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Cold-Adapted Methanogens: Surviving Extreme Environments

Explore the survival mechanisms and adaptation strategies of cold-adapted methanogens living in extreme environments like Antarctica. Learn about their physiological limits and genomic analyses for insights into life's possibilities beyond Earth.

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Cold-Adapted Methanogens: Surviving Extreme Environments

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  1. Antarctic Extremophiles And Extraterrestrial Life Kevin R. Sowers Astrobiology Afternoon January 2005

  2. Archaea Crenarchaeota Euryarchaeota Halophiles Methanobacterium Methanobrevibacter Methanoplanus Methanothermus Methanospirillum Methanosarcina Hyperthermophiles Methanolobus Methanohalophilus Methanosaeta Methanococcus Methanopyrus Eukarya Bacteria

  3. Archaea are Extremophiles

  4. Alessandro Volta

  5. Marine Consortium Sowers & Ferry, 2002

  6. 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

  7. Photosynthesis

  8. Chemosynthesis

  9. Methanogen Growth Requirements • Mineral nutrients • e donors: H2 • e acceptor: CO2 • Anoxic atmosphere • Water

  10. 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

  11. 80% of Earth’s Biosphere < 5oC

  12. Mars Geology

  13. 4.5 b Present 3.8 b Water on Mars

  14. Deep Subsurface Microbiology Kaiser, 1995

  15. Ace Lake - Antarctica • marine salinity • maximum depth 25 m • anaerobic below 10-12 m • 2 to 3° C annually

  16. Cold-Adapted Methanogens Methanococcoides burtonii - Tmin 1.7˚C Tmax 30˚C Methanogenium frigidum - Tmin 0˚C Tmax: 18˚C

  17. Low Temperature Limits M. frigidum M. burtonii

  18. Simulated Arctic Conditions • Lowest temperature for growth • Effects of low temperature on metabolism • Effects of low temperature on survival

  19. Mesophile vs Psychrophile s

  20. Subzero Adaptation

  21. Genomic Analyses Methanogenium frigidum 1.6 Mb Methanococcoides burtonii 2.7 Mb (incomplete sequences)

  22. Cold Adaptation Mechanisms Cold-shock proteins Decreased protein surface charge

  23. What are the physiochemical limits? • Nutrient requirements • Temperature • Water • Radiation

  24. Contributors & Collaborators • - Sheridan MacAuley (COMB) • Rick Cavicchioli (UNSW) • Iain Neill Reid (STSI)

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