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首页> 外文期刊>Environmental Science & Technology >Coupled Mercury-Cell Sorption, Reduction, and Oxidation on Methylmercury Production by Geobacter sulfurreducens PCA
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Coupled Mercury-Cell Sorption, Reduction, and Oxidation on Methylmercury Production by Geobacter sulfurreducens PCA

机译：土工硫还原剂PCA对汞-细胞的吸附，还原和氧化耦合，对甲基汞的生产

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G. sulfurreducens PCA cells have been shown to reduce, sorb, and methylate Hg(Ⅱ) species, but it is unclear whether this organism can oxidize and methylate dissolved elemental Hg(0) as shown for Desulfovibrio desulfuricans ND132. Using Hg(Ⅱ) and Hg(0) separately as Hg sources in washed cell assays in phosphate buffered saline (pH 7.4), we report how cell-mediated Hg reduction and oxidation compete or synergize with sorption, thus affecting the production of toxic methylmercury by PCA cells. Methyiation is found to be positively correlated to Hg sorption (r = 0.73) but negatively correlated to Hg reduction (r = -0.62). These reactions depend on the Hg and cell concentrations or the ratio of Hg to cellular thiols (-SH). Oxidation and methyiation of Hg(0) are favored at relatively low Hg to cell-SH molar ratios (e.g., ＜1). Increasing Hg to cell ratios from 0.25 × 10~(-19) to 2.5 × 10~(-19) moles-Hg/cell (equivalent to Hg/cell-SH of 0.71 to 71) shifts the major reaction from oxidation to reduction. In the absence of five outer membrane c-type cytochromes, mutant ΔomcBESTZ also shows decreases in Hg reduction and increases in methyiation. However, the presence of competing thiol-binding ions such as Zn~(2+) leads to increased Hg reduction and decreased methyiation. These results suggest that the coupled cell-Hg sorption and redox transformations are important in controlling the rates of Hg uptake and methyiation by G. sulfurreducens PCA in anoxic environments.
机译：G. sulfreducens PCA细胞已显示出还原，吸附和甲基化Hg（Ⅱ）种类，但尚不清楚该生物是否能氧化和甲基化溶解的Hg（0）元素，如Desulfovibrio desulfuricans ND132所示。在磷酸盐缓冲液（pH 7.4）中进行洗涤细胞测定时，分别使用Hg（Ⅱ）和Hg（0）作为Hg来源，我们报告了细胞介导的Hg还原和氧化如何与吸附竞争或协同作用，从而影响有毒甲基汞的产生通过PCA细胞。发现甲基化与汞吸附呈正相关（r = 0.73），但与汞还原呈负相关（r = -0.62）。这些反应取决于Hg和细胞浓度或Hg与细胞硫醇（-SH）的比例。 Hg（0）相对于H-cell-SH摩尔比相对较低（例如＜1）时，Hg（0）的氧化和甲基化作用更为有利。 Hg与电池的比例从0.25×10〜（-19）摩尔Hg / cell增加到2.5×10〜（-19）摩尔Hg / cell（相当于Hg / cell-SH为0.71至71）使主要反应从氧化转变为还原。在不存在五种外膜c型细胞色素的情况下，突变体ΔomcBESTZ还显示出汞减少的减少和甲酰化的增加。但是，竞争性硫醇结合离子（例如Zn〜（2+））的存在会导致汞还原量增加和甲酰化降低。这些结果表明，在缺氧环境中，耦合的细胞-Hg吸附和氧化还原转化对于控制G.硫还原菌PCA的Hg吸收和甲基化速率很重要。

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  • 来源
    《Environmental Science & Technology》 |2014年第20期|11969-11976|共8页
  • 作者

    Hui Lin; Jennifer L. Morrell-Falvey; Balaji Rao; Liyuan Liang; Baohua Gu;

  • 作者单位

    Environmental Sciences Division Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States;

    Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States;

    Environmental Sciences Division Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States;

    Environmental Sciences Division Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States;

    Environmental Sciences Division Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States;

  • 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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