Department of Civil and Environmental Engineering, Duke University, Box 90287, Durham, NC 27708, United States; Center for Environmental Implications of NanoTechnology (CEINT), Duke University, Durham, NC 27708, United States; Department of Civil and Environmental Engineering, Bucknell University, 1 Dent Drive, Lewisburg, PA 17837, United States.
Department of Civil and Environmental Engineering, Duke University, Box 90287, Durham, NC 27708, United States.
Sci Total Environ. 2018 Mar;616-617:1014-1021. doi: 10.1016/j.scitotenv.2017.10.217. Epub 2017 Nov 6.
Silver nanoparticles (AgNPs), which are known to act as biocides, are incorporated into medical and consumer products including athletic clothing, stuffed animals, liquid dietary supplements, and more. The increasing use of AgNPs in these products is likely to lead to their entry into both natural and engineered systems, which has the potential to disrupt bacterial processes including those involved in nutrient cycling in wastewater treatment. In the present study, sequencing batch reactors (SBR) mimicking secondary wastewater treatment were operated to determine the effects of AgNPs on the microbial communities contained within activated sludge of wastewater treatment plants (WWTP). SBRs were treated with 0.2 and 2ppm of either gum Arabic (GA)-coated AgNPs, citrate (Ca)-coated AgNPs, or Ag as AgNO. Cell samples were collected and DNA isolated periodically throughout SBR operation. DNA was used for Ion Torrent Next Gen Sequencing of the V3 region of the 16S rDNA gene. Subsequent analyses revealed that the microbial community both shifted and recovered quickly in response to Ag. Both AgNP treatments resulted in slower initial community shifts than that observed with the Ag treatment. GA-AgNPs elicited the longest lasting effect. Additional examination of nitrogen removal bacteria suggested the possibility of an increase in sludge bulking species with increased concentrations of AgNPs in WWTPs. This study supports the hypothesis that Ag release from AgNPs is largely coating-dependent and thus a key driver in dictating AgNP toxicity.
银纳米粒子（AgNPs）作为杀菌剂，被广泛应用于医疗和消费品领域，包括运动服装、填充动物玩具、液体膳食补充剂等等。AgNPs 在这些产品中的应用日益广泛，可能会导致它们进入自然和人工系统，从而有可能破坏细菌的代谢过程，包括废水处理中涉及的营养物质循环过程。在本研究中，我们采用模拟二级废水处理的序批式反应器（SBR）来确定 AgNPs 对污水处理厂活性污泥中微生物群落的影响。SBR 分别以 0.2ppm 和 2ppm 的浓度添加阿拉伯胶（GA）包覆的 AgNPs、柠檬酸盐（Ca）包覆的 AgNPs 或 Ag 作为 AgNO3 进行处理。在 SBR 运行过程中定期采集细胞样本并提取 DNA。使用 Ion Torrent Next Gen 测序技术对 16S rDNA 基因的 V3 区进行测序。随后的分析表明，微生物群落对 Ag 的响应迅速发生了变化和恢复。与 Ag 处理相比，两种 AgNP 处理导致初始群落变化较慢。GA-AgNPs 产生的影响持续时间最长。对氮去除细菌的进一步研究表明，随着 AgNPs 在 WWTP 中浓度的增加，可能会增加污泥膨胀物种的数量。本研究支持 Ag 从 AgNPs 中的释放主要取决于涂层的假说，因此是决定 AgNP 毒性的关键因素。
