Microbial Community Structure and Arsenic Biogeochemistry in Two Arsenic-Impacted Aquifers in Bangladesh.
Microbial Community Structure and Arsenic Biogeochemistry in Two Arsenic-Impacted Aquifers in Bangladesh.
复制标题
DOI：
10.1128/mbio.01326-17
复制
发表时间：
2017-11-28
期刊：
影响因子：
6.4
通讯作者：
Mailloux BJ
中科院分区：
文献类型：
--
作者：
Gnanaprakasam ET;Lloyd JR;Boothman C;Ahmed KM;Choudhury I;Bostick BC;van Geen A;Mailloux BJ
长期暴露于用于饮用和灌溉的浅层地下水中的微量砷（As）使数百万人面临慢性疾病的风险。虽然微生物的过程涉及动员砷从含水层沉积物进入地下水，精确的机制仍然不明确。这项工作的目标是，第一次，一套全面的国家的最先进的分子技术，以更好地限制土著微生物群落和铁和砷矿物相存在于沉积物中的两个特征良好的砷影响的含水层在孟加拉国之间的关系。在这两个网站，砷酸盐[As（V）]是目前在沉积物中的深度与低水As浓度的主要物种，而大多数沉积物As是亚砷酸盐[As（III）]在深度与水As浓度升高。这与微生物As（V）还原在动员砷中的作用是一致的。16S rRNA基因分析表明，富含砷的沉积物中的异化Fe（III）和As（V）的减少，而相关性分析涉及的系统发育组通常不与作为动员不同的细菌群落的殖民。研究结果表明，直接作为氧化还原转换是中央砷的命运和运输，并有一个残留的反应池的As（V）和Fe（III）在更深的沉积物，可以释放微生物呼吸响应水文扰动，如增加地下水抽水，引入活性有机碳的深度。从管井威尔斯收集的沃茨中的砷的消耗威胁着全世界数百万人的生命，在南亚的洪泛平原和三角洲地区尤为严重。砷从这些含水层内的天然沉积物迁移到地下水的原因很复杂，最近的研究表明，沉积物中的微生物可能是原因。在深度缺氧的情况下，专业细菌被认为能够利用沉积物中的金属来支持它们的新陈代谢。通过这些过程，砷污染的铁矿物发生转化，导致砷释放到含水层沃茨中。以孟加拉国的一个实地为重点，利用最先进的地质和微生物学技术进行了一项全面的多学科研究，有助于更好地了解高砷含水层中天然存在的微生物，以及它们如何将沉积物的化学性质转化为潜在的致命影响。
Long-term exposure to trace levels of arsenic (As) in shallow groundwater used for drinking and irrigation puts millions of people at risk of chronic disease. Although microbial processes are implicated in mobilizing arsenic from aquifer sediments into groundwater, the precise mechanism remains ambiguous. The goal of this work was to target, for the first time, a comprehensive suite of state-of-the-art molecular techniques in order to better constrain the relationship between indigenous microbial communities and the iron and arsenic mineral phases present in sediments at two well-characterized arsenic-impacted aquifers in Bangladesh. At both sites, arsenate [As(V)] was the major species of As present in sediments at depths with low aqueous As concentrations, while most sediment As was arsenite [As(III)] at depths with elevated aqueous As concentrations. This is consistent with a role for the microbial As(V) reduction in mobilizing arsenic. 16S rRNA gene analysis indicates that the arsenic-rich sediments were colonized by diverse bacterial communities implicated in both dissimilatory Fe(III) and As(V) reduction, while the correlation analyses involved phylogenetic groups not normally associated with As mobilization. Findings suggest that direct As redox transformations are central to arsenic fate and transport and that there is a residual reactive pool of both As(V) and Fe(III) in deeper sediments that could be released by microbial respiration in response to hydrologic perturbation, such as increased groundwater pumping that introduces reactive organic carbon to depth. The consumption of arsenic in waters collected from tube wells threatens the lives of millions worldwide and is particularly acute in the floodplains and deltas of southern Asia. The cause of arsenic mobilization from natural sediments within these aquifers to groundwater is complex, with recent studies suggesting that sediment-dwelling microorganisms may be the cause. In the absence of oxygen at depth, specialist bacteria are thought able to use metals within the sediments to support their metabolism. Via these processes, arsenic-contaminated iron minerals are transformed, resulting in the release of arsenic into the aquifer waters. Focusing on a field site in Bangladesh, a comprehensive, multidisciplinary study using state-of-the-art geological and microbiological techniques has helped better understand the microbes that are present naturally in a high-arsenic aquifer and how they may transform the chemistry of the sediment to potentially lethal effect.