瓯江下游流域河流沉积物重金属污染特征、来源及潜在生态风险评价

为了解瓯江下游流域及沿岸城郊入江河流沉积物中重金属的污染特征, 对瓯江流域下游及温州城区河流43个表层沉积物中Cr、Co、Ni、Cu、Zn、As 和Pb 共7 种重金属元素的含量特征进行分析, 比较了城郊与城区、城区入江口与城区内部之间河流沉积物重金属含量的特征及差异并探讨其污染来源。结果表明: 沉积物中7 种重金属元素的含量由高到低依次为: Zn>Cr>Cu>Ni>Pb>Co>As, 与浙江省土壤背景值相比, 7 种重金属的平均含量超标1.5-4.9 倍,各种重金属的污染程度依次为: Co>Ni>Cr>Zn>As>Cu>Pb, 综合污染程度已达到警戒线等级。来源分析表明, 重金属元素Cu、Zn、Pb 和Cr 主要来自于工业污水排放及船舶交通等人类活动, Co 和As 主要来自于工业及农业生产活动, Ni主要来自于以工业为主的排污污染。潜在生态风险系数Eri 评价结果显示, 7 种重金属潜在生态风险大小为:Co>As>Cu>Ni>Pb>Cr>Zn, Co 元素处于较强生态风险等级; 潜在生态风险指数RI 介于72.05-107.80 之间, 其中55.5%的样点处于较强生态风险水平, 44.4%为中等生态风险水平, 研究区整体处于较强生态风险水平。     

气溶胶中抗生素抗性基因研究进展

抗生素的不合理使用导致细菌耐药问题日趋严峻,给人类健康造成巨大威胁。学者们对抗生素抗性菌和抗生素抗性基因(antibiotic resistance genes, ARGs)在多种环境介质中的环境行为开展了大量研究。气溶胶作为ARGs的潜在储存库,是抗生素抗性基因在环境中的重要传播途径之一。目前缺乏对其来源、传播、人类接触和健康风险系统性的梳理。本文针对人类生活功能场所、养殖场、城市污水处理厂和医院等4类气溶胶研究的典型场所,重点综述了上述4类典型场所中气溶胶ARGs的来源、传播途径及对人体的暴露和对健康的危害,为气溶胶中ARGs的预防和控制提供参考。     

抗生素抗性基因的生态风险研究进展

自抗生素被发现和使用以来,其在人类和动物疾病预防与治疗、提高动物生产等方面均发挥了重要作用。但抗生素的批量生产及大量应用,特别是在养殖业和临床医疗上的滥用,导致抗生素抗性基因(ARGs)在环境中普遍存在,其借助质粒、转座子、整合子等可移动元件通过接合、转座、转化等方式在环境中广泛传播,导致微生物药性不断增强,对人类健康和生态安全造成严重威胁。当前,ARGs对人类健康的影响已受到高度关注,但有关ARGs在环境中的生态风险研究还相对薄弱。本文综述了ARGs污染的现状及其生态风险,并对该领域中未来研究重点进行了展望,以期为今后抗性基因的研究和生态防控提供参考。     

活性污泥抗生素抗性基因研究进展

抗生素抗性在全球范围内的传播扩散严重威胁人类健康。活性污泥是污水处理系统重要的处理工艺,同时也是抗生素抗性及其发生水平基因转移的一个重要储库和热区。目前,随着研究手段和技术的不断更新,活性污泥中抗生素抗性的研究不断增加,但是仍有许多科学问题亟待解决。本文主要针对活性污泥抗生素抗性的5个主要方面进行深入讨论:(1)活性污泥中抗性基因的丰度和分布的影响因素;(2)污泥抗性基因的研究方法;(3)活性污泥抗性基因的传播与扩散;(4)污泥中抗性基因环境风险评估;(5)研究展望。本综述在活性污泥抗生素抗性研究基础上,阐述了驱动抗生素抗性扩散的基本微生物生态过程研究进展,旨在为污水处理工艺的发展和优化及抗性基因控制政策的制定提供科学基础。     

重金属污染土壤中细菌抗生素抗性基因分布特征

重金属作为常见的土壤污染物,可通过共选择作用诱导土壤微生物群落的抗生素抗性基因(antibioticresistancegenes,ARGs)的产生和扩散,并促进ARGs在环境中持久存在。本研究建立了不同铜(Cu)浓度和镉(Cd)浓度的土壤微宇宙实验,基于高通量测序和实时荧光定量PCR技术分析不同重金属浓度和复合污染条件下ARGs的分布特征以及土壤细菌群落对不同浓度Cu、Cd污染的响应,旨在解析ARGs与土壤细菌群落在重金属污染土壤中的分布特征。此外,通过探究影响ARGs变化的关键环境因子,以期找出有效减缓环境中抗生素抗性的传播和扩散现状的途径。研究表明:高浓度Cu(400 mg/kg)与Cd(1 mg/kg和5 mg/kg)的复合污染显著(P <0.05)提高了土壤中抗生素抗性基因sul1、intl1、bla VIM的相对丰度,抗生素抗性基因tet X、tet G对Cd响应最敏感,低浓度Cd (1 mg/kg)可明显提高tet X、tet G的丰度。此外, Cu、Cd显著(P <0.05)改变了土壤细菌群落结构,并且使细菌群落对Cu的响应更加明显。相关性分析和网络分析表明,sul1、tet X、tet M02、bla VIM广泛分布在多个细菌门,而ARGs的变化与细菌群落(如链霉菌属Streptomyces、慢生根瘤菌属Bradyrhizobium、BIrii41属(Polyangiales)、海无柄孢囊黏细菌属Haliangium等)的变化密切相关,推测这些细菌可能是携带ARGs的主要宿主。     

卫生填埋场微生物气溶胶的逸散及潜在风险

随着对微生物气溶胶认识的提高,其产生、来源、扩散及风险研究获得了越来越多的关注。卫生填埋场是微生物气溶胶的重要产生源之一。本文阐述了卫生填埋场气溶胶颗粒中微生物的浓度水平、粒径分布、种群结构,解析了微生物气溶胶的逸散特征及影响因素,介绍了微生物气溶胶对人体健康的潜在风险及评价方法,并展望了未来卫生填埋场逸散微生物的研究趋势及方向,为卫生填埋场微生物气溶胶的控制与削减提供了科学依据和参考。     

自然曝气生物滤床对二级污水处理厂尾水中抗生素的去除效果及影响因素研究

采用自然曝气生物滤床工艺处理污水处理厂尾水中抗生素,对生物滤床中抗生素的去除特点和影响因素进行研究。研究结果发现,自然曝气生物滤床能够有效地去除四环素类抗生素(58±2)%、喹诺酮类抗生素(48±20)%和大环内酯类抗生素(18±11)%。微生物降解和物理吸附是生物滤床去除抗生素的主要途径,而这两种途径的协同作用则延长了生物滤床的运行周期。结果还表明,水力负荷对抗生素的去除效率影响较大,当水力负荷为4.8～6.4m/d时,生物滤床对抗生素有较好的处理效果。此外,水质参数(水温、pH、COD浓度和硝化作用等)在一定程度上也可以影响生物滤床对抗生素的处理效果。     

西安城市路边土壤重金属来源与潜在风险

应用X-Ray荧光光谱仪对西安城市路边土壤重金属含量进行测定,运用相关分析、主成分分析和聚类分析探讨了路边土壤的重金属来源,并利用潜在生态风险指数法评价了其生态风险.结果表明:西安城市路边土壤中Co、Cr、Cu、Mn、N、iPb和Zn的平均含量均高于陕西土壤背景值.路边土壤中As、Mn和N i主要来自于自然源和交通源,Cu、Pb和Zn主要来自交通源,Co和Cr主要来源于工业源.潜在生态风险评价结果显示,西安城市路边土壤中重金属元素属于中等污染程度,具有中等潜在生态风险.     

污水处理厂中四环素和磺胺类抗生素抗性基因的分布、传播及去除

近年来,抗生素滥用造成的抗性基因(ARGs)污染问题引起了人们的关注.四环素及磺胺类抗生素由于价格低廉被广泛使用,大量残留的四环素和磺胺通过各种途径进入污水处理厂,并进一步导致ARGs的污染.为深入了解四环素和磺胺类ARGs的污染及治理现状,本研究对污水处理厂中四环素和磺胺类ARGs的分布情况及传播机制进行了综述,并重点讨论了不同污水处理工艺对ARGs的去除效果.在此基础上,从加大污水处理厂ARGs污染调查、改进污水处理工艺以及探讨ARGs传播机制等方面进行了展望.     

人为源微生物气溶胶的分布特征及风险研究进展

近年来,新型冠状病毒肺炎疫情全球肆虐,引起了公众对于微生物气溶胶潜在风险的极大关注,其中人为源微生物气溶胶潜在的健康危害逐步成为越来越多学者关注的热点之一。本文综述了近年来4类主要人为源微生物气溶胶的研究现状,比较了不同人为源微生物气溶胶的分布特征和微生物组成特性,并探究了影响微生物气溶胶特征的主要因素及其存在的潜在风险。结果表明,畜禽养殖场微生物气溶胶平均浓度最高,其次是污水处理厂和垃圾填埋场,医院最低。从微生物组成特性来说,不同人为源微生物气溶胶中微生物组成与其产生源密切相关;同时,其组成也受其所处环境条件影响。基于以上分析,本文进一步展望了未来人为源微生物气溶胶的主要研究方向,以期为微生物气溶胶控制标准的制定及控制技术的研发奠定基础。     

Quantitative and qualitative impact of hospital effluent on dissemination of the integron pool

There is increasing evidence that human activity, and especially the resulting effluent, has a major role in the dissemination of bacterial antibiotic-resistance determinants in the environment. Hospitals are the major antibiotic consumers and thus facilitate the spread of antibiotic resistance. Questions are increasingly being raised about the management of hospital effluents, but their involvement in antibiotic-resistance dissemination has never been assessed. Integrons are a paradigm of genetic transfer between the environmental resistome and both commensal and pathogenic bacteria. In order to assess the impact of hospital activities on antibiotic-resistance dissemination in the environment, we monitored integrons and their gene cassettes in hospital effluents, and their release in the environment. We found that bacterial communities present in a hospital effluent contained a high proportion of integrons. In terms of both their gene cassette diversity and gene cassette arrays, the urban effluent and municipal wastewater treatment plant (WWTP) influent were most similar, whereas the hospital effluent and recirculation sludge exhibited very specific patterns. We found that anthropogenic activities led to the release of abundant integrons and antibiotic-resistance gene cassettes, but we observed no specific impact of hospital activities on the receiving environment. Furthermore, although the WWTP did not reduce the normalized integron copy number, it reduced the diversity of gene cassette arrays contained in the raw wastewater, underlining the effect of the biological treatment on the anthropogenic integron pool arriving at the WWTP.     

Antibiotic resistance of enterococci and related bacteria in an urban wastewater treatment plant

The main objective of this work was to study the ecology of enterococci and related bacteria in raw and treated wastewater from a treatment plant receiving domestic and pretreated industrial effluents in order to assess the influence of treatment on the prevalence of antibiotic resistance phenotypes among this group of bacteria. The predominant species found in the raw wastewater were Entercoccus hirae, Entercoccus faecium and Entercoccus faecalis. Wastewater treatment led to a reduction in E. hirae (alpha<0.1) and an increase in E. faecium (alpha<0.1); the relative proportions of E. faecalis remained the same in the raw and in the treated wastewater. Among the isolates tested, no vancomycin resistance was observed among the enterococci. Entercoccus faecium and E. faecalis showed resistance prevalence values reaching 33%, 40% and 57% for the antibiotics ciprofloxacin, erythromycin and tetracycline, respectively. Antibiotic-resistant strains of enterococci were not eliminated by wastewater treatment. A positive selection of ciprofloxacin-resistant enterococci was indicated by a significant increase in resistance prevalence (alpha<0.02) in treated wastewater compared with the raw wastewater.     

Comparison of Salmonella enterica serovar distribution and antibiotic resistance patterns in wastewater at municipal water treatment plants in two California cities

AIM: To determine Salmonella enterica serovars and antibiotic resistance (ABR) in the human waste stream. METHODS AND RESULTS: Sampling of influent wastewater at municipal treatment plants in two California cities was performed by collecting composite samples, over a 24-h period, from the treatment plants on five to six occasions. Serial water quantities were filtered and cultured with a Salmonella selective method and an oxytetracycline-supplemented Salmonella selective method. Antibiotic susceptibilities to 12 antibiotics were determined and the isolates were grouped based on ABR patterns. From 983 S. enterica isolated, 102 represented unique sampling-serovar-ABR patterns. Thirty-five different serovars were identified to be distributed over 17 different ABR patterns. The serovar distribution differed between the sampling sites, whereas there was no significant trend in levels of multiple ABR. CONCLUSIONS: Salmonella enterica was recovered with ease from small sample volumes of wastewater received by municipal water treatment plants. A large variety of serovars and ABR profiles were represented in the recovered Salmonella. SIGNIFICANCE AND IMPACT OF THE STUDY: The ease of sampling and recovery of Salmonella from municipal wastewater from treatment plants makes it a valuable sampling approach for monitoring the presence of Salmonella in the human population.     

An evaluation of survival and detection of Campylobacter jejuni and C. coli in broiler caecal contents using culture‐based methods

Aims: (i) To cultivate methicillin‐resistant Staphylococcus aureus (MRSA) from a full‐scale wastewater treatment plant (WWTP), (ii) To characterize the indigenous MRSA‐flora, (iii) To investigate how the treatment process affects clonal distribution and (iv) To examine the genetic relation between MRSA from wastewater and clinical MRSA. Methods: Wastewater samples were collected during 2 months at four key sites in the WWTP. MRSA isolates were characterized using spa typing, antibiograms, SSCmec typing and detection of Panton–Valentine leukocidin (PVL). Conclusions: MRSA could be isolated on all sampling occasions, but only from inlet and activated sludge. The number of isolates and diversity of MRSA were reduced by the treatment process, but there are indications that the process was selected for strains with more extensive antibiotic resistance and PVL+ strains. The wastewater MRSA‐flora had a close genetic relationship to clinical isolates, most likely reflecting carriage in the community. Significance and Impact of the Study: This study shows that MRSA survives in wastewater and that the WWTP may be a potential reservoir for MRSA.     

植物在水产养殖废水处理中的研究进展

植物在生长繁殖过程中能吸收利用、富集、吸附和固定水产养殖水体中的有机物、无机物和重金属,降低养殖水体中的TP、TN、TSS、COD和BOD。同时,植物在水体中可通过其发达的通气组织和根系传输氧气,为微生物和其他生物的代谢活动提供适宜的条件。选择合适的植物构建人工湿地,通过人工湿地中植物、微生物和基质的物理作用、化学作用和生物作用处理水产养殖废水,可建立循环的水产养殖模式。将植物应用于水产养殖废水的处理,是实现可持续发展的生态型水产养殖的基础。本文综述了近年来藻类和高等植物在水产养殖废水处理中的研究进展。     

Determining the limits of the evolutionary potential of an antibiotic resistance gene

The AAC(6') enzymes inactivate aminoglycoside antibiotics by acetylating their substrates at the 6' position. Based on functional similarity and size similarity, the AAC(6') enzymes have been considered to be members of a single family. Our phylogenetic analysis shows that the AAC(6') enzymes instead belong to three unrelated families that we now designate as [A], [B], and [C] and that aminoglycoside acetylation at the 6' position has evolved independently at least three times. AAC(6')-Iaa is a typical member of the [A] family in that it acetylates tobramycin, kanamycin, and amikacin effectively but acetylates gentamicin ineffectively. The potential of the aac(6')-Iaa gene to increase resistance to tobramycin, kanamycin, or amikacin or to acquire resistance to gentamicin was assessed by in vitro evolution. Libraries of PCR mutagenized alleles were screened for increased resistance to tobramycin, kanamycin, and amikacin, but no isolates that conferred more resistance than the wild-type gene were recovered. The library sizes were sufficient to conclude with 99.9% confidence that no single amino acid substitution or combination of two amino acid substitutions in aac(6')-Iaa is capable of increasing resistance to the antibiotics used. It is therefore very unlikely that aac(6')-Iaa of S. typhimurium LT2 has the potential to evolve increased aminoglycoside resistance in nature. The practical implications of being able to determine the evolutionary limits for other antibiotic resistance genes are discussed.     

抗生素耐药性的多重风险因子及针对性管控策略

抗生素耐药性已经对人类社会造成了重大影响,需要采取切实有效的管控措施,本文将针对耐药性研究领域的新视角,回顾了亟需重视的抗生素耐药性多重风险因素,包括非致病菌、食源和肠道菌群、粪便菌群、废水处理、用药途径和生物膜等,强调了口服抗生素的危害。通过总结针对性的耐药和疾病防控策略,为有效应对抗生素耐药性危机提供新思路。