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Characteristics and electron donor requirements of perchlorate degradation by mixed and pure-culture bacteria.

机译：混合细菌和纯培养细菌降解高氯酸盐的特性和电子供体要求。

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摘要

Perchlorate contamination of the environment has received increasing recognition since the late 1990s. Despite being a very thermodynamically favorable electron acceptor, perchlorate remains recalcitrant in many soils and waters contaminated with this compound. The most effective method for treating perchlorate-contaminated sites appears to be anaerobic bioremediation where perchlorate is used as an electron acceptor for microbial growth. Several mixed- and pure-culture bacteria were used to assess various aspects of perchlorate reduction.; Seven novel perchlorate-degrading bacteria were isolated from microcosms developed from material collected at a perchlorate-contaminated site, the Longhorn Army Ammunition Plant, outside Karnack, Texas. Two of these isolates were capable of growth on hydrogen, perchlorate, and inorganic carbon. Five additional novel heterotrophic bacteria were also isolated from these microcosms. A comparison of 16S rDNA sequences recovered from these seven isolates showed that they are distributed within the beta and epsilon subclasses of Proteobacteria. The two isolates capable of autotrophic perchlorate degradation appear to be within the genus Dechloromonas.; Zero-valent iron (Fe(0)) should be a very favorable electron donor for abiotic and biotic perchlorate degradation. While abiotic reduction did not occur, enhanced microbial perchlorate reduction was observed in microcosms containing Fe(0). This activity was limited, however, by two inhibitory effects. Degradation ceased above pH 8.7, a pH range encountered during Fe(0) corrosion. In addition, Fe(0) indirectly inhibited perchlorate reduction over time by release of Fe(II), which likely affected bacteria by adsorption of Fe(II) on bacterial surfaces or by deposition of precipitates such as vivianite or siderite on bacterial surfaces.; A highly enriched mixed culture was used to assess the role of electron donor addition and redox potential on perchlorate degradation. Lactate, acetate, hydrogen, and poplar tree root products supported perchlorate reduction. Under conditions tested, the optimal electron donor requirements were approximately 1.2 mg COD per mg perchlorate. Perchlorate degradation was observed to decrease in microcosms where redox potential was increased. However, significant perchlorate reduction occurred at redox potentials as high as +180 mV (versus a standard hydrogen electrode). Rate coefficients were determined for this enrichment culture.
机译：自1990年代后期以来，高氯酸盐对环境的污染日益受到重视。尽管高氯酸盐是热力学上非常有利的电子受体，但在许多被该化合物污染的土壤和水中，高氯酸盐仍然是难降解的。处理高氯酸盐污染部位最有效的方法似乎是厌氧生物修复，其中高氯酸盐被用作微生物生长的电子受体。几种混合培养细菌和纯培养细菌被用于评估高氯酸盐还原的各个方面。从在高氯酸盐污染地点（得克萨斯州卡纳克市外的Longhorn Army弹药厂）收集的材料中产生的微观世界中分离出了七个降解高氯酸盐的细菌。这些分离物中的两个能够在氢气，高氯酸盐和无机碳上生长。从这些微观世界中还分离出了另外五种新型异养细菌。从这七个分离物中回收的16S rDNA序列的比较表明，它们分布在变形杆菌的beta和epsilon亚类中。能够自养高氯酸盐降解的两种分离株似乎在 Dechloromonas 属中。零价铁（Fe（0））应该是非生物和生物高氯酸盐降解的非常有利的电子供体。虽然未发生非生物减少，但在含有Fe（0）的微观世界中观察到了微生物高氯酸盐减少的增强。但是，该活性受到两个抑制作用的限制。在pH 8.7（Fe（0）腐蚀期间遇到的pH范围）以上停止降解。另外，Fe（0）通过释放Fe（II）间接抑制高氯酸盐随时间的减少，Fe（II）可能通过在细菌表面吸附Fe（II）或在细菌表面沉积沉淀物（如堇青石或菱铁矿）来影响细菌。使用高度浓缩的混合培养物评估电子供体的添加和氧化还原电势对高氯酸盐降解的作用。乳酸，乙酸盐，氢和杨树根产品支持减少高氯酸盐。在测试条件下，最佳电子给体需求为每毫克高氯酸盐约1.2毫克化学需氧量。在氧化还原电位增加的微观世界中观察到高氯酸盐的降解减少。但是，在高达+180 mV的氧化还原电势下（相对于标准氢电极），高氯酸盐的还原率显着降低。确定该富集培养的速率系数。

著录项

  • 作者

    Shrout, Joshua Duncan.;

  • 作者单位

    The University of Iowa.;

  • 授予单位 The University of Iowa.;
  • 学科 Engineering Environmental.
  • 学位 Ph.D.
  • 年度 2002
  • 页码 163 p.
  • 总页数 163
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 环境污染及其防治;
  • 关键词

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