Ignicoccus

From Wikipedia, the free encyclopedia

Ignicoccus

Kingdom:	Archaea
Phylum:	Crenarchaeota
Class:	Thermoprotei
Order:	Desulfurococcales
Family:	Desulfurococcaceae
Genus:	Ignicoccus

Species

Ignicoccus islandicus

Ignicoccus pacificus

Ignicoccus sp. KIN4I

Synonyms

Ignicoccus Huber et al. 2000

Ignicoccus is a genus of Archaea living in marine hydrothermal vents. They were discovered in Kolbeinsey Ridge north of Iceland and in the Pacific Ocean (at 9 degrees N, 104 degrees W) in 2000 (Huber et al., 2000).

1 Systematics
2 Cell structure
3 Physiology
4 References

[edit] Systematics

According to the comparisons of 16S rRNA genes, Ignicoccus represents a new, deeply branching lineage within the family of the Desulfurococcaceae (Huber et al., 2002). Three species are known, Ignicoccus islandicus, Ignicoccus pacificus and Ignicoccus sp. strain KIN4I (as yet unnamed).

[edit] Cell structure

The archebacteria of the genus Ignicoccus have tiny coccoid cells with a diameter of about 2 µm, that exhibit a smooth surface, an outer membrane and no S-layer.

They have a previously unknown cell envelope structure - a cytoplasmic membrane, a periplasmic space (with a variable width of 20 to 400 nm, containing membrane-bound vesicles), and an outer membrane (approximately 10 nm wide, resembling the outer membrane of gram-negative bacteria). The latter contains numerous tightly, irregularly packed single particles (about 8 nm in diameter) and pores with a diameter of 24 nm, surrounded by tiny particles, arranged in a ring (with a diameter of 130 nm) and clusters of up to eight particles (each particle 12 nm in diameter) (Rachel et al. 2002).

[edit] Physiology

Ignicocci live in a temperature range of 70-98 °C (optimum around 90 °C). They gain energy by reduction of elemental sulfur to hydrogen sulfide using molecular hydrogen as the electron donor (Huber et al., 2002). A unique symbiosis with (or parasitism of) nanoarchaea has also been reported (Huber et al., 2002).

[edit] References

Huber H, Burggraf S, Mayer T, Wyschkony I, Rachel R, Stetter KO Ignicoccus gen. nov., a novel genus of hyperthermophilic, chemolithoautotrophic Archaea, represented by two new species, Ignicoccus islandicus sp nov and Ignicoccus pacificus sp nov. and Ignicoccus pacificus sp. nov, Int J Syst Evol Microbiol. 2000 Nov;50 Pt 6:2093-100
Rachel, R, Wyschkony, I, Riehl, S and Huber, H. The ultrastructure of Ignicoccus: Evidence for a novel outer membrane and for intracellular vesicle budding in an archaeon Archaea, 1:9–18 2002
Huber H, Hohn MJ, Rachel R, Fuchs T, Wimmer VC, Stetter KO. A new phylum of Archaea represented by a nanosized hyperthermophilic symbiont, Nature, 417(6884):27-8, 2002