摘要

       水资源回收设施被描述为为各种细菌中抗生素抗性基因 (ARG) 的选择、转移和传播创造了温床条件。本研究的目的是确定直接添加抗生素和银纳米粒子（Ag NPs 或纳米银）对嗜热厌氧消化器中 ARG 发生的影响。使用环境相关浓度的 Ag NP（0.01、0.1 和 1.0 mg-Ag/L；对应于 ≈0.7、7.0 和 70 mg-Ag/kg 总固体）和磺胺甲恶唑 (SMX) 对测试嗜热消化器进行了修正。易受抗性分类（1、5 和 50 毫克/升）作为 ARG 的潜在选择压力。四环素（tet(O)、tet(W)）和磺胺（sulI、sulII）ARGs 和与 1 类整合子相关的整合酶基因 (intI1) 在原料污泥、测试高温消化器、对照高温消化器和一个控制中温消化池。 Ag NPs 对嗜热厌氧消化池性能没有明显影响。最大 SMX 添加量 (50 mg/L) 导致挥发性脂肪酸的积累和低 pH 值、碱度和挥发性固体减少。在改良的嗜热消化器和对照嗜热消化器中，ARG 基因拷贝数（绝对或标准化为 16S rRNA 基因）之间没有显着差异。由于 ARGs 减少 1-log（intI1 减少 2-log），消化污泥中抗生素抗性基因拷贝数范围为 103 至 106 拷贝/μL（≈8 × 101 至 8 × 104 拷贝/μg）。原始污泥中五种 ARG 的数量范围为每微升污泥 104 至 108 份（≈4 × 102 至 4 × 106 每微克）。测试和对照嗜热消化器（53 °C，12 天固体保留时间 [SRT]）持续降低但并未消除所有分析基因的水平。中温消化器（37 °C，20 天 SRT）也降低了 sulI、sulII 和 intI1 基因的水平，但 tet(O) 和 tet(W) 的水平与生污泥相同或更高。尽管应用了选择压力，抗生素抗性基因的减少仍然保持不变，这表明消化器的运行条件是细菌群落组成以及 ARG 流行的重要控制因素。

       Water resource recovery facilities have been described as creating breeding ground conditions for the selection, transfer, and dissemination of antibiotic resistance genes (ARGs) among various bacteria. The objective of this study was to determine the effect of direct addition of antibiotic and silver nanoparticles (Ag NPs, or nanosilver) on the occurrence of ARGs in thermophilic anaerobic digesters. Test thermophilic digesters were amended with environmentally-relevant concentrations of Ag NP (0.01, 0.1, and 1.0 mg-Ag/L; corresponding to ≈0.7, 7.0, and 70 mg-Ag/kg total solids) and sulfamethoxazole (SMX) that span susceptible to resistant classifications (1, 5, and 50 mg/L) as potential selection pressures for ARGs. Tetracycline (tet(O), tet(W)) and sulfonamide (sulI, sulII) ARGs and the integrase enzyme gene (intI1) associated with Class 1 integrons were measured in raw sludge, test thermophilic digesters, a control thermophilic digester, and a control mesophilic digester. There was no apparent effect of Ag NPs on thermophilic anaerobic digester performance. The maximum SMX addition (50 mg/L) resulted in accumulation of volatile fatty acids and low pH, alkalinity, and volatile solids reduction. There was no significant difference between ARG gene copy numbers (absolute or normalized to 16S rRNA genes) in amended thermophilic digesters and the control thermophilic digester. Antibiotic resistance gene copy numbers in digested sludge ranged from 103 to 106 copies per μL (≈8 × 101 to 8 × 104 copies per μg) of sludge as result of a 1-log reduction of ARGs (2-log reduction for intI1). Quantities of the five ARGs in raw sludge ranged from 104 to 108 copies per μL (≈4 × 102 to 4 × 106 per μg) of sludge. Test and control thermophilic digesters (53 °C, 12-day solids retention time [SRT]) consistently reduced but did not eliminate levels of all analyzed genes. The mesophilic digester (37 °C, 20-day SRT) also reduced levels of sulI, sulII, and intI1 genes, but levels of tet(O) and tet(W) were the same or higher than in raw sludge. Antibiotic resistance gene reductions remained constant despite the application of selection pressures, which suggests that digester operating conditions are a strong governing factor of the bacterial community composition and thus the prevalence of ARGs.

https://onlinelibrary.wiley.com/doi/abs/10.2175/106143012X13373575831394