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题名: 好氧砷还原菌的分离及其对吸附态砷迁移转化的影响
作者: 吴琼
学位类别: 硕士
答辩日期: 2013
授予单位: 中国科学院研究生院
授予地点: 北京
导师: 景传勇
关键词: ; arsenic ; 好氧砷还原菌 ; aerobic As(V)-reducing ; 解毒机制 ; bacteria ; 针铁矿 ; ars genes ; 迁移转化 ; transport ; goethite
其他题名: Characterization of Aerobic As(V)-reducing bacteria and its influence on the fate and transpot of As adsorbed on goethite
中文摘要:       砷是自然环境中一种常见元素,近年来由于饮用高砷地下水引发的地方性砷中毒现象逐渐引起人们的关注。微生物在砷的生物地球化学循环过程中具有至关重要的作用,决定砷的价态、形态、毒性及迁移转化,因而是环境科学的前沿研究热点。本文旨在:1)从典型高砷地区土壤样品中提取分离得到好氧砷还原菌株,并鉴定其种属;2)表征砷还原菌的性质、描述砷还原动力学过程,研究脱毒机理的基因机制;3)模拟地下水-土壤多介质环境中,吸附于针铁矿的砷在好氧砷还原菌作用下的价态转换及迁移过程。 首先,从从典型高砷地区土壤样品中利用传统微生物学技术分离得到高效的好氧砷还原菌株SXB和IMH,并对两株菌的性质进行表征。利用16S rDNA技术进行PCR扩增,得到二者的16S rDNA序列信息,在GeneBank中进行序列比对,得到有关菌株的种属信息。菌株SXB属于芽孢杆菌属。菌株IMH属于成团泛菌属。有关成团泛菌属的菌株具有砷还原能力的报道在国内外尚属首例。 其次,进行了两菌株砷还原性能、动力学过程和基因机制的研究。在好氧条件下,两株菌都能够在36小时内还原1 mmol/L液体培养基中超过90%的五价砷。菌株SXB是兼性菌,在好氧条件下的砷还原性能优于厌氧条件。菌株IMH是严格好氧菌。在菌株SXB和IMH中,均得到了翻译产物为三价砷排出(ArsB)离子泵的arsB基因的片段(936 bp)。在菌株SXB中得到了控制ArsC砷还原酶合成的arsC基因片段(275 bp)。在菌株IMH中得到了具体生物学功能尚不明确的arsH基因片段(502 bp)。 最后,采用固定床土柱实验,模拟地下水-土壤多介质环境,研究好氧砷还原菌SXB、砷、针铁矿三者的相互作用。探讨了在地下水环境中针铁矿对砷的吸附及对菌体生长的影响。在此基础上,设计了四组土柱实验:空白对照组、1号柱子(添加针铁矿)、2号柱子(添加砷还原菌)、3号柱子(既添加针铁矿又添加砷还原菌)。利用X射线吸收近边光谱(XANES)技术,发现菌体在还原砷的同时,对铁也存在还原作用。在四组柱子的出水中除了检出以三价砷为主的溶解态砷,还存在二价的溶解态铁。针铁矿的存在促进了铁和三价砷的溶出。菌体和针铁矿的存在能够促进可移动性更强、毒性更强的三价砷释放,加剧砷污染。
英文摘要:       Arsenic catastrophes are occurring worldwide and resulting in serious health problems in many countries. Microorganisms play an important role in the As biogeochemical cycle in the environment. The detoxification processes found in aerobic As(V)-reducing bacteria are mostly regulated via ars operons. The effects of aerobic As(V)-reducing bacteria on As fate and transport in As-contaminated environment need to be clarified. The aims of the present work were (i) to isolate and identify the culturable and effective aerobic As(V)-reducing bacteria from As-contaminated soils in Shanxi Province and Inner Mongolia; (ii) to evaluate the dynamic process of As(V)-reduction and clarify the genomic As(V) reduction mechanism of the isolated strain; (iii) to simulate the environmental process of interactions among As(V)-reducing bacteria, As(V) adsorbed on goethite, and the groundwater-soil system, to clarify the interacting mechanism and to find out the transport and fate of As and Fe.Firstly, details about sedimentary As(V)-reducing bacteria associated with high arsenic groundwater in Shanxi Province and Inner Mongolia are identified in this study. Aerobic As(V)-reducing bacteria from arsenic(As)-contaminated soils was enriched from the As-contaminated soil. Enrichment cultures were performed aerobically in TYEG medium in the presence of As(V). PCRs were adopted to obtain the 16S rDNA sequences. Strain SXB isolated from soil in Shanxi Province belongs to Bacillus genus. Strain IMH, an aerobic isolate obtained from soil in Inner Mongolia, identified as Pantoea, is reported for the first time to reduce As(V).Secondly, the dynamic process and genomic mechanism of detoxification were investigated. Both isolates could reduce over 90% As(V) in 36 h under aerobic conditions. Strain SXB isolated from soil in Shanxi Province reduced As(V) more effectively under aerobic conditions than under anaerobic conditions. Strain IMH grew and reduced As(V) strictly aerobically. Strain SXB and IMH reduce As(V) effectively under aerobic conditions via a detoxification mechanism regulated by ars operons. Putative gene fragments (936 bp) for the ArsB efflux pump gene were obtained from both strains. A 275-bp putative arsenate reductase gene was only amplified from strain SXB. A 502-bp putative arsH gene was amplified from strain IMH.Finally, column tests were adapted to simulate the environmental process. Interaction among the bacteria, goethite, arsenic, and groundwater system was investigated first to figure out the proper conditions. Four columns were set up with or without the addition of bacteria in the soil or goethite in the groundwater. The period of this test lasted for about 300 pore volume when there were As(V) detected in the effluent from the soil/goethite/bacteria column. XANES was adopted to analyze the speciation in the soil or solid phase. HPLC-AFS was used to monitor the As speciation. AAS was applied to obtain total Fe concentrations in aqueous phase. Addition of bacteria and goethite had positive effects on the leaching of As and Fe. In the leaching water phase As(III) was the main specie of As. The As(III) is more mobile than As(V). This phenomenon of more As(III) leached will have a negative effect on the As control in this environment. Fe(II) was detected in the effluents of columns with goethite added in the groundwater. Maybe the reductive environment is the proper reason of Fe(II) leaching.
内容类型: 学位论文
URI标识: http://ir.rcees.ac.cn/handle/311016/35179
Appears in Collections:环境化学与生态毒理学国家重点实验室_学位论文

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Recommended Citation:
吴琼. 好氧砷还原菌的分离及其对吸附态砷迁移转化的影响[D]. 北京. 中国科学院研究生院. 2013.
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