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首页> 外文学位 >The Microbial Ecology and Biogeochemistry of Cyanobacteria in the Arsenic-rich and Inorganic Carbon-limited Geothermal Waters of El Tatio Geyser Field, Chile.
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The Microbial Ecology and Biogeochemistry of Cyanobacteria in the Arsenic-rich and Inorganic Carbon-limited Geothermal Waters of El Tatio Geyser Field, Chile.

机译：智利El Tatio间歇泉油田富含砷和无机碳限制的地热水中蓝藻的微生物生态和生物地球化学。

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摘要

Geothermal settings are some of the best-known analogs for early earth environments and among the best places to investigate the impact of extreme conditions on microbial life. El Tatio Geyser Field (ETGF) is a geothermal setting located at 4,300m in the Atacama Desert region of Chile. Its high-elevation desert position leads to high UV-flux, rapid evaporation, and mineral precipitation. El Tatio geothermal waters also possess extremely limited concentrations of life-essential nutrients, such as dissolved inorganic carbon (DIC as CO 2(aq) + HCO3-), contain among the highest naturally occurring concentrations of the toxic element arsenic (As as H 3AsO3 0 + HXAsO4 3-X), and are buffered to circumneutral pH by arsenate (H2AsO 4 -/HAsO4 2-; pKa ~ 6.9 at 25°C).;Cyanobacteria were found to be the most important primary producers supporting microbial communities in El Tatio geothermal waters. The objective of this dissertation work was to characterize the role of cyanobacteria in the ETGF microbial ecosystem, and determine the response of cyanobacteria to the high-As and low-DIC conditions present at ETGF. Field observations, geochemical analyses, and next-generation 16S rRNA gene sequencing approaches were used to determine the geochemical controls on cyanobacterial distribution, the phylogenetic diversity of El Tatio cyanobacteria, and the corresponding microbial community structure at sites with and without cyanobacteria. Four cultured cyanobacterial strains were isolated from ETGF mat material, and experiments were performed to assess the growth and carbon-uptake response of these strains to low DIC, AsIII, and AsV.;AsIII and temperature negatively controlled the abundance and distribution of cyanobacteria in geothermal outflows throughout ETGF, whereas AsV positively influenced these factors. In the laboratory, AsIII inhibited the growth of cultured strains, while As V stimulated growth. Closed-system experiments showed significantly increased carbon uptake and growth in the presence of AsV, due to the ability of arsenate to offset the rapid upward pH shift that often occurs in mats during photosynthesis, thereby maintaining DIC in the preferred forms for cyanobacterial uptake. These results showed that AsV plays a positive role in the ETGF microbial ecosystem by increasing the productivity of cyanobacterial mats under low DIC and arsenate-buffered conditions.
机译：地热环境是早期地球环境中一些最著名的类似物，也是研究极端条件对微生物生命影响的最佳场所之一。 El Tatio间歇泉油田（ETGF）是位于智利阿塔卡马沙漠地区4,300m处的地热环境。其高海拔的沙漠位置导致高紫外线通量，快速蒸发和矿物沉淀。 El Tatio地热水还具有极其有限的生命必需养分浓度，例如溶解的无机碳（DIC为CO 2（aq）+ HCO3-），其中自然含有最高浓度的有毒元素砷（如H 3AsO3 0 + HXAsO4 3-X），并被砷酸盐（H2AsO 4-/ HAsO4 2-; pKa〜6.9在25°C）缓冲至周围pH。发现蓝细菌是支持El微生物群落最重要的主要生产者Tatio地热水。这项工作的目的是表征蓝细菌在ETGF微生物生态系统中的作用，并确定蓝细菌对ETGF存在的高As和低DIC条件的响应。现场观察，地球化学分析和下一代16S rRNA基因测序方法用于确定对蓝细菌分布，El Tatio蓝细菌的系统发育多样性以及在有和没有蓝细菌的场所的相应微生物群落结构的地球化学控制。从ETGF垫材料中分离出4个培养的蓝细菌菌株，并进行了实验以评估这些菌株对低DIC，AsIII和AsV的生长和碳吸收响应; AsIII和温度对地热中蓝细菌的丰度和分布有负面影响整个ETGF流出，而AsV积极影响这些因素。在实验室中，AsIII抑制了培养菌株的生长，而As V刺激了生长。封闭系统实验表明，在砷化氢存在下，碳的吸收和生长显着增加，这是由于砷酸盐具有抵消光合作用过程中席子中经常发生的pH值快速上升的能力，从而使DIC保持为蓝藻吸收的优选形式。这些结果表明，在低DIC和砷酸盐缓冲条件下，AsV通过提高蓝藻垫的生产力在ETGF微生物生态系统中发挥积极作用。

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  • 作者

    Myers, Kimberly Dawn.;

  • 作者单位

    The University of Texas at Austin.;

  • 授予单位 The University of Texas at Austin.;
  • 学科 Geobiology.;Geochemistry.;Microbiology.
  • 学位 Ph.D.
  • 年度 2015
  • 页码 253 p.
  • 总页数 253
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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