HR: 09:30h
AN: OS11C-07    [Abstracts]
TI: Fine scale control of microbial communities in deep marine sediments that contain hydrates and high concentrations of methane
AU: * Colwell, F
EM: rcolwell@coas.oregonstate.edu
AF: Oregon State University, 104 COAS Admin Bldg, Corvallis, OR 97331-5503, United States
AU: Hangsterfer, A
EM: ahangste@ucsd.edu
AF: Scripps Institute of Oceanography, University of California, San Diego, La Jolla, CA 92093, United States
AU: Brodie, E
EM: elbrodie@lbl.gov
AF: Center for Environmental Biotechnology, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, United States
AU: Daly, R
EM: rdaly@berkeley.edu
AF: Dept of Plant and Microbial Biology, University of California, Berkeley, Berkeley, CA 94720, United States
AU: Holland, M
EM: melanie@geotek.co.uk
AF: GeoTek, Daventry, Northants, NN11 8RD, United Kingdom
AU: Briggs, B
EM: brigbran@hotmail.com
AF: Oregon State University, 104 COAS Admin Bldg, Corvallis, OR 97331-5503, United States
AU: Carini, P
EM: Pjcarini26@yahoo.com
AF: Oregon State University, 104 COAS Admin Bldg, Corvallis, OR 97331-5503, United States
AU: Torres, M
EM: mtorres@coas.oregonstate.edu
AF: Oregon State University, 104 COAS Admin Bldg, Corvallis, OR 97331-5503, United States
AU: Kastner, M
EM: mkastner@ucsd.edu
AF: Scripps Institute of Oceanography, University of California, San Diego, La Jolla, CA 92093, United States
AU: Long, P
EM: philip.long@pnl.gov
AF: Environmental Technology, Pacific Northwest National Laboratory, Richland, WA 99352, United States
AU: Schaef, H T
EM: todd.schaef@pnl.gov
AF: Environmental Technology, Pacific Northwest National Laboratory, Richland, WA 99352, United States
AU: Delwiche, M
EM: mark.delwiche@inl.gov
AF: Biotechnology, Idaho National Laboratory, Idaho Falls, ID 83415-2203, United States
AU: Winters, W
EM: bwinters@usgs.gov
AF: US Geological Survey, Woods Hole Science Center, Woods Hole, MA 02543, United States
AU: Riedel, M
EM: mriedel@eps.mcgill.ca
AF: Earth and Planetary Sciences, McGill University, Montreal, Que H3A 2A7, Canada
AB: Deep subseafloor sediments with high concentrations of organic carbon and microbially-generated methane contain microbial communities that play an important role in the biogeochemical cycling of carbon. However, we still have a limited understanding of the fine (centimeter) scale sediment properties (e.g., grain size, presence/absence of hydrates) that determine key microbial attributes in deep marine sediments. Our objective is to determine the quantity, diversity, and distribution of microbial communities in the context of abiotic properties in gas-rich marine sediments. DNA was extracted from deep marine sediments cored from various continental shelf locations including offshore India and the Cascadia Margin. Abiotic characterization of the same sediments included grain size analysis, chloride concentrations in sediment pore waters, and presence of hydrates in the sediments as determined by thermal anomalies. As in past studies of such systems, most of the samples yielded low levels of DNA (0.3-1.5 ng/g of sediment). Bacterial DNA appeared to be more easily amplified than archaeal DNA. Initial attempts to amplify DNA using primers specific for the methanogen functional gene, methyl- CoM-reductase, were unsuccessful. Infrequently, cores from relatively shallow sediments (e.g., 0.5 mbsf Leg 204, 1251B-1H) from central (Hydrate Ridge), and northern Cascadia (offshore Vancouver Island), and from India's eastern margin contained macroscopically visible, pigmented biofilms. One of these biofilms was composed of high concentrations of cell clusters when viewed microscopically. The predominant cells in the Hydrate Ridge biofilm were large (ca. 10 um) cocci and preliminary characterization of the 16S rDNA amplified and sequenced from this biofilm suggests the prevalence of a microbe with 97% similarity to mycobacteria. These discrete biofilm communities appear to be distinctive relative to the normally sparse distribution of cells in the sediments. By determining how the abiotic properties of deep marine sediments control the numbers and distribution of microbial communities that process organic matter we hope to provide better parameters for computational models that describe carbon cycling in these systems.
DE: 0414 Biogeochemical cycles, processes, and modeling (0412, 0793, 1615, 4805, 4912)
DE: 0448 Geomicrobiology
DE: 3000 MARINE GEOLOGY AND GEOPHYSICS
DE: 3004 Gas and hydrate systems
DE: 3036 Ocean drilling
SC: Ocean Sciences [OS]
MN: 2007 Fall Meeting