HR: 13:55h
AN: V23D-02    [Abstracts]
TI: Towards Determining the Upper Temperature Limit to Life
AU: * Kelley, D S
EM: dskelley@u.washington.edu
AF: University of Washington, School of Oceanography, Box 357940, Seatle, WA 98195, United States
AU: Girguis, P R
EM: pgirguis@oeb.harvard.edu
AF: Harvard University, Biological Labs, 16 Divinity Ave, Cambridge, MA 02138, United States
AU: Wheat, G
EM: wheat@mbari.org
AF: University of Fairbanks, P.O. Box 475, Moss Landing, CA 95039, United States
AU: Cordes, E
EM: ecordes@oeb.harvard.edu
AF: Harvard University, Biological Labs, 16 Divinity Ave, Cambridge, MA 02138, United States
AU: Schrenk, M O
EM: mschrenk@ciw.edu
AF: Carnegie Institution of Washington, Geophysical Laboratory, 5251 Broad Branch Road. NW, Washington, DC 20015, United States
AU: Lin, M
EM: mhl@u.washington.edu
AF: University of Washington, School of Oceanography, Box 357940, Seatle, WA 98195, United States
AU: Baross, J A
EM: jbaross@u.washington.edu
AF: University of Washington, School of Oceanography, Box 357940, Seatle, WA 98195, United States
AU: Delaney, J R
EM: jdelaney@u.washington.edu
AF: University of Washington, School of Oceanography, Box 357940, Seatle, WA 98195, United States
AB: Determining the upper temperature limit to life is key to defining the habitable regions of our planet, understanding the origin of life, and it is an important guide in our search for life elsewhere. Recent studies of hydrothermal vent environments challenge previous known limits with laboratory cultures reaching 121°C, and evidence for microbial communities even within the hottest interior walls of black smoker chimneys. Studies focused on examining the most extreme conditions under which life thrives, survives, and expires are inherently challenging because of the difficulty in directly accessing the hottest portions of the deep biosphere and because of our inability to adequately reproduce in situ environmental conditions in the laboratory. To begin to address these challenges, novel in situ microbial incubators were deployed into the walls of active black smoker chimneys on the Endeavour Segment of the Juan de Fuca Ridge. The incubators contained 3-4 discrete chambers. Each chamber hosted nine thermocouples and some incubators contained OsmoSamplers for continuous time-series sampling of hydrothermal fluids within the chambers. The incubators were deployed for periods of 1.5 months to one year, with reinstrumentation of some sites annually since 2002. The incubators routinely record sharp and well defined temperature gradients within each of the chambers that vary from near seawater values in the most outer chambers to end member conditions (200°C) within the interior walls. Fourier transform analyses indicate that diurnal and semi-diurnal tidal forcing results in small temperature perturbations in all chambers; much longer term perturbations (tens of days) that reach up to 50°C likely reflect localized fracturing events in the subseafloor and fresh injection of hotter fluids. Co-registered microbial community analyses of material recovered from newly precipitated mineral surfaces from within the chambers on cm-scales across the temperature and chemical gradients show a high diversity of 16S archaeal phlotypes and evidence for cells within the hottest portions of the chambers. These initial results again bring into question whether life can exist at temperature in excess of 150°C. It is a tribute to John Holloway that we were able to conduct this study. The authors give him a heartfelt thanks for his enthusiastic encouragement during this project and especially for his numerous pointed and enthusiastic reviews, which where likely instrumental in getting this project funded.
UR: http://www.visions05.washington.edu/science/investigations/micro_survival.html
DE: 0448 Geomicrobiology
DE: 0450 Hydrothermal systems (1034, 3017, 3616, 4832, 8135, 8424)
DE: 0452 Instruments and techniques
DE: 3614 Mid-oceanic ridge processes (1032, 8416)
DE: 3616 Hydrothermal systems (0450, 1034, 3017, 4832, 8135, 8424)
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2007 Fall Meeting