Role of Thioarsenic Compounds in As(III) Oxidation in an Alkaline Lake

这项研究将以碱性、硫酸盐和富砷的莫诺湖底水为研究地点，试图阐明微生物组合分解硫代砷酸盐的途径。将进行浓缩培养和操作实验，以测试不同的电子受体对硫代砷酸盐分解的影响。PI将分析微生物群落，以确定哪些生物体和哪些酶系统对硫代砷酸盐的富集物做出反应，以帮助确定途径。这些实验旨在解决以下问题：1)以砷酸盐、硝酸盐或氧为电子受体的硫代砷酸盐的行为是什么？每对反应物都有特定的微生物群吗？2)反应的产物是什么？3)硫代砷酸盐分解过程中基因表达如何变化？硫代砷酸盐氧化的途径有哪些？这项研究的结果将是相关的，不仅对于更好地了解莫诺湖中的砷循环，而且对于在其他中性或碱性环境中建模砷，这些环境中存在亚砷酸盐和硫化物，并暴露在不断变化的氧化还原条件下。硫代砷酸盐的转化在碱性温泉、工业废弃场或基岩中含有含砷和含硫矿物的含水层中可能特别重要。一个结果将是更好地了解缺氧地下水中砷在波动的氧化还原条件下的转化和迁移性。这些信息也可能对设计生物修复策略有用。拟议的研究也与理解和模拟砷在地球生命演化早期阶段的作用有关。

This research will seek to elucidate the pathway for thioarsenate decomposition by microbial assemblages, using alkaline, sulfidic and arsenic-enriched Mono Lake bottom waters as a study site. Enrichment cultures and manipulation experiments will be performed to test the effects of different electron acceptors on thioarsenate decomposition. The PI will analyze the microbial communities to determine which organisms and which enzyme systems respond to enrichments with thioarsenates to aid in identifying pathways. These experiments are designed to address the following questions: 1) What is the behavior of thioarsenate with arsenate, nitrate or oxygen as electron acceptors? Are there specific groups of microbes associated with each pair of reactants? 2) What are the products of the reaction? 3) How does gene expression change during thioarsenate decomposition? What are the pathways involved in thioarsenate oxidation? The results of this study will be relevant, not only for a better understanding arsenic cycling in Mono Lake, but for modeling arsenic in other neutral or alkaline environments where arsenite and sulfide are present and exposed to changing redox conditions. Thioarsenate transformation may be of particular importance in alkaline hot springs, industrial waste sites, or aquifers with bedrock containing arsenic- and sulfur-bearing minerals. One outcome will be a better understanding of arsenic transformations and mobility under fluctuating redox conditions in anoxic groundwater. The information may also be useful in designing bioremediation strategies. The proposed studies are also relevant to understanding and modeling the role of arsenic in the early stages of the evolution of life on Earth.