Archaebacteria are one of the six kingdoms of life: plants, animals, protists, fungi, eubacteria and archaebacteria.
One type of archaebacteria is crenarchaeota, which can live in extreme temperatures or acidity.
Another type of archaebacteria is euryarchaeota, which include ones who produce methane or live in water with a high salt content.
Methanogens are archaeabacteria that produce methane gas as a metabolic byproduct in areas of low oxygen content. They are found in human intestines, wetlands, hot springs or geothermal vents.
Examples include these strains:
Halobacteriaceae are archaebacteria that live in highly-saturated salty environments.
Thermophiles are archaebacteria that live at extremely hot temperatures, as in geothermal environments.
Examples of species of the genus Sulfolobus include:
Psychrophiles are archaebacteria that thrive in extremely cold temperatures from a polar region to the deep sea.
These different examples of archaebacteria have unusual cell walls, membranes, ribosomes and RNA sequences. They tend to have the ability to produce methane.