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Antarctic Extremophiles And Extraterrestrial Life. Kevin R. Sowers. Astrobiology Afternoon January 2005. Archaea. Crenarchaeota. Euryarchaeota. Halophiles. Methanobacterium. Methanobrevibacter. Methanoplanus. Methanothermus. Methanospirillum. Methanosarcina. Hyperthermophiles.
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Antarctic Extremophiles And Extraterrestrial Life Kevin R. Sowers Astrobiology Afternoon January 2005
Archaea Crenarchaeota Euryarchaeota Halophiles Methanobacterium Methanobrevibacter Methanoplanus Methanothermus Methanospirillum Methanosarcina Hyperthermophiles Methanolobus Methanohalophilus Methanosaeta Methanococcus Methanopyrus Eukarya Bacteria
Marine Consortium Sowers & Ferry, 2002
Orders of Methanogenic Archaea • Methanobacteriales H2/CO2 • Methanococcales H2/CO2 • Methanomicrobiales H2/CO2 • Methanopyrales H2/CO2 • Methanosarcinales H2/CO2,CH3COOH,CH3OH, MMA,DMA,TMA,DMS 4H2 + CO2 CH4 + 2H2O
Methanogen Growth Requirements • Mineral nutrients • e donors: H2 • e acceptor: CO2 • Anoxic atmosphere • Water
Life in Extreme Environments Mars • Surface gravity = 3.8 m s-2 (~ 1/3rd Earth’s gravity) • Current surface temperatures – –87 to 25o C (atmosphere) -70 to 10o C (soil temperatures) • Atmospheric composition – predominantly CO2
4.5 b Present 3.8 b Water on Mars
Deep Subsurface Microbiology Kaiser, 1995
Ace Lake - Antarctica • marine salinity • maximum depth 25 m • anaerobic below 10-12 m • 2 to 3° C annually
Cold-Adapted Methanogens Methanococcoides burtonii - Tmin 1.7˚C Tmax 30˚C Methanogenium frigidum - Tmin 0˚C Tmax: 18˚C
Low Temperature Limits M. frigidum M. burtonii
Simulated Arctic Conditions • Lowest temperature for growth • Effects of low temperature on metabolism • Effects of low temperature on survival
Genomic Analyses Methanogenium frigidum 1.6 Mb Methanococcoides burtonii 2.7 Mb (incomplete sequences)
Cold Adaptation Mechanisms Cold-shock proteins Decreased protein surface charge
What are the physiochemical limits? • Nutrient requirements • Temperature • Water • Radiation
Contributors & Collaborators • - Sheridan MacAuley (COMB) • Rick Cavicchioli (UNSW) • Iain Neill Reid (STSI)