Archaea Microbiology: Extremophiles

Archaea Microbiology

Extremophiles

• Definition: Organisms that thrive in extreme environments with conditions such as high temperatures, high salinity, high pressure, and high acidity.
• Examples of archaeal extremophiles:
  • Thermococci: thrive in temperatures above 80°C
  • Halophiles: thrive in high salt environments (e.g. salt lakes, salt mines)
  • Piezophiles: thrive in high-pressure environments (e.g. deep-sea vents)
  • Acidophiles: thrive in acidic environments (e.g. hot springs, acidic mines)

Methanogenesis

• Definition: The process of producing methane as a byproduct of metabolism
• Methanogenic archaea:
  • Found in anaerobic environments (e.g. swamps, marshes, digestive systems)
  • Use CO2 as their final electron acceptor in the electron transport chain
  • Produce methane as a byproduct of energy production
  • Examples: Methanococcus, Methanobacterium

Archaeal Membranes

• Composition: Unique lipids with ether linkages instead of ester linkages
• Characteristics:
  • More stable and resistant to extreme temperatures and pH
  • Allow for the maintenance of membrane structure and function in extreme environments
  • Differ from bacterial membranes in their composition and function

Characteristics of Archaea

• Prokaryotic cells
• Lack of peptidoglycan (cell wall component)
• Unique membrane lipids
• Ability to thrive in extreme environments
• Genetic distinctness from bacteria and eukarya

Cell Wall Structures

• Lack of peptidoglycan (cell wall component) *Presence of pseudopeptidoglycan (similar to peptidoglycan but with different sugar molecules)
• S-layer: a protein layer that provides structural support and protection
• Glycoproteins: carbohydrate-modified proteins that provide additional structural support

Archaea Microbiology

Extremophiles

• Thrive in extreme environments with conditions such as high temperatures, high salinity, high pressure, and high acidity.
• Examples include:
  • Thermococci, which thrive in temperatures above 80°C.
  • Halophiles, which thrive in high salt environments (e.g.salt lakes, salt mines).
  • Piezophiles, which thrive in high-pressure environments (e.g.deep-sea vents).
  • Acidophiles, which thrive in acidic environments (e.g.hot springs, acidic mines).

Methanogenesis

• Process of producing methane as a byproduct of metabolism.
• Occurs in anaerobic environments (e.g.swamps, marshes, digestive systems).
• Methanogenic archaea use CO2 as their final electron acceptor in the electron transport chain.
• Produce methane as a byproduct of energy production.
• Examples include Methanococcus and Methanobacterium.

Archaeal Membranes

• Composed of unique lipids with ether linkages instead of ester linkages.
• More stable and resistant to extreme temperatures and pH.
• Allow for the maintenance of membrane structure and function in extreme environments.
• Differ from bacterial membranes in their composition and function.

Characteristics of Archaea

• Prokaryotic cells.
• Lack peptidoglycan (cell wall component).
• Have unique membrane lipids.
• Ability to thrive in extreme environments.
• Genetically distinct from bacteria and eukarya.

Cell Wall Structures

• Lack peptidoglycan (cell wall component).
• Contain pseudopeptidoglycan (similar to peptidoglycan but with different sugar molecules).
• Have an S-layer, a protein layer that provides structural support and protection.
• Contain glycoproteins, carbohydrate-modified proteins that provide additional structural support.