REU: Microbial Mediation of Arsenic Redox Cycling in Geothermally-Influenced Surface Waters

在加利福尼亚州欧文斯河谷受地热影响的地热峡谷地表水中，观察到砷(As)从III到V的快速微生物氧化。该项目将研究这一微生物过程的生化机制和生态方面。砷氧化菌株(S)将从从热溪获得的混合培养物中分离出来，该混合培养物目前保存在P.I.S实验室，并保留氧化AS(III)的能力。将开发用于混合培养的基因探针(基于16S-rRNA序列)，用于指导As(III)氧化菌纯培养(S)的分离，对纯菌株(S)进行遗传特征和系统发育分类，并确定As(III)氧化细菌在热溪峡谷野外的空间分布。对分离的As(III)-氧化菌(S)进行生化研究，以确定微生物As(III)氧化的动力学和机理。将进行实验室和实地研究相结合的研究，以确定这一过程是否与排毒或能量获取有关。如果资源允许，将对水生大型植物表面大量微生物定植的生态后果进行初步评估，这是以前的野外研究中观察到的。这项建议是环境地球化学和生物地球化学计划的一部分。它将由海洋科学处、化学处、地球科学处、分子和细胞生物科学处以及重大计划署多学科活动办公室共同资助。

9807662HeringRapid microbial oxidation of arsenic (As) from the +III to +V oxidation state has been observed in the geothermally-influenced surface waters of Hot Creek Gorge, located in California's Owens Valley. This project will investigate the biochemical mechanism and ecological aspects of this microbial process. Arsenic-oxidizing strain(s) will be isolated from a mixed culture, obtained from Hot Creek, that is currently being maintained in the P.I.'s laboratory and retains the capacity to oxidize As(III). Gene probes (based on 16s-rRNA sequences) will be developed for the mixed culture and used to guide the isolation of pure culture(s) of As(III) oxidizers, to perform genetic characterization and phylogenetic classification of pure strain(s), and to determine the spatial distribution of As(III) oxidizing bacteria at the field site in Hot Creek Gorge. Biochemical studies will be performed with the isolated As(III)-oxidizing strain(s) to determine the kinetics and mechanism of microbial As(III) oxidation. Coupled laboratory and field studies will be conducted to determine whether this process is associated with detoxification or with energy acquisition. If resources allow, a preliminary evaluation will be made of the ecological consequences of the abundant microbial colonization of the surfaces of aquatic macrophytes, which was observed in previous field studies.This proposal was part of the Environmental Geochemistry and Biogeochemistry program. It will be jointly funded by the Division of Ocean Sciences, Division of Chemistry, Division of Earth Sciences, Division of Molecular and Cellular Biosciences, and by the MPS Office of Multidisciplinary Activities.