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

9708535 Van Cappellen提出了一种地球化学和微生物学相结合的方法来研究厌氧环境中异化铁(III)和硫酸盐还原的动力学控制，这两个途径是主要的呼吸途径。实验将使用在佐治亚州萨佩洛岛盐沼收集的沉积物进行，那里的硫酸盐和铁还原细菌是微生物种群的主要组成部分。合作调查人员将使用16S rRNA靶向寡核苷酸探针来检测硫酸盐和铁(III)还原细菌，并结合活性分析、系统发育筛选和动力学流动反应器实验。分子探针将确定沉积物岩心剖面中硫酸盐和铁还原细菌的相对丰度，并为区分化学和微生物途径提供独立的信息。在沉积物岩心的未受干扰的剖面上进行的贯通实验将提供所需的动力学数据，以推导出作为温度、底物可用性(有机质、铁(III)氧氢氧化物、硫酸盐)和孔隙溶液组成(硫化物、营养物质、pH)的函数的两条异化路径的速率表达式。对系统发育信息基因序列的分析将评估在反应堆系统中繁殖的铁和硫酸盐还原细菌与自然发生的种群之间的相似性。本提案是应环境地球化学和生物地球化学(EGB)征集而提交的，NSF 96-152。这项拟议的研究由地球科学部和海洋科学部共同支持。

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.