Archaea methanogens
- 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) * Insensitive to penicillin. * NAM replaced by NAT * Unique side-chain peptide cross-links.
- 6. Lipid Differences: * Hydrocarbons not fatty acids * Ether linked to glycerol not ester linked
- 7. Two leaves (bilayer) of C20 diethers Single layer of rigid C40 tetraethers Which is most likely that for an extreme thermophile?
- 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.
- 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 = -240 mV Methanogenesis E = +820 mV E = +420 mV E = -200 mV
- 15. Anearobic Complex Organic Matter Degradation 1) Hydrolysis 2) Fermentation 3) Acetogenesis 4) Sulfate Reduction 5) Methanogenesis
- 17. Methane Production - Consumption
- 18. Subsurface Methane Production: Methanogens (shallower) (12 C reacts faster than 13 C) Geothermal (deeper)
- 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)