Bacterial Kingdoms - Eubacteria and Archaebacteria

Archaebacteria

This group probably represents the first living cells.

The methanogens are "methane-makers."

They live in swamps, mud, sewage, and animal guts.
They make ATP anaerobically (without the need for oxygen) by converting carbon dioxide and hydrogen to methane.

The extreme halophiles are "salt-lovers."

These species can tolerate high salt environments such as brackish ponds, salt lakes, volcanic vents on the seafloor, and the like.
Most are heterotrophic aerobes (use oxygen), but some can switch to a special photosynthesis, using bacteriorhodopsin, to produce ATP.

The extreme thermophiles are "heat-lovers."

These bacteria live in hot springs and other very hot places such as the thermal vents of the sea floor where temperatures exceed 110^o C.
They use hydrogen sulfide for ATP formation.

Photoautotrophs

Cyanobacteria are photosynthetic.
Anabaena, by means of heterocysts, can fix nitrogen.
Green and purple bacteria use hydrogen sulfide and hydrogen gas as a source of electrons for photosynthesis.

Chemoautotrophs

Among the most important are the nitrifying bacteria that participate in nitrogen cycling.
They ammonia for generating ATP.

Chemoheterotrophs

Pseudomonads are major decomposers in the soil.
Actinomycetes produce antibiotics.
Lactobacillus is used in dairy product conversions.
E. coli makes vitamin K in the human gut.
Rhizobium fixes nitrogen on the roots of legumes.
Some strains of E. coli can cause serious diarrhea.
Some form resistant endospores that can survive harsh environmental conditions, for example Clostridium botulinum (botulism) or Anthrax. The figure illustrates endospore formation (reading from left to right). Endospores are a method of survival. The spore is formed within the cell membrane (an endospore) and allows the bacteria to wait out deteriorating environmental conditions.
Borrelia burgdorferi a spirochete bacteria is transmitted by ticks to humans where it causes Lyme disease.