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Analysis of atmospheric oxygen tolerance in methanogens

Analysis of atmospheric oxygen tolerance in methanogens. By Jill Jackson. Introduction. Methanogens are: Archaea Anaerobic Extremophiles. CO 2 + 4 H 2  CH 4 + 2H 2 O. Why study methanogens?. Martian Conditions Dry Cold Oxidizing Low pressure Abundance of CO 2. Purpose.

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Analysis of atmospheric oxygen tolerance in methanogens

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  1. Analysis of atmospheric oxygen tolerance in methanogens By Jill Jackson

  2. Introduction Methanogens are: • Archaea • Anaerobic • Extremophiles • CO2 + 4 H2 CH4 + 2H2O

  3. Why study methanogens? Martian Conditions • Dry • Cold • Oxidizing • Low pressure • Abundance of CO2

  4. Purpose • Can Methanosarcina barkeri and Methanothermobacter wolfeii recover after atmospheric O2 exposure? • True oxygen tolerance or effect of reducing agent? • How do they survive?

  5. Methods • Optical density measurements • Oxygen exposure times: 0, 2, 3, 4, 5, and 8 • hours • Cultures exposed to atmospheric O2 both • with and without Na2S

  6. Methods (cont.) • Incubation in ideal conditions • Analysis using GC (gas chromatography)

  7. Results: M. wolfeii Optical Density Measurements

  8. Results: M. barkeri Optical Density Measurements

  9. Results Summary • Role of Na2S • Implications of expanded research capabilities • Two other possible factors • SOD • Cellular Aggregation • Do some strains of methanogens have a limited intrinsic tolerance to oxygen?

  10. What is an SOD? • Superoxide dismutase • Role in oxidative stress • O2- radical damage • Findings by Brioukhanov et. al.

  11. Cellular Aggregation Findings by Kato et. al. indicate increased O2 tolerance of M. barkeri in aggregates

  12. Conclusion • Methanogens exhibited survival in the absence of Na2S • Some strains of methanogens have a limited intrinsic tolerance to oxygen • Aggregation also likely affects survival • Shorter exposure, faster recovery

  13. Future Work • Analysis of oxygen tolerance at various optical densities • Oxygen tolerance analysis of additional strains of methanogens

  14. References • Brioukhanov, A., Netrusov, A., Sordel, M., Thauer, R.K., and S.Shima. 2000. Protection of Methanosarcina barkeri against oxidative stress: identification and characterization of an iron superoxide dismutase. Arch. Microbiol. 174: 213-216. • Cannio, R., Fiorentino, G., Morana, A., Rossi, M., and S. Bartolucci. 2000. Oxygen: Friend of Foe? Archaeal Superoxide Dismutases in the Protection of Intra- and Extracellular Oxidative Stress. Frontiers in Bioscience. 5:768-779. • Kato, M.T., Field, J.A., and G. Lettinga. 1997. Anaerobe Tolerance to Oxygen and the Potentials of Anaerobic and Aerobic Cocultures for Wastewater Treatment. Braz. J. Chem. Eng. 14. • Kral, T.A., Bekkum, C.R., and McKay, C.P. 2004. Growth of Methanogens on a Mars Soil Simulant. Orig. of Life and Ev. of the Biosphere. 34: 615-626. • Reeve, J.N. 1992. Molecular Biology of Methanogens. Annu. Rev. Microbiol., 46: 165-191. • http://dutch.phys.strath.ac.uk/CommPhys2001Exam/David_Speirs/climateandweather.htm

  15. Photos • http://www.genomenewsnetwork.org/articles/07_03/extremo.shtml • www.ccfc.ca/English/ images/gut.gif • www.myeloperoxidase.com/ FeSOD/images/FeSOD.jpg • www.backdrops.net/ Rent%20Backdrops%20p.1.htm • http://www.jpl.nasa.gov/news/features.cfm?feature=533 • www.myeloperoxidase.com/ FeSOD/planta.html • http://genome.jgi-psf.org/draft_microbes/metba/metba.home.html • http://biology.kenyon.edu/Microbial_Biorealm/archaea/methanothermobacter/methanothermobacter.html

  16. Acknowledgements

  17. Questions?

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