Metal-Microbe Interactions in Freshwater Sediments

这个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，即评估细菌对金属胁迫的防御机制如何影响沉积物中金属的化学组成。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，将使用分子工具执行三个地点的微生物生态及其完整的地球化学特征。第二阶段将在实验室实验中进行，自然沉积微生物种群将受到锌胁迫。将监测孔隙水和微生物群落，作为暴露时间的函数，以确定金属应力是否导致群落变化和使金属络合的特定配体的释放。同时，将利用X射线吸收精细结构来探索金属在沉积物颗粒中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受污染沉积物中金属的物理和化学形态的过程。此外，它还应为微生物在水环境中金属的生物地球化学循环中发挥的关键作用提供新的证据。

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.