Metal-Microbe Interactions in Freshwater Sediments

9807697 Gaillard该项目的总体目标是确定微生物过程对沉积物中金属化学形态的影响，即，评估细菌防御机制如何对金属胁迫作出反应，影响沉积物中金属的化学性质。 该项目将分两个阶段进行。第一阶段将包括调查受污染淡水沉积物的化学和微生物学。沿着污染梯度，将使用分子工具对三个地点的微生物生态学及其完整的地球化学特征进行研究。第二阶段将包括在实验室实验中，自然沉积微生物种群将提交锌应力。孔隙沃茨和微生物群落将作为暴露时间的函数进行监测，以确定金属应力是否导致群落变化以及与金属络合的特定配体的释放。同时，将使用X射线吸收精细结构探测沉积物颗粒中金属的局部分子环境的变化。 这项研究的预期结果是更好地了解控制污染沉积物中金属的物理和化学形式的过程。此外，还应提供新的证据，说明微生物在水生环境中金属的生物地球化学循环中所起的关键作用。

9807697Gaillard The overall objective of this project is to determine the influence of microbial processes on the chemical speciation of metals in sediments, i.e., to evaluate how bacterial defense mechanisms, in response to a metal stress, affect the chemistry of metals in sediments. The project will be conducted in two phases. The first phase will consist in investigating the chemistry and microbiology of contaminated freshwater sediments. Along a contamination gradient, the microbial ecology of three sites, as well as their complete geochemical characterization, will be performed using molecular tools. The second phase will consist in laboratory experiments where natural sedimentary microbial populations will be submitted to Zn stress. The pore waters and the microbial communities will be monitored as a function of exposure time to determine if metal stress results in community changes and the liberation of specific ligands that complex the metal. Concurrently, the changes in the local molecular environment of the metal, in the sediment particles, will be probed using X-Ray Absorption Fine Structure. The expected result of this research is a better understanding of the processes that are controlling the physical and chemical form of metals in contaminated sediments. In addition, it should pro-vide new evidence on the key role played by microorganisms in the biogeochemical cycles of metals in aquatic environments.