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Influence of Nitrate on Microbial Reduction of Pertechnetate

机译：硝酸盐对高tech酸盐微生物还原的影响

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Factors influencing microbial reduction of Tc(Ⅶ) in nitrate and radionuclide contaminated aquifer sediments were investigated using sediment microcosms containing organic electron donor, nitrate and Tc(Ⅶ). Microcosms underwent nitrate reduction followed by Tc(Ⅶ) reduction. During this transition, the microbial community changed from being dominated by bacteria affiliated with the genus Paenibacillus during the nitrate reduction phase, to those affiliated with genera Agrobacterium, Geothrix, and Desulfosporosinus during the Tc(Ⅶ) reduction phase. To investigate the mechanism of Tc(Ⅶ) reduction, the nitrate reducing strains Agrobacterium FRC-A2, Azoarcus FRC-B1, and a fermentative Clostridium FRC-C11 were isolated from sediment microcosms undergoing Tc(Ⅶ) reduction. Nitrate reducing bacteria reduced Tc(Ⅶ) effectively only in the presence of Fe(Ⅲ) and after nitrate was reduced, implying a major role for Fe(Ⅱ) as an electron shuttle in Tc(Ⅶ) reduction. It is likely that accumulation of nitrite blocks Fe(Ⅱ) production and hence Tc(Ⅶ) reduction during the active nitrate reduction phase. The pure culture of Clostridium FRC-C11 is able to reduce Tc(Ⅶ) enzymatically with H2 or glucose as electron donor and deposits insoluble Tc compounds within the cells in a manner that is not significantly influenced by the presence of nitrate. These results provided a possible mechanism for Tc(Ⅶ) reduction independent of Fe(Ⅲ) and not influenced by nitrate.
机译：利用含有有机电子给体，硝酸盐和Tc（Ⅶ）的沉积物微观世界，研究了硝酸盐和放射性核素污染的含水层沉积物中Tc（Ⅶ）微生物减少的影响因素。缩微进行了硝酸盐还原，然后是Tc（Ⅶ）还原。在此过渡过程中，微生物群落从在硝酸盐还原阶段中与杆状芽孢杆菌属相关的细菌占主导地位转变为在Tc（reduction）还原阶段中与农杆菌属，Geothrix和Desulfosporosinus属相关的细菌。为了研究Tc（Ⅶ）还原的机理，从经历Tc（Ⅶ）还原的沉积物微观世界中分离了硝酸盐还原菌株农杆菌FRC-A2，固氮弧菌FRC-B1和发酵梭菌FRC-C11。硝酸盐还原菌仅在Fe（Ⅲ）存在下和硝酸盐还原后才有效还原Tc（Ⅶ），这暗示着Fe（Ⅱ）作为电子穿梭在Tc（shuttle）还原中起主要作用。亚硝酸盐的积累可能会阻止硝酸盐还原过程中Fe（Ⅱ）的产生，从而阻止Tc（Ⅶ）的还原。梭状芽孢杆菌FRC-C11的纯培养物能够以H 2或葡萄糖作为电子供体以酶的方式降低Tc（I），并以不受硝酸盐存在的显着影响的方式在细胞内沉积不溶性Tc化合物。这些结果为Tc（Fe）的还原提供了一种可能的机制，而与Fe（Ⅲ）无关，不受硝酸盐的影响。

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  • 来源
    《Environmental Science & Technology》 |2008年第6期|1910-1915|共页
  • 作者

    XIANGZHEN LI; LEE R. KRUMHOLZ;

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  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
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