Archaebacteria
Archea (which means ancient) are found in the most extreme environments.
These bacteria include methanogen (produce methane), thermoacidophiles (live in hot, acidic water) and 
halophiles (live in high salt conditions)


Examples :

Methanobrevibacter smithii
Methanogen bacteria

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Halobacterium salinarum
Halophile bacteria

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Thermococcus litoralis
Thermoacidophile bacteria




Eubacteria
Eubacteria and cyanobacteria are the two major form of life in this domain.
It is the most common bacteria and is also the most commonly referred to.


Examples :

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E.coli bacteria

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Salmonella enterica bacteria

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Streptococcus pneumoniae bacteria

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