1. 19.1 Phylogenetic and Metabolic Diversity of Archaea Archaea share many characteristics with both Bacteria and Eukarya Archaea are split into two major groups (Figure 19.1) –Crenarchaeota –Euryarchaeota © 2012 Pearson Education, Inc.

2. 19.1 Phylogenetic and Metabolic Diversity of Archaea Bioenergetics and intermediary metabolism of Archaea are similar to those found in Bacteria –Except some Archaea use methanogenesis –Autotrophy via several different pathways is widespread in Archaea © 2012 Pearson Education, Inc.

3. Figure 19.1 Extreme halophiles Extreme acidophiles Hyperthermophiles Crenarchaeota Marine Crenarchaeota Pyrodictium Thermoproteus Sulfolobus Desulfurococcus Euryarchaeota Marine Euryarchaeota Halophilic methanogen Halobacterium Halococcus Natronococcus Archaeoglobus Methanobacterium Methanocaldococcus Methanothermus Thermococcus/ Pyrococcus Nanoarchaeum Methanopyrus Methanosarcina Methanospirillum Thermoplasma Ferroplasma Picrophilus © 2012 Pearson Education, Inc.

4. II. Euryarchaeota Euryarchaeota –Physiologically diverse group of Archaea –Many inhabit extreme environments Examples: high temperature, high salt, high acid © 2012 Pearson Education, Inc.

5. 19.2 Extremely Halophilic Archaea Haloarchaea Key genera: Halobacterium, Haloferax, Natronobacterium –Extremely halophilic Archaea –Have a requirement for high salt concentrations Typically require at least 1.5 M (~9%) NaCl for growth –Found in artificial saline habitats (e.g., salted foods), solar salt evaporation ponds, and salt lakes (Figure 19.2) © 2012 Pearson Education, Inc.

6. Figure 19.2 © 2012 Pearson Education, Inc.

7. 19.2 Extremely Halophilic Archaea Haloarchaea –Reproduce by binary fission –Do not form resting stages or spores –Most are nonmotile –Most are obligate aerobes –Possess adaptations to life in highly ionic environments Cell wall is composed of glycoprotein and stabilized by Na + (Figure 19.3) © 2012 Pearson Education, Inc.

8. 19.2 Extremely Halophilic Archaea Water Balance in Extreme Halophiles –Halophiles need to maintain osmotic balance This is usually achieved by accumulation or synthesis of compatible solutes –Halobacterium species instead pump large amounts of K + into the cell from the environment Intracellular K + concentration exceeds extracellular Na + concentration and positive water balance is maintained © 2012 Pearson Education, Inc.

9. 19.2 Extremely Halophilic Archaea Proteins of halophiles –Are highly acidic –Contain fewer hydrophobic amino acids and lysine residues © 2012 Pearson Education, Inc.

10. 19.2 Extremely Halophilic Archaea Some haloarchaea are capable of light-driven synthesis of ATP (Figure 19.4) –Bacteriorhodopsin Cytoplasmic membrane proteins that can absorb light energy and pump protons across the membrane © 2012 Pearson Education, Inc. Animation: Bacteriorhodopsin and Light Mediated ATP Synthesis Animation: Bacteriorhodopsin and Light Mediated ATP Synthesis

11. Figure 19.4 Out In Membrane Bacteriorhodopsin ATPase © 2012 Pearson Education, Inc.

12. 19.3 Methanogenic Archaea Methanogens (Figure 19.5) –Key genera: Methanobacterium, Methanocaldococcus, Methanosarcina Microbes that produce CH 4 Found in many diverse environments Taxonomy based on phenotypic and phylogenetic features Process of methanogenesis first demonstrated over 200 years ago by Alessandro Volta © 2012 Pearson Education, Inc.

13. Figure 19.5 © 2012 Pearson Education, Inc.

14. 19.3 Methanogenic Archaea Diversity of Methanogens –Demonstrate diversity of cell wall chemistries (Figure 19.6 and Figure 19.7) Pseudomurein (e.g., Methanobacterium) Methanochondroitin (e.g., Methanosarcina) Protein or glycoprotein (e.g., Methanocaldococcus) S-layers (e.g., Methanospirillum) © 2012 Pearson Education, Inc.

15. Figure 19.6 © 2012 Pearson Education, Inc.

16. Figure 19.7 © 2012 Pearson Education, Inc.

17. 19.5 Thermococcales and Methanopyrus Three phylogenetically related genera of hyperthermophilic Euryarchaeota: –Thermococcus –Pyrococcus –Methanopyrus Comprise a branch near root of archaeal tree © 2012 Pearson Education, Inc.

18. 19.5 Thermococcales and Methanopyrus Thermococcales –Distinct order that contains Thermococcus and Pyrococcus (Figure 19.11) –Indigenous to anoxic thermal waters –Highly motile © 2012 Pearson Education, Inc.

19. Figure 19.11 © 2012 Pearson Education, Inc.

20. Figure 19.16 © 2012 Pearson Education, Inc.