摘要

    废水和污水处理厂（WWTP）包含多种抗生素抗性基因（ARG），可通过排放废水而将其传播到环境中（Szczepanowski等，2009； Berendonk等，2015； Chu等， 2018;彼得罗维奇（Petrovich）等人，2018）。人们认为医院废水是选择污水处理厂ARG的一个特别重要的驱动因素，因为医院废水中通常含有比其他城市废水源更高浓度的抗药性细菌和抗生素残留物（Baquero等人，2008； Rodriguez-Mozaz等人，2015）。 ）。由于医院废水还包含抗生素和其他药物等化学物质，碘化X射线造影剂和对环境构成威胁的消毒剂的混合物，因此，考虑将医院废水的单独处理作为市政废水处理的替代方法或补充（Ternes等人，2004； Pauwels和Verstraete，2006； Szekeres等人，2017）。尽管在大多数情况下，医院污水仍在市政污水处理厂中处理，但单独的处理系统为针对这种特定类型的进水实施专门流程提供了机会（Pauwels和Verstraete，2006； Hocquet等，2016）。这在以色列尤为重要，在以色列，废水用于景观和农作物灌溉的再利用是水可持续性不可或缺的一部分-超过85％的废水回用于灌溉，而农业用水约40％来自经处理的废水（IWA，2011年） ; Reznik et al。，2017）。先前的工作表明，处理过的城市废水中的ARG负荷对本地土壤微生物群的影响可能不大（Negreanu等，2012； Gatica和Cytryn，2013）。但是，分散的医院废水处理方案尚未充分表征与临床相关抗生素相对应的ARGs的多样性和命运，这阻碍了与现场处理以及处理后废水的再利用或释放相关的公共卫生风险的管理。

相对于污水处理基础设施中的微生物种群，病毒群落的研究远远不足。尽管一些研究已经分析了大规模市政污水处理厂和生物固体中的病毒（Rosario等，2009； Bibby和Peccia，2013），但现场医院废水处理系统中的病毒多样性，社区组成和命运仍然不尽人意了解。研究表明，废水中含有多种人类和其他来源的病毒（Wu和Liu，2009； Tamaki等，2012； Aw等，2014）。噬菌体是废水中最常见的病毒，废水中也普遍存在人类病原体，例如腺病毒和甲型肝炎病毒（Prado等，2011； Aw等，2014）。用于中水回用的再生水每单位体积比饮用水中含有数千个病毒样颗粒（Rosario等，2009）。因此，与饮用水相比，用于现场灌溉再利用的经过处理的医院废水也可能含有较高的病毒载量。此外，先前的研究表明病毒是否与ARGs显着相关并因此可以促进其在细菌之间的转移存在矛盾的结果（Zhang and LeJeune，2008; Colomer-Lluch et al。，2014; Enault et al。，2017）。

在这里，我们专注于位于以色列特拉维夫的Tel HaShomer医院的独特的中试规模医院废水处理系统。该系统在天然淡水资源有限且必须对废水进行适当处理的城市地区，面临着制药和遗传污染物水平升高的问题，从而面临废水污染的挑战。中试规模的系统处理医院废水的目的是最终使用处理后的废水在医院现场灌溉园林绿化。这项研究的目的是调查整个试验规模的医院污水处理厂系统中的ARG和dsDNA病毒的丰度，多样性，基因组背景和命运，以及分析相应的细菌群落结构。我们假设医院废水中高水平的抗生素抗性细菌会促进整个处理系统中多个ARG的持久性，但相继的二级处理过程可减少废水中的ARG负荷。我们还假设病毒群落可能是系统中ARG的重要载体。这项工作对医院废水的ARG和病毒含量及其如何可能影响接收医院出院废水的环境提供了重要的见解。

    Wastewater and wastewater treatment plants (WWTPs) contain a variety of antibiotic resistance genes (ARGs) that can be transmitted into the environment through the discharge of effluents (Szczepanowski et al., 2009; Berendonk et al., 2015; Chu et al., 2018; Petrovich et al., 2018). Hospital wastewater is thought to be a particularly important driver of selection for ARGs in WWTPs because it often contains antibiotic resistant bacteria and antibiotic residues at higher concentrations than other urban wastewater sources (Baquero et al., 2008; Rodriguez-Mozaz et al., 2015). Since hospital wastewater also contains a mixture of chemicals such as antibiotics and other pharmaceuticals, iodinated X-ray contrast media, and disinfectants that pose environmental threats, separate treatment of hospital wastewater has been considered as an alternative or in addition to municipal wastewater treatment (Ternes et al., 2004; Pauwels and Verstraete, 2006; Szekeres et al., 2017). While in the majority of cases hospital wastewater is still treated in municipal WWTPs, separate treatment systems offer opportunities to implement specialized processes for this particular type of influent (Pauwels and Verstraete, 2006; Hocquet et al., 2016). This is especially relevant in Israel, where wastewater reuse for landscape and crop irrigation is an integral part of water sustainability—over 85% of wastewater effluent is reused for irrigation and around 40% of water used in agriculture comes from treated wastewater (IWA, 2011; Reznik et al., 2017). Previous work has suggested that the influence of ARG loading from treated municipal wastewater on native soil microbiomes may not be significant (Negreanu et al., 2012; Gatica and Cytryn, 2013). However, diversity and fate of ARGs corresponding to clinically relevant antibiotics has not been thoroughly characterized in decentralized hospital wastewater treatment schemes, which impedes management of public health risks associated with onsite treatment and reuse or release of treated wastewater.

Viral communities are vastly understudied relative to their microbial counterparts in wastewater treatment infrastructure. While some research has analyzed viruses in full-scale municipal WWTPs and in biosolids (Rosario et al., 2009; Bibby and Peccia, 2013), viral diversity, community composition, and fate in on-site hospital wastewater treatment systems is not yet well understood. Research has demonstrated that wastewater contains a wide assortment of viruses from humans and other sources (Wu and Liu, 2009; Tamaki et al., 2012; Aw et al., 2014). Bacteriophages are the most common type of virus in wastewater, and human pathogens such as adenoviruses and hepatitis A viruses are also prevalent in wastewater (Prado et al., 2011; Aw et al., 2014). Reclaimed water for water reuse applications has thousands more virus-like particles per unit volume than potable water (Rosario et al., 2009). Thus, treated hospital wastewater intended for on-site irrigation reuse may also contain high viral loads compared to potable water. Furthermore, previous studies have shown conflicting results on whether or not viruses are significantly associated with ARGs and thus can facilitate their transfer between bacteria (Zhang and LeJeune, 2008; Colomer-Lluch et al., 2014; Enault et al., 2017).

Here, we focus on a unique, pilot-scale hospital wastewater treatment system located at the Tel HaShomer Hospital in Tel Aviv, Israel. This system confronts the challenge of wastewater contamination with enhanced levels of pharmaceuticals and genetic pollutants in an urban region where natural freshwater sources are limited and appropriate treatment of wastewater is imperative. The pilot-scale system treats hospital wastewater with the intent to eventually use the treated wastewater to irrigate landscaping on-site at the hospital. The objectives of this study were to investigate ARG and dsDNA viral abundances, diversity, genomic context, and fate throughout the pilot-scale hospital WWTP system, as well as to analyze corresponding bacterial community structure. We hypothesized that high levels of antibiotic-resistant bacteria in hospital wastewater facilitate persistence of multiple ARGs throughout the treatment system, yet sequential secondary treatment processes act to reduce ARG loading in effluent. We also hypothesized that the viral community could be a significant vector for ARGs in the system. This work provides important insights into the ARG and viral content of hospital wastewater and how it can potentially impact environments that receive discharged hospital effluent.

    https://www.frontiersin.org/articles/10.3389/fmicb.2020.00153/full?utm_source=S-TWT&utm_medium=SNET&utm_campaign=ECO_FCIMB_XXXXXXXX_auto-dlvrit