1. Archaea

4. Gram Staining Archaea (Not for the same reasons as Bacteria.)+ -
* Gram+ cell wall like with Gram+ Bacteria, but different biochemical composition that peptidoglycan.
* Gram– due to glycoprotein surface layer not an
outer membrane.
* Some with NO cell wall!

5. Pseudomurein (Murein = NAG-NAM of peptidoglycan in Bacteria)
Pseudomurein (Murein = NAG-NAM of peptidoglycan in Bacteria) * Insensitive to penicillin. * NAM replaced by NAT * Unique side-chain peptide cross-links.

6. Lipid Differences:. Hydrocarbons not fatty acids
Lipid Differences: * Hydrocarbons not fatty acids * Ether linked to glycerol not ester linked

7. Two leaves (bilayer) of C20 diethers
Which is most likely that for an extreme thermophile?
Single layer of rigid C40 tetraethers

8. Unique Means of Autotrophy
* No Calvin Cycle
* Reversed Modified TCA Cycle
* Reductive Acetyl-CoA

9. Methanogens

10. Methanogens Obligate anaerobes dependent on fermentation bacteria.
Chemoheterotrophic:
Acetoclastic
Acetate to CO2 and methane
Chemoautotrophic:
H2 or formate as energy & electron source
CO2 to methane and other cellular components

12. Methanogenesis Pathway
MCR protein is a 3 component complex; Component C is made of 3 polypeptide subunits (α,β,γ) encoded on mcrA, mcrB, and mcrG genes.

13. Methanogen Habitats

14. Aerobic respiration yields greatest energy due to very positive O2 redox potential.
Without O2, anaerobic respiration uses alternate terminal electron acceptors in the order of decreasing redox potential.
E = +820 mV
E = +420 mV
E = -200 mV
E = -240 mV
Methanogenesis

15. Anearobic Complex Organic Matter Degradation
Hydrolysis
Fermentation
Acetogenesis
Sulfate Reduction
Methanogenesis

16. Carbon Cycle
Methylotrophy

17. Methane Production - Consumption

18. Subsurface Methane Production: Methanogens (shallower)
(12C reacts faster than 13C)
Geothermal (deeper)

19. Sewage Treatment Plants

20. Global Importance Potent Greenhouse Gas
Over 30x more potent than carbon dioxide.
Increasing emissions by 1% per year.
Increased by more nitrogen and carbon dioxide.
Primary culprits:
Wetlands (N)
Termites (N)
Fossil Fuel (MM)
Rice paddies (MM)
Wastes (MM)
Rumen and Enteric (N/MM)
Deforestation Burning (MM)