内蒙古河套盆地高砷含水系统的微生物特征及生物地球化学效应

发布时间：2018-04-18 18:16

本文选题：16S + rRNA　；参考：《中国地质大学(北京)》2016年博士论文

【摘要】：本研究以我国原生高砷地下水典型地区内蒙古河套盆地杭锦后旗作为研究区,将微宇宙实验与微生物分子生物学方法相结合,通过研究高砷地下水和沉积物中的微生物多样性及其群落结构特征,分析高砷含水层沉积物中的功能微生物群落,并与水文地球化学参数相结合,探讨微生物群落在高砷地下水运移富集过程中的作用机理。得到以下主要认识:(1)地下水样品的微生物多样性与砷污染水平有关,砷浓度相对较低的地下水样品的微生物多样性更大。细菌群落结构组成也随着地球化学条件(如氧化还原电位等)的变化而不同。(2)针对沉积物的高通量测序的CCA分析及beta多样性分布的聚类结果表明,取样深度、砷、硫和有机物含量等是影响沉积物细菌群落结构的主要因素;16S rRNA克隆文库结果也表明,沉积物微生物多样性随深度的增加而减小。(3)高砷含水层中的砷迁移受土著硝酸盐还原菌(如Pseudomonas sp.等)、铁还原菌(如Aquabacterium sp.、Thauera sp.、Georgfuchsia sp.、Methyloversatilis sp.、Clostridium sp.和Rhodoferax sp.等)、硫酸盐还原菌(如Spirochaetales sp.、Desulfuromonadales sp.、Geobacter sp.、Desulfobacca sp.和Desulfosporosinus sp.等)以及砷还原菌的影响。铁还原菌在氧化有机碳的同时,使铁氧化物发生还原性溶解,从而使铁氧化矿物表面的砷解放出来,促进地下水中砷的迁移。(4)沉积物中天然不稳定有机碳含量具有生物可利用性,足够支持上述微生物介导的生物化学活动。室内微宇宙实验证实,未加有机碳源的厌氧连续培养中,沉积物砷被大量释放出来,且所释放的砷以As(III)为主。(5)土著微生物对砷的归宿也有重要影响。X射线近边吸收结构分析显示,部分沉积物含有大量的与有机物和硫化物结合态的砷,且这些沉积物样品中存在大量的卤素呼吸菌Dehalococcoides和硫酸盐还原菌。在有机物存在的情况下,Dehalococcoides菌和Deltaproteobacteria的对As(V)、SO_4~(2-)和Fe(III)的还原作用可形成固态沉淀如Fe(II)-As(V)或As-S,将砷固定在黄铁矿中。(6)沉积物中存在与细胞质砷还原基因arsC(解毒)和呼吸砷还原基因arrA(呼吸)的功能基因,这些功能基因的存在促进了As(V)的还原。深层沉积物的微生物对As(V)还原作用更强,这与深层沉积物中存在异养砷还原菌(DARPs)有关,这些菌与已知的DARPs Desulfosporosinus Y5,Sulfurospirillum barnesii SES-3和Bacillus selenitireducens MLS10相似。
[Abstract]:The research on Hangjinhouqi Inner Mongolia Hetao Basin in typical regions of China native high arsenic groundwater as the research area, combining the microcosm experiments and microbial molecular biology method, through the research of high arsenic groundwater and sediment microbial diversity and community structure characteristics, analysis of high arsenic water functions of microbial communities in sediments, and combined with the hydrogeochemical parameters, to explore the mechanism of microbial communities in high arsenic groundwater migration and enrichment process. The results are as follows: (1) groundwater samples of microbial diversity associated with arsenic pollution levels, relatively low concentration of arsenic in groundwater samples of microbial diversity greater. Bacterial community composition with geochemical conditions (such as redox potential) vary. (2) for high-throughput sequencing of CCA in sediments analysis and beta diversity distribution The clustering results showed that the depth of sampling, arsenic, sulfur and organic matter content are the main factors influencing sediment bacterial community structure; 16S rRNA clone library showed that diversity increased with the depth of sediment microbial decreases. (3) high arsenic aquifers in the arsenic migration from native nitrate reducing bacteria (such as Pseudomonas sp.), iron reducing bacteria (such as Aquabacterium sp., Thauera sp., Georgfuchsia sp., Methyloversatilis sp., Clostridium sp. and Rhodoferax sp.), sulfate reducing bacteria (such as Spirochaetales sp., Desulfuromonadales sp., Geobacter sp., Desulfobacca sp. and Desulfosporosinus sp.) and arsenic reducing bacteria. The effects of iron reducing bacteria in organic oxidation carbon, iron oxide reduction of dissolved, so that the surface of the iron oxide minerals arsenic liberated, promote arsenic in groundwater migration. (4) natural sediment instability The machine has a carbon content of bioavailability, sufficient biochemical activities support the microbe mediated. Confirmed indoor microcosm experiments, anaerobic without organic carbon source in continuous culture, is a lot of arsenic in sediments released, and the release of arsenic by As (III). (5) the incidence of soil microorganisms arsenic also has an important influence on.X ray absorption near edge structure analysis showed that part of sediments contain large amounts of organic and sulfide bound with arsenic, and the sediment samples in the presence of a large number of halogen respiratory bacteria Dehalococcoides and sulfate reducing bacteria. In the presence of organic matter, Dehalococcoides bacteria and Deltaproteobacteria of As (V), SO_4~ (2-) and Fe (III) reduction can form solid precipitation such as Fe (II) -As (V) or As-S, will be fixed in the arsenic in pyrite. (6) and cytoplasmic gene arsC has original arsenic in sediments (detoxification) and respiratory arsenic Reduction of gene arrA (respiratory) genes of these genes was enhanced by the presence of As (V) reduction. The deep sediment microorganisms on As (V) reduction is stronger, arsenic reducing bacteria and heterotrophic the deeper sediments (DARPs), these bacteria with known DARPs Desulfosporosinus Y5, Sulfurospirillum barnesii SES-3 Bacillus selenitireducens and MLS10 are similar.

【学位授予单位】：中国地质大学(北京)
【学位级别】：博士
【学位授予年份】：2016
【分类号】：P641;P593

【参考文献】