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©2004 Howard Hughes Medical Institute Extremophiles 101 Mark E. Nielsen, Ph.D. Science Education Fellow Educational Resources Group Howard Hughes Medical.

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Presentation on theme: "©2004 Howard Hughes Medical Institute Extremophiles 101 Mark E. Nielsen, Ph.D. Science Education Fellow Educational Resources Group Howard Hughes Medical."— Presentation transcript:

1 ©2004 Howard Hughes Medical Institute Extremophiles 101 Mark E. Nielsen, Ph.D. Science Education Fellow Educational Resources Group Howard Hughes Medical Institute All text is Times New Roman Presentation Title:24/25 24 before; Bold, White, All Caps Subtitle: 22/25, 24before, White. Italic Name: 24/25, 24 before, bold, White Title: 14/25, 24 before, White Date: 14/25, 24 before, White Text Box Position, from top left: hz: ” vt: 2.93 ”

2 ©2004 Howard Hughes Medical Institute 6 July 2012 Extremophiles 101 – Astrobiology Laboratory Institute for Instructors Outline for today’s talk Introduction and few definitions Tour of extreme environments biological ramifications coping mechanisms interesting highlights Practical implications/considerations

3 ©2004 Howard Hughes Medical Institute 6 July 2012 Extremophiles 101 – Astrobiology Laboratory Institute for Instructors What is normal and what is extreme? Physical extremes: - Temperature - Pressure - Radiation Geochemical extremes: - pH (acidity levels)‏ - Salinity - Desiccation - Oxygen species - Redox potential For any particular property (T, pH, salinity) extreme values are values far from the typical range for human life

4 ©2004 Howard Hughes Medical Institute 6 July 2012 Extremophiles 101 – Astrobiology Laboratory Institute for Instructors What is normal and what is extreme? Physical extremes: - Temperature - Pressure - Radiation Geochemical extremes: - pH (acidity levels)‏ - Salinity - Desiccation - Oxygen species - Redox potential For any particular property (T, pH, salinity) extreme values are values far from the typical range for human life

5 ©2004 Howard Hughes Medical Institute 6 July 2012 Extremophiles 101 – Astrobiology Laboratory Institute for Instructors Why cover extremophiles in an astrobiology workshop? Mars Europa

6 ©2004 Howard Hughes Medical Institute 6 July 2012 Extremophiles 101 – Astrobiology Laboratory Institute for Instructors Diversity Who are the extremophiles?

7 ©2004 Howard Hughes Medical Institute 6 July 2012 Extremophiles 101 – Astrobiology Laboratory Institute for Instructors Environmental Extremes – What do they mean to the organisms? Temperature protein denaturation, reduced solubility of gases, Increases fluidity of membranes, chlorophyll degrades at 75 °C ice formation (physical stress), lack of liquid water (chemical stress)

8 ©2004 Howard Hughes Medical Institute 6 July 2012 Extremophiles 101 – Astrobiology Laboratory Institute for Instructors Cell membranes Membrane fluidity is related to composition of fatty acids

9 ©2004 Howard Hughes Medical Institute 6 July 2012 Extremophiles 101 – Astrobiology Laboratory Institute for Instructors Other high temperature adaptations Histones – proteins that bind to DNA Different chemical bonds

10 ©2004 Howard Hughes Medical Institute 6 July 2012 Extremophiles 101 – Astrobiology Laboratory Institute for Instructors Environmental Extremes – What do they mean to the organisms?

11 ©2004 Howard Hughes Medical Institute 6 July 2012 Extremophiles 101 – Astrobiology Laboratory Institute for Instructors Environmental Extremes – What do they mean to the organisms? Radiation = Energy in transit as particles (e.g., electrons, neutrons, protons, alpha particles) or waves (gamma rays, x-rays, UV) Rarely occur but high UV exposure can occur DNA damage directly or indirectly from ROS Deinococcus radiodurans "A lethal level of radiation for humans is about 700 rads. The bacterium Deinococcus radiodurans can withstand 1.5 million... There’s never been anything like this level of natural radioactivity on earth in its 4.6 billion year history, so how can we explain the evolution of such a capability?"

12 ©2004 Howard Hughes Medical Institute 6 July 2012 Extremophiles 101 – Astrobiology Laboratory Institute for Instructors Reactive Oxygen Species Early Earth may have had H 2 O 2 rain Organisms evolved anti-oxidants to deal with this super oxide dismutase/reductase catalase peroxidase Oxygen is very corrosive to organic chemical bonds. Mechanisms evolved very early to deal with this

13 ©2004 Howard Hughes Medical Institute 6 July 2012 Extremophiles 101 – Astrobiology Laboratory Institute for Instructors Environmental Extremes – What do they mean to the organisms? Pressure: Boiling pt. of water increases Volume changes Gravity – changes in biomass production rates, changes in membrane permeability

14 ©2004 Howard Hughes Medical Institute 6 July 2012 Extremophiles 101 – Astrobiology Laboratory Institute for Instructors Environmental Extremes Desiccation: Water is an unusual fluid that makes it unique and critical for life. Issues: irreversible phase changes to lipids, proteins, and nucleic acids through denaturation and chemical reactions (Maillard reactions)

15 ©2004 Howard Hughes Medical Institute 6 July 2012 Extremophiles 101 – Astrobiology Laboratory Institute for Instructors Environmental Extremes pH Lots of H + can denature proteins (ceviche) Acidophiles thrive at low pH Alkaliphiles thrive at high pH (an equally challenging environment) protons are scarce so energy tough to come by Ferroplasma acidarmanus

16 ©2004 Howard Hughes Medical Institute 6 July 2012 Extremophiles 101 – Astrobiology Laboratory Institute for Instructors Environmental Extremes pH Lots of H + can denature proteins (ceviche) Acidophiles thrive at low pH Alkaliphiles thrive at high pH (an equally challenging environment) protons are scarce so energy tough to come by

17 ©2004 Howard Hughes Medical Institute 6 July 2012 Extremophiles 101 – Astrobiology Laboratory Institute for Instructors Environmental Extremes Salinity Halophiles – organisms with adaptations to grow in high salt conditions (up to saturation!). Adaptation: Increasing osmotica intracellularly (e.g., K +, betaine, glutamate, sucrose) Dunaliella salina Halobacterium (actually Archaea)

18 ©2004 Howard Hughes Medical Institute 6 July 2012 Extremophiles 101 – Astrobiology Laboratory Institute for Instructors Summary of extremophiles and their environments

19 ©2004 Howard Hughes Medical Institute 6 July 2012 Extremophiles 101 – Astrobiology Laboratory Institute for Instructors Biotechnological relevance ProcessBiomoleculeAdvantageSource PCR ReactionTaq polymerase Stable at high temperatures Thermophiles Paper bleachingxylanases Decreases amount of bleach required Thermophiles Degradation of polymers in detergents Proteases Amylases Lipases Improved performance of detergents and stable at high pH Psychrophiles and alkaliphiles Cheese maturation and dairy processing Proteases Stable at low temperatures Psychrophiles Biofuel productionCellulases Stable at high temp. versatile Thermophiles Biofuel productionFatty acids/lipids Stable at high temp/low pH Thermophilic microalgae

20 ©2004 Howard Hughes Medical Institute 6 July 2012 Extremophiles 101 – Astrobiology Laboratory Institute for Instructors Biotechnological relevance Thermus aquaticus – DNA polymerase

21 ©2004 Howard Hughes Medical Institute 6 July 2012 Extremophiles 101 – Astrobiology Laboratory Institute for Instructors Biofuels – A challenge and an opportunity

22 ©2004 Howard Hughes Medical Institute 6 July 2012 Extremophiles 101 – Astrobiology Laboratory Institute for Instructors Biofuels – A challenge and an opportunity Bioelectrosynthesis Microbes can accept electrons from solid surfaces to fix carbon

23 ©2004 Howard Hughes Medical Institute 6 July 2012 Extremophiles 101 – Astrobiology Laboratory Institute for Instructors Biofuels – A challenge and an opportunity

24 ©2004 Howard Hughes Medical Institute 6 July 2012 Extremophiles 101 – Astrobiology Laboratory Institute for Instructors Bringing it back to astrobiology

25 ©2004 Howard Hughes Medical Institute 6 July 2012 Extremophiles 101 – Astrobiology Laboratory Institute for Instructors Lake Vostoc: A model for Life on Europa?

26 ©2004 Howard Hughes Medical Institute 6 July 2012 Extremophiles 101 – Astrobiology Laboratory Institute for Instructors A good Source Nature, Vol. 409, February 2001

27 ©2004 Howard Hughes Medical Institute 6 July 2012 Extremophiles 101 – Astrobiology Laboratory Institute for Instructors Questions? temperatures as low as -200 °C (-328 °F) and as high as 151 °C (304 °F); freezing and/or thawing processes; changes in salinity; lack of oxygen; lack of water; levels of X-ray radiation 1000x the lethal human dose; some noxious chemicals; boiling alcohol; low pressure of a vacuum; high pressure (up to 6x the pressure of the deepest part of the ocean)


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