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首页> 外文学位 >Molecular biodiversity of microbial communities in polluted soils and their role in soil phytoremediation.
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Molecular biodiversity of microbial communities in polluted soils and their role in soil phytoremediation.

机译：污染土壤中微生物群落的分子生物多样性及其在土壤植物修复中的作用。

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摘要

Trace metals (TM) are continually world-wide added to soils through the intensive use of mineral fertilizers and agriculture chemicals, together with industrial and other activities generating toxic wastes. Problems associated with metal-contaminated soil exists because TM are not biodegradable. TM that accumulate in soils affect the biodiversity of soil microorganisms.;Nitrogen (N) fertilization is a widespread practice to increase soil fertility and crop production. However, the long-term use of N fertilization causes many detrimental effects in the environment. The intensive use of N fertilization increase TM input in soils, and in extreme cases, N fertilization result in TM pollution of the surrounding soil and water and increase TM concentration in plant tissues. In addition, the long-term use of N fertilizers changes and declines the biodiversity of above and underground ecosystems.;The community structure of arbuscular mycorrhizal fungi (AMF) was investigated in TM contaminated and long-term N fertilized soils. In addition, the role of different AMF species in TM uptake or sequestration was investigated.;In the first experiment, AMF community structure was analyzed from non-contaminated and TM contaminated sites. We found the diversity of native AMF was lower in soils and plant roots harvested from TM polluted soils than from unpolluted soils. We also found that the community structure of AMF was modified by TM contamination. Some AMF ribotypes were more often associated with TM contaminated sites, other ribotypes with uncontaminated sites, while still other ribotypes were found both in polluted and unpolluted soils.;In the second experiment, the effect of different organic and mineral N fertilization on AMF community structure was investigated. Variation in root-colonizing AMF community structure was observed in both organic and mineral fertilization. Some AMF ribotypes were more affiliated to organic fertilization and other to mineral fertilization. In addition, mineral fertilization reduced AMF ribotypes number while organic fertilization increased AMF ribotypes number. In this experiment, it was demonstrated that change in root-colonizing AMF community structure had a significant effect on plant productivity.;In the third experiment, the role of different AMF species ( G. irregulare and G. mosseae) in TM uptake by sunflower plants grown in soil amended with three different Cd levels was evaluated. It was demonstrated that AMF species differentially affected TM uptake or sequestration by sunflower plants. This experiment supported a different effect of AMF in TM uptake based on Cd concentration in soil and the AMF species involved.;Our research demonstrated that TM and N fertilization affected and shifted AMF community structure within roots and soils. It was shown that change in root-colonizing AMF community structure significantly affected plant productivity. In this study, it was showed that the AMF species G. irregulare was recorded in all uncontaminated sites while G. mosseae was the most abundant AMF species in TM contaminated sites. Therefore, the role of G. irregulare and G. mosseae in Cd uptake by sunflower plants grown in soils amended with three different Cd levels was investigated. The results indicated that AMF species mediate different mechanisms to alleviate TM toxicity in host plants, depending on AMF species and soil Cd level involved. We hypothesize that G. irregulare is a potentially important species for Cd phytoextration processes, while G. mosseae might be a suitable candidate for Cd and Zn phytostabilization processes.;Keywords: Arbuscular Mycorrhizal Fungi (AMF), biodiversity, trace metals, N fertilization, polluted soils, phytoremediation, PCR plus Denaturing gradient gel electrophoresis (DGGE), cloning and sequencing.
机译：通过大量使用矿物肥料和农用化学品，以及产生有毒废物的工业和其他活动，痕量金属（TM）不断在世界范围内添加到土壤中。由于TM不可生物降解，因此存在与金属污染的土壤相关的问题。积累在土壤中的TM影响土壤微生物的生物多样性。氮肥是提高土壤肥力和作物产量的广泛实践。但是，长期使用氮肥会对环境造成许多不利影响。氮肥的大量使用增加了土壤中TM的投入，在极端情况下，氮肥导致周围土壤和水的TM污染，并增加了植物组织中TM的浓度。此外，长期施用氮肥会改变和降低上层和地下生态系统的生物多样性。在TM污染和长期施用氮肥的土壤中调查了丛枝菌根真菌（AMF）的群落结构。此外，还研究了不同AMF种类在TM吸收或螯合中的作用。在第一个实验中，从非污染和TM污染的地点分析了AMF群落结构。我们发现，从TM污染的土壤中收获的土壤和植物根系中天然AMF的多样性要低于未污染的土壤。我们还发现AMF的群落结构被TM污染所修饰。一些AMF核糖型更常与TM污染位点相关，其他核糖型未受污染的位点，而在污染和未污染的土壤中仍发现其他核糖型。被调查了。在有机和矿物施肥中均观察到了根定殖的AMF群落结构的变化。一些AMF核型与有机肥和其他矿物肥有关。此外，矿物肥料减少了AMF核型数，而有机肥料增加了AMF核型数。在该实验中，证明了定根的AMF群落结构的变化对植物生产力具有显着影响。在第三个实验中，不同AMF种类（G.normale和G. mosseae）在向日葵吸收TM中的作用评价了在土壤中添加了三种不同镉水平的植物。事实证明，AMF物种差异地影响向日葵植物对TM的吸收或螯合。本实验基于土壤中Cd浓度和所涉及的AMF种类，支持了AMF对TM吸收的不同影响。结果表明，定根的AMF群落结构的变化显着影响了植物的生产力。在这项研究中，表明在所有未受污染的地点都记录了AMF物种不规则链霉菌，而mosseae是在TM污染的地点中最丰富的AMF物种。因此，研究了在三种不同镉水平下改良的土壤中生长的向日葵植物对不规则芽孢杆菌和mosseae菌吸收镉的作用。结果表明，AMF物种介导减轻宿主植物TM毒性的不同机制，具体取决于所涉及的AMF物种和土壤Cd水平。我们假设不规则芽孢杆菌是Cd植物灭绝过程的潜在重要物种，而mosseae可能是Cd和Zn植物稳定过程的合适候选者。污染的土壤，植物修复，PCR加上变性梯度凝胶电泳（DGGE），克隆和测序。

著录项

  • 作者

    Hassan, Saad El Din.;

  • 作者单位

    Universite de Montreal (Canada).;

  • 授予单位 Universite de Montreal (Canada).;
  • 学科 Biology Microbiology.;Agriculture Soil Science.
  • 学位 Ph.D.
  • 年度 2011
  • 页码 179 p.
  • 总页数 179
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 肿瘤学;
  • 关键词

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