HR: 0800h
AN: B21D-0909    [Abstracts]
TI: Carbon Isotope Signatures of Microbial Mats in the Jackson Mountain Hot Spring, Nevada
AU: * Mills, G L
EM: mills@srel.edu
AF: Savannah River Ecology Laboratory, University of Georgia, Aiken, SC 29802 United States
AU: Li, Y
EM: li@srel.edu
AF: Savannah River Ecology Laboratory, University of Georgia, Aiken, SC 29802 United States
AU: Jones, M
EM: jones@srel.edu
AF: Savannah River Ecology Laboratory, University of Georgia, Aiken, SC 29802 United States
AU: Paddock, L
EM: paddock@srel.edu
AF: Savannah River Ecology Laboratory, University of Georgia, Aiken, SC 29802 United States
AU: Romanek, C S
EM: romanek@srel.edu
AF: Savannah River Ecology Laboratory, University of Georgia, Aiken, SC 29802 United States
AU: Zhang, C L
EM: zhang@srel.edu
AF: Savannah River Ecology Laboratory, University of Georgia, Aiken, SC 29802 United States
AU: Wiegel, J
EM: jwiegel@uga.edu
AF: Department of Microbiology, University of Georgia, Athens, GA 30602-2605 United States
AB: The long-term goal of this study is to determine the diversity, ecological function, and CO2 fixation pathways of novel microorganisms in Nevada hot springs. A survey of 16 hot springs in Nevada in May 2004 showed large variations in pH (5.5-9.4) and temperature (36-96øC), which may have significant impact on microbial diversity and primary production by autotrophs. In this study, we select the Jackson Mountain hot spring for a detailed carbon-isotope study along a temperature-and-pH gradient during the formation of travertine (carbonate) deposits. Field measurements indicated that temperature decreased from 68.8-72.3 øC at the vents to 44 øC at the end of slope; the corresponding pH increased from 7.3-7.4 at the vents to 8.3 at the base of slope. Isotopic compositions of dissolved inorganic carbon increased slightly from -3.77 per mil at the vent to -3.2 per mil down gradient. Mat materials were collected along the temperature-and-pH gradient for analyses of bacterial phospholipid fatty acids (PLFA). We expect that temperature will be a major control on the distribution of PLFA in the changing microbial communities because microbial lipid compositions are sensitive to temperature variation. Isotopic fractionations between lipid biomarkers and total biomass are expected to provide insight about the dominant CO2 fixation pathways in different microbial communities growing in different temperature environments.
DE: 8424 Hydrothermal systems (8135)
DE: 4805 Biogeochemical cycles (1615)
DE: 4870 Stable isotopes
DE: 1055 Organic geochemistry
DE: 0400 Biogeosciences
SC: Biogeosciences [B]
MN: 2004 AGU Fall Meeting