Syste

• Thaumarchaeota


  • Key genera: Nitrosopumilus, Nitrososphaera
  • Much smaller than Eukaryarchaeota
  • Abundant in marine waters and soil
  • Nitrifying Archaea (Nitrification): Oxidizes Ammonia to Nitrite
  • Uses CO2 as its sole carbon source, as do most nitrifying Bacteria
  • Extremophiles - Require specific conditions for them to grow
  • Thermophiles to Hyperthermophiles - Will not survive normal room temperature
  • Known through genetic analysis (metagenomic analysis) for challenging cultures
• Nanoarchaeota


  • Key Genera: Nanoarcheum
  • One of the smallest organism: both in cell size and genome size (100 - 400 nm, 1% the size of E. coli)
  • Cannot grow in pure culture
  • Can replicate when attached to its host, Ignicoccus hospitalis
  • N. equitans grows to 10 or more cells per Ignicoccus cell
  • Seems to live a parasitic lifestyle
  • Represented by one genus
  • One of the smallest not only in size but also in genome size (600,000 base pairs; Humans have 3.2 M)
  • Genes only for survival
  • Culturing - Cloned when only they are co-cultured with another Archaea (and grow)
• Korarchaeota


  • Key genus: Korarchaeum
  • Also called as Secret Filament
  • Korarchaeum cryptofilum: Obligately anaerobic chemoorganotroph, Hyperthermophile, Cells are long, thin filaments (not rods, similar to mycelium), Lacks many core genes, Depends on other members of hot springs community
• Crenarchaeota


  • Are chemolithotrophic autotrophs (habitats devoid of photosynthetic life)
  • Only primary producers in harsh environments (hydrothermal vents)
  • Mostly hyperthermophiles
  • Many hyperthermophilic crenarchaeotes grow chemolithotrophically under anoxic conditions with H2 as the electron donor and S0 or NO3- as the electron acceptor
• Key genera of Crenarchaeota from Terrestrial Volcanic Habitats


  • Sulfolobus
  • Acidianus
  • Thermoproteus
  • Pyrobaculum
• Sulfolobales


  • Sulfolobus: Grows in sulfur-rich acidic hot springs, Aerobic chemolithotrophs that oxidize reduced sulfur or iron
  • Acidianus: Also lives in acidic sulfur hot springs, Uses elemental sulfur both aerobically and anaerobically
• Crenarchaeota from Submarine Volcanic Habitats

  • Key genera: Pyrodictium, Pyrolobus, Ignicoccus, Staphylothermus
  • Shallow-water thermal springs and deep sea hydrothermal vents harbor the most thermophilic of all known Archaea
  • Hyperthermophiles
  • Hydrothermal vents - found in the sea floor, steam-ish, Black and steam because of hydrogen sulfide, Located at volcanic habitats such as tectonic plates
• Pyrodictium


  • Has a min temperature of 82°C, optimum growth at 105°C maximum temperature at 110°C
  • Both organotrophic/lithotrophic S and H2 are the most common electron sources
• Desulfurococcales

  Desulfurococcales with growth temperature optimum >100°C
• Staphylothermus marinus


  Spherical cells, About 1 mm in diameter, Forms aggregates of up to 100 cells, Chemoorganotroph that grows optimally at 92°C
• Asgard Archaea


  • New archaeal group that is related to the host cell from which eukaryotic cells evolved
  • It bridged the gap between Archaea and Eukarya
  • Has not been grown in culture
  • Presence was confirmed through metagenomic analysis of samples from hydrothermal vents not in pure culture
  • Includes: Lokiarcheaota, Thorarchaeota, Odinarcheota, Heimdallarcheota
• Lokiarcheaota

  First found in Loki's castle - A hydrothermal vent system around the Atlantic, Temperature is until 300 degrees Celsius, Contains elemental sulfur and sulfur-oxidizing organism