Biogeochemistry of Anaerobic Sedimentary Environments: An Integrated Geochemical and Microbiological Study of Dissimilatory Iron and Sulfate Reduction

9708535货车Cappellen提出了一种结合地球化学和微生物的方法来研究异化铁（III）和硫酸盐还原的动力学控制，这是厌氧环境中的两种主要呼吸途径。 实验将使用在格鲁吉亚萨佩洛岛盐沼中收集的沉积物进行，其中硫酸盐和铁还原菌是微生物种群的主要组成部分。 合作研究人员将使用16 S rRNA靶向寡核苷酸探针检测硫酸盐和Fe（III）还原细菌，结合活性测定，系统发育筛选和动力学流通反应器实验。 这些分子探针将确定沉积物芯层中硫酸盐和铁还原菌的相对丰度，并提供独立信息以区分化学途径和微生物途径。 在沉积物岩心的未受干扰的部分上的流通实验将提供所需的动力学数据，以推导出两种异化途径的速率表达式，作为温度、基质可用性（有机物、铁（三）羟基氧化物、硫酸盐）和孔隙溶液的组成（硫化物、营养物、pH值）的函数。 遗传学信息基因序列的分析将评估在反应器系统上繁殖的铁和硫酸盐还原菌与自然发生的种群之间的相似性。 该提案是应NSF 96-152环境地球化学和生物地球化学（EGB）征集而提交的。 拟议的研究得到地球科学司和海洋科学司的联合支持。

9708535 Van Cappellen A combined geochemical and microbiological approach is proposed to investigate the kinetic controls of dissimilatory iron (III) and sulfate reduction, two of the major respiratory pathways in anaerobic environments. Experiments will be performed using sediments collected in the saltmarsh of Sapelo Island, Georgia, where sulfate and iron reducing bacteria are major components of the microbial population. The co-investigators will use 16S rRNA-targeted oligonucleotide probes to detect sulfate- and Fe(III)-reducing bacteria, in conjunction with activity assays, phylogenetic screening, and kinetic flow-through reactor experiments. The molecular probes will establish the relative abundances of sulfate and iron reducing bacteria in the sediments core sections, and provide independent information to differentiate chemical and microbial pathways. The flow-through experiments on undisturbed sections of sediment cores will provide the kinetic data needed to derive rate expressions for the two dissimilatory pathways, as a function of temperature, substrate availability (organic matter, iron(III) oxyhydroxides, sulfate) and the composition of the pore solution (sulfide, nutrients, pH). The analysis of phylogenetically informative gene sequences will assess the similarity between the iron and sulfate reducing bacteria that propagate on the reactor systems and the naturally-occurring populations. This proposal was submitted in response to the Environmental Geochemistry and Biogeochemistry (EGB) solicitation, NSF 96-152. The proposed research is being jointly supported by the Divisions of Earth Sciences and Ocean Sciences.