Hyporheic Microbial Response to Variations in Supply of Dissolved Organic Carbon

微生物参与了水生生态系统中许多重要的有机物质转化，其活动在不同的生态系统和生态系统内不同的生境之间差异很大。该项目将研究河流沉积物中溶解有机碳（DOC）细菌消耗的差异是否伴随着细菌种类相对丰度的变化。在一些河流中，当水沿着地下流动路径移动时，DOC会大幅下降，这些下降伴随着细菌丰度、生长和获取碳的细胞外酶分配的显著下降。我们将使用DNA-DNA杂交来揭示溪流之间和流动路径的相似性程度。我们的实验将使用已知地下DOC模式变化的溪流中的水。随着特定种类化合物（如腐植酸）的添加，这种变化范围将会扩大，预计会导致微生物活性的巨大差异。我们对微生物功能中定义良好的梯度的访问允许对微生物群落中功能和结构之间的潜在联系进行强有力的测试。

Abstract 98-06466 Findlay Hyporheic microbial response to variations in supply of dissolved organic carbon Microbes are responsible for many important transformations of organic materials in aquatic ecosystems and their activity varies dramatically among ecosystems and among habitats within ecosystems. This project will examine whether differences in bacterial consumption of dissolved organic carbon (DOC) in stream sediments are accompanied by shifts in the relative abundance of bacterial species. In some streams there are large declines in DOC as water moves along subsurface flowpaths and these declines are accompanied by significant drops in bacterial abundance, growth and shifts in allocation among carbon-acquiring extracellular enzymes. We will use DNA-DNA hybridization to reveal the degree of similarity among streams and along flowpaths. Our experiments will use water from streams known to vary in subsurface DOC patterns. This range in variability will be augmented with additions of specific classes of compounds (e.g. humic acids) expected to result in large differences in microbial activity. Our access to well-defined gradients in microbial function permits a powerful test of the potential link between function and structure in microbial communities.