs 赋予了对 9 类抗生素的耐药性。综上所述，我们通过改变水柱的理化特性和非本地分类群的富集，证明了海底污水排放对受纳水体的负面影响，这些非本地分类群携带了大量的 ARGs，这可能导致 AR 在自然环境中的进一步传播。
