Hyporheic Microbial Response to Variations in Supply of Dissolved Organic Carbon

摘要98-06466芬德利高碳微生物对溶解有机碳供应变化的响应是导致水生态系统中有机物质许多重要转化的原因，它们的活性在不同生态系统和生态系统内不同生境之间差异很大。该项目将研究水系沉积物中溶解有机碳(DOC)细菌消耗的差异是否伴随着细菌物种相对丰度的变化。在一些溪流中，随着水沿着地下流动路径流动，DOC大幅下降，这些下降伴随着细菌丰度、生长和获取碳的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沿流路径的相似程度。我们的实验将使用已知地下DOC模式不同的溪流中的水。这一可变性范围将随着添加特定类别的化合物(例如腐植酸)而扩大，预计将导致微生物活动的巨大差异。我们可以获得微生物功能中定义明确的梯度，这使得我们能够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.