Enhancement of biological reduction of hematite by electron shuttling and Fe(II) complexation.
Enhancement of biological reduction of hematite by electron shuttling and Fe(II) complexation.
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DOI：
10.1021/es011139s
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发表时间：
2002-05
影响因子：
11.4
通讯作者：
R. Royer;W. D. Burgos;Angela S Fisher;R. F. Unz;B. Dempsey
中科院分区：
文献类型：
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作者：
R. Royer;W. D. Burgos;Angela S Fisher;R. F. Unz;B. Dempsey
研究了自然有机物质（NOM）对腐臭谢瓦氏菌（Shewanella putrefaciens） CN32对赤铁矿（α - fe2o3）生物还原的促进作用。氢是电子供体。在为期5天的实验中，蒽醌-2,6-二磺酸盐（AQDS）、甲基紫素和亚甲基蓝[Ew0 （pH 7）为0.011 V或更低的醌]、亚铁锌[一种强Fe（II）络合剂]和表征的水生NOM （Georgetown NOM或Suwannee River fulvic acid）增强了生物还原，而1,4-苯醌（Ew0值= 0.280 V）则没有。除亚甲基蓝外，总铁（II）产量与亚铁锌或NOM浓度呈线性关系，而与醌类浓度无线性关系。铁（II）和亚甲基蓝浓度之间的这种线性关系可能是由于系统相对于亚甲基蓝远远不饱和或热力学驱动力的损失。在一定浓度的AQDS和不同浓度的铁锌条件下，总铁（II）产量与铁锌浓度呈线性关系。AQDS和亚铁锌的强化作用是叠加的。NOM既可以作为电子穿梭体，也可以作为Fe（II）络合剂；然而，与醌相比，NOM对赤铁矿还原的浓度依赖性更类似于亚铁锌。NOM可能首先通过电子穿梭增强赤铁矿还原，然后通过Fe（II）络合进一步增强赤铁矿还原，从而阻止Fe（II）吸附到赤铁矿和细胞表面。
Natural organic matter (NOM) enhancement of the biological reduction of hematite (alpha-Fe2O3) by the dissimilatory iron-reducing bacterium Shewanella putrefaciens strain CN32 was investigated under nongrowth conditions designed to minimize precipitation of biogenic Fe(II). Hydrogen served as the electron donor. Anthraquinone-2,6-disulfonate (AQDS), methyl viologen, and methylene blue [quinones with an Ew0 (pH 7) of 0.011 V or less], ferrozine [a strong Fe(II) complexing agent], and characterized aquatic NOM (Georgetown NOM or Suwannee River fulvic acid) enhanced bioreduction in 5-day experiments whereas 1,4-benzoquinone (Ew0 value = 0.280 V) did not. A linear relationship existed between total Fe(II) produced and concentrations of ferrozine or NOM but not quinones, except in the case of methylene blue. Such a linear relationship between Fe(II) and methylene blue concentrations could be due to the systems being far undersaturated with respect to methylene blue or the loss of the thermodynamic driving force. A constant concentration of AQDS and variable concentrations of ferrozine produced a linear relationship between total Fe(II) produced and the concentration of ferrozine. Enhancement effects of both AQDS and ferrozine were additive. NOM may serve as both an electron shuttle and an Fe(II) complexant; however, the concentration dependence of hematite reduction with NOM was more similar to ferrozine than quinones. NOM likely enhances hematite reduction initially by electron shuttling and then further by Fe(II) complexation, which prevents Fe(II) sorption to hematite and cell surfaces.