【作者】 王钰；

【导师】 白晓慧；

【作者基本信息】 上海交通大学 ， 生物工程（专业学位）， 2018， 硕士

【摘要】 对于饮用水中的微生物污染,绝大多数研究集中在细菌、病毒及原虫和蠕虫,而对于真菌的研究较少。真菌中包含多种潜在致病菌,应当引起人们的关注。本研究以华东某市供水系统(2017前以HPJ为原水、2017年后以JZ水库为原水)为研究对象,将城市供水系统分为原水、净水工艺、管网及二次供水四个部分。(1)基于ITS1区高通量测序技术,分析了城市供水系统对真菌菌群结构的影响。研究表明:子囊菌门在供水系统中为优势菌门,但不同的原水、净水工艺和末端用户水之间优势菌属各有不同;曲霉属真菌存在于供水系统所有样本之中,表明此菌属能够穿透供水系统过程的多级屏障,现有净水工艺无法将其有效去除;同时还发现供水系统中存在潜在条件致病真菌(青霉属Penicillium、枝孢霉属Cladosporium、曲霉属Aspergillus、支顶孢属Acremonium、假丝酵母菌属Candida、镰刀霉属Fusarium、链格孢属Alternaria)。(2)采用平板培养法和荧光定量PCR技术,观察了城市供水系统中真菌数量的动态变化。研究表明:原水经过净水工艺处理后,水中真菌数量能够得到有效控制;净水工艺中生物活性炭滤池出水的真菌数量比前一工艺单元有所升高,存在真菌泄漏现象。经过供水管网输配和二次供水设施后,末端用户水中真菌数量升高;特别是经过二次供水水箱水泵系统后,真菌数量会出现大幅上升,明显高于直供水模式。供水管网及二次供水设施是末端饮用水中真菌污染的重要来源,二次供水模式应尽量减少中间停滞环节以控制供水管网中真菌的再生风险。荧光定量qPCR与平板培养计数法检测真菌数量的结果之间正相关性良好。(3)对供水系统中的真菌进行分离纯化,研究了氯消毒对饮用水中潜在条件致病真菌灭活的效能与机制。研究结果表明:在供水系统中分离纯化得到黄曲霉(Aspergillus flavus),该菌是能够穿透供水系统多级屏障的曲霉属真菌中最为重要的致病性真菌之一。一氯胺处理黄曲霉孢子的过程中,随着反应时间的延长,黄曲霉的灭活率呈现升高趋势;在处理时间相同时,不同初始浓度的氯灭活效果存在差异,浓度越大,灭活效果越好。拟合三种动力学模型后发现Hom模型能较好的阐释一氯胺灭活真菌孢子的消毒特性。通过测定黄曲霉孢子表面疏水率,发现黄曲霉具有较强的耐氯能力,但氯胺也能够对黄曲霉孢子细胞膜产生破坏作用。更多还原

【Abstract】 The majority of studies on microbial contamination in drinking water focuses more on bacteria,viruses,protozoa and worms,but less on fungi.We should also pay attention to fungi that contain a variety of potential pathogenic groups.In this study,the water supply system,which takes the upstream water of HPJ and water of JZ Reservoir as the raw water,was used as the research object.The urban water supply system was divided into four parts:raw water,water works,water supply pipelines and secondary water supply.(1)The effects of urban water supply system on fungal community structure were analyzed by using ITS1 high-throughput sequencing technology.The results showed the dominance of Ascomycota in Minhang water supply system and fungal genera such as Aspergillus were present in all samples but rest were varied from samples to samples.Aspergillus can penetrate multi-stage barriers in the process of water supply system and potentially pathogenic fungi that can cause infections existed in water supply systems(Penicillium,Cladosporium,Aspergillus,Acremonium,Candida,Fusarium,Alternaria).(2)The dynamic changes of fungal population were detected by culture method and real-time quantitative PCR technology.The results showed the fungal population were greatly reduced after treated by water purification process.The population richness of fungi rose after filtering by activated carbon,which can lead a fungus leakage.After passing through water supply pipelines and secondary water supply facilities,tap water sample showed significantly higher data in the quantity of fungi than effluent water.Water supply pipelines and secondary water supply facilities are important sources of fungal contamination in tap water.The secondary water supply should minimize intermediate stagnation to control the risk of fungal regeneration in the water supply system.There is a good positive correlation between the results of qPCR and plate culture results.(3)To explore the efficiency and mechanism of chlorine disinfection on potential pathogenic fungi strain in drinking water,fungi strain were isolated and identified from urban water supply system.Aspergillus flavus isolated from the water supply system is one of the most important pathogenic fungi in Aspergillus that can penetrate the multi-stage barrier of the water supply system.During the treatment of Aspergillus flavus spores by monochloramine,the inactivation rate of spores showed an increasing trend with the extension of reaction time and when the treatment time was the same,the inactivation effect of chlorine at different initial concentrations was different.Hom model is the best model to fit the inactivation characteristics of Aspergillus flavus spores.Aspergillus flavus spores were found with strong chlorine resistance by measuring the cell surface hydrophobicity(CSH).It was verified that chlorine can destroy the membrane of Aspergillus flavus spores.更多还原