Bacillus

Bacteria. This domain includes the kingdom of the heterotrophic eubacteria and
includes all human pathogen bacteria. The other kingdoms, for instance that of the
photosynthetic cyanobacteria, are not pathogenic. It is estimated that bacterial species
on Earth number in the hundreds of thousands, of which only about 5500 have
been discovered and described in detail.
Archaea. This domain includes forms that live under extreme environmental conditions,
including thermophilic, hyperthermophilic, halophilic, and methanogenic
microorganisms. The earlier term for the archaea was archaebacteria (ancient bacteria),
and they are indeed a kind of living fossil. Thermophilic archaea thrive mainly
in warm, moist biotopes such as the hot springs at the top of geothermal vents. The
hyperthermophilic archaea, a more recent discovery, live near deep-sea volcanic
plumes at temperatures exceeding 100 8C.
Eucarya. This domain includes all life forms with cells possessing a genuine nucleus.
The plant and animal kingdoms (animales and plantales) are all eukaryotic life
forms. Pathogenic eukaryotic microorganisms include fungal and protozoan species.