Bacteria Genomes - AQUIFEX AEOLICUS

Aquifex aeolicusare are nonsporeforming, Gram-negative , generally rod-shaped organisms. They are about 2.0-6.0 micrometers in length and have a diameter of 0.4-0.5 micrometers.

Although this organism is able to grow at a remarkable 96 C, only a few specific indications of heat-resistance are evident from the genome. It can grow on hydrogen, oxygen, carbon dioxide, and mineral salts.

Aquifex aeolicus is thought to be one of the earliest bacteria to diverge from the evolutionary tree of the eubacteria; and further analysis may throw light on the question of where the extreme thermophiles belong on the phylogenetic tree. Perhaps this heat tolerance is a legacy from the earliest of bacterial forms or it could have evolved much later to fill a vacant niche in the environment.

Aquifex aeolicus functions as a chemolithoautotroph (an organism which uses an inorganic carbon source for biosynthesis and an inorganic chemical energy source) and is encoded within a genome that is only one-third the size of the E. coli genome. Metabolic flexibility seems to be reduced as a result of the limited genome size. The use of oxygen (albeit at very low concentrations) as an electron acceptor is allowed by the presence of a complex respiratory apparatus.

References:

http://www.nature.com/genomics/papers/a_aeolicus.html
Nature 392: 353-358 (1998)