School of Environmental Science & Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China.
School of Environmental Science & Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China.; Shanghai Institute of Pollution Control and Ecological Security, 800 Dongchuan Road, Shanghai 200240, China.
Water Res. 2020 Dec 15;187:116450. doi: 10.1016/j.watres.2020.116450. Epub 2020 Sep 23.
Serious concerns have been raised regarding antibiotic resistance genes (ARGs) with respect to their potential threat to human health. Wastewater treatment plants (WWTPs) have been considered to be hotspots for ARGs. In this study, high-throughput quantitative polymerase chain reaction (HT-qPCR) was used to profile size-dependent ARGs and mobile genetic elements (MGEs) divided by particle-associated (PA) assemblages (>3.0-μm), free-living (FL) bacteria (0.2 - 3.0-μm) and cell-free (CF) DNA (< 0.2-μm) in two full-scale WWTPs (plants A and B) and a receiving stream. The results revealed that FL-ARGs were predominant in WWTPs and the receiving stream, especially in the final effluent of both plants. More than 40 types of CF-ARGs and CF-MGEs were detected with absolute abundances ranging from 6.0 ± 0.7 × 10 to 1.0 ± 0.2 × 10 copies/mL in wastewater, and relatively high abundances were also detected in the final effluent of the two plants, suggesting that CF-ARGs were important sources spreading from the WWTPs to the receiving environment. Plant A exhibited higher log-removal of size-fractionated ARGs and MGEs than was observed for plant B, which was attributed to the enhanced settleability of PA assemblages and FL bacteria by additional macrophytes and chemical coagulants. Ultraviolet disinfection had limited effects on ARGs and MGEs of the PA and FL fractions, which was probably ascribed to the protective matrices of the particles and cell walls. The bacterial communities of the two plants were significantly different among the size fractions (p < 0.01). The variation partitioning analysis (VPA) indicated that the microbial community structures and MGEs contributed a variation of 68.2% in total to the relative abundance changes of size-fractionated ARGs. Procrustes analyses and Mantel tests showed that the relative abundances of ARGs were significantly correlated with bacterial community structures. These results suggested that the bacterial community structures and MGEs might have been the main drivers of the size-fractionated ARG disseminations. This study provides novel insights into size-fractionated ARGs and MGEs in full-scale WWTPs and may lead to the identification of key targets to control the spread of ARGs.
人们对抗生素耐药基因（ARGs）对人类健康的潜在威胁表示严重关切。污水处理厂（WWTPs）被认为是 ARGs 的热点。在这项研究中，使用高通量定量聚合酶链反应（HT-qPCR）来分析大小相关的 ARGs 和移动遗传元件（MGEs），这些 ARGs 和 MGEs 按颗粒相关（PA）聚集体（>3.0-μm）、自由生活（FL）细菌（0.2-3.0-μm）和无细胞（CF）DNA（<0.2-μm）进行划分，分别在两个全规模 WWTP（工厂 A 和 B）和接收流中进行。结果表明，FL-ARGs 在 WWTP 和接收流中占主导地位，特别是在两个工厂的最终出水。在废水中检测到超过 40 种 CF-ARGs 和 CF-MGEs，其绝对丰度范围为 6.0 ± 0.7×10 到 1.0 ± 0.2×10 拷贝/ml，在两个工厂的最终出水中也检测到相对较高的丰度，表明 CF-ARGs 是从 WWTP 向接收环境传播的重要来源。与工厂 B 相比，工厂 A 对大小分馏的 ARGs 和 MGEs 的去除效果更高，这归因于附加的大型植物和化学凝结剂增强了 PA 聚集体和 FL 细菌的沉降能力。紫外线消毒对 PA 和 FL 部分的 ARGs 和 MGEs 的影响有限，这可能归因于颗粒和细胞壁的保护基质。两个工厂的细菌群落在各大小分数之间有显著差异（p < 0.01）。变异划分分析（VPA）表明，微生物群落结构和 MGEs 对大小分馏的 ARGs 相对丰度变化的贡献为 68.2%。普罗克鲁斯分析和曼特尔检验表明，ARGs 的相对丰度与细菌群落结构显著相关。这些结果表明，细菌群落结构和 MGEs 可能是大小分馏 ARG 传播的主要驱动因素。本研究为全规模 WWTP 中大小分馏的 ARGs 和 MGEs 提供了新的见解，并可能导致确定控制 ARG 传播的关键目标。
