Isolation of an arsenate-respiring bacterium from a redox front in an arsenic-polluted aquifer in West Bengal, Bengal Basin.
Isolation of an arsenate-respiring bacterium from a redox front in an arsenic-polluted aquifer in West Bengal, Bengal Basin.
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DOI：
10.1021/es504707x
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发表时间：
2015-03
影响因子：
11.4
通讯作者：
T. H. Osborne;J. McArthur;P. K. Sikdar;J. Santini
中科院分区：
文献类型：
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作者：
T. H. Osborne;J. McArthur;P. K. Sikdar;J. Santini
砷对地下水的自然污染对全世界数千万人的健康产生了不利影响，东南亚三角洲的含水层尤其受到污染。污染主要是由沉积的Fe（III）-羟基氧化物的微生物还原引起的，或作为其副反应，但负责As释放的生物体尚未被分离。在这里，我们报告的第一个隔离的异化砷酸盐还原剂的沉积物中的孟加拉盆地在西孟加拉。细菌，这里指定为WB 3，呼吸可溶性砷酸盐，并将其还原与乙酸盐的氧化偶联;因此，WB 3与地下水的砷污染过程有关，这主要是由亚砷酸盐引起的。细菌WB 3还能够使用乙酸盐作为电子供体还原溶解的柠檬酸铁（III）、固体羟基氧化铁（III）和元素硫。它是脱硫单胞菌属的成员，并具有异化砷酸盐还原酶，使用简并聚合酶链反应引物鉴定。从WB 3被隔离的沉积物是棕色的，更新世砂在地面以下35.2米的深度（mbgl）。这一水平低于棕色砂层和上覆的还原灰色全新世含水层砂层之间的边界约3 cm。颜色边界被解释为一个还原锋，释放砷的再吸收下行，产生一个高负荷的不稳定的砷吸附到沉积物的深度为35.8 mbgl和地下水中的砷浓度达到>1000 μg/L。
Natural pollution of groundwater by arsenic adversely affects the health of tens of millions of people worldwide, with the deltaic aquifers of SE Asia being particularly polluted. The pollution is caused primarily by, or as a side reaction of, the microbial reduction of sedimentary Fe(III)-oxyhydroxides, but the organism(s) responsible for As release have not been isolated. Here we report the first isolation of a dissimilatory arsenate reducer from sediments of the Bengal Basin in West Bengal. The bacterium, here designated WB3, respires soluble arsenate and couples its reduction to the oxidation of acetate; WB3 is therefore implicated in the process of arsenic pollution of groundwater, which is largely by arsenite. The bacterium WB3 is also capable of reducing dissolved Fe(III) citrate, solid Fe(III)-oxyhydroxide, and elemental sulfur, using acetate as the electron donor. It is a member of the Desulfuromonas genus and possesses a dissimilatory arsenate reductase that was identified using degenerate polymerase chain reaction primers. The sediment from which WB3 was isolated was brown, Pleistocene sand at a depth of 35.2 m below ground level (mbgl). This level was some 3 cm below the boundary between the brown sands and overlying reduced, gray, Holocene aquifer sands. The color boundary is interpreted to be a reduction front that releases As for resorption downflow, yielding a high load of labile As sorbed to the sediment at a depth of 35.8 mbgl and concentrations of As in groundwater that reach >1000 μg/L.