HR: 11:35h
AN: P52A-06    [Abstracts]
TI: Lake Vostok: An earthly analogue for the geomicrobiology on Europa
AU: * Priscu, J C
EM: jpriscu@montana.edu
AF: John C Priscu, Department of Land Resources & Environmental Sciences, Bozeman, MT 59717, United States
AU: Christner, B C
EM: xner@lsu.edu
AF: Brent C. Christner, Department of Biological Sciences 202 Life Sciences Bldg Louisiana State University, Baton Rouge, LA 70803, United States
AB: The recent discovery of more than 150 subglacial lakes beneath the Antarctic ice sheet has important implications in our search for liquid water and associated life on other icy worlds. The largest of these lakes is Lake Vostok, which has a surface area of 14000 square km and a depth of 1000 m, making it one of the largest lakes on Earth. Although we have yet to sample directly the liquid water from any of the Antarctic subglacial lakes, refrozen lakewater (accretion ice) has been sampled just above the surface of Lake Vostok. Genomic and geochemical analysis of this ice reveals that the surface lake water supports a microbial assemblage with a density approaching 1000 cells per milliliter. Sequencing and phylogenetic analysis of the 900 to 1000 base pair small subunit rRNA gene sequences obtained revealed a low diversity of clones that classify within the beta, gamma and delta subdivisions of the phylum Proteobacteria. Nearest phylogenetic neighbor analysis of these gene sequences imply that the lake contains an aerobic and anaerobic consortium of bacteria with metabolisms dedicated to iron and sulfur respiration or oxidation indicating that these metals play a role in the bioenergetics of microorganisms that occur in Lake Vostok. Sequence analysis further revealed that heterotrophic life in the lake can be sustained by chemolithotrophic production of new carbon supplemented by dissolved organic carbon released from the overlying ice sheet. Data obtained from orbiters have revealed that a deep ocean of liquid water lies under a thick chaotic ice cover on Europa where organic matter derived from comets and oxidants provided by radiation from Jupiter's magnetosphere may provide a habitat for life and a reservoir of endogenous and exogenous substances much like we observe in Lake Vostok. Future studies of Antarctic subglacial lake environments will play a crucial role in our understanding of life on Europa and other frozen worlds.
DE: 0410 Biodiversity
DE: 0448 Geomicrobiology
DE: 0463 Microbe/mineral interactions
DE: 0465 Microbiology: ecology, physiology and genomics (4840)
DE: 0716 Cryobiology (0475)
SC: Planetary Sciences [P]
MN: 2007 Fall Meeting