title: A new phylum of Archaea represented by a nanosized hyperthermophilic symbiont.
abstract: According to small subunit ribosomal RNA (ss rRNA) sequence comparisons all known Archaea belong to the phyla Crenarchaeota, Euryarchaeota, and--indicated only by environmental DNA sequences--to the 'Korarchaeota'. Here we report the cultivation of a new nanosized hyperthermophilic archaeon from a submarine hot vent. This archaeon cannot be attached to one of these groups and therefore must represent an unknown phylum which we name 'Nanoarchaeota' and species, which we name 'Nanoarchaeum equitans'. Cells of 'N. equitans' are spherical, and only about 400 nm in diameter. They grow attached to the surface of a specific archaeal host, a new member of the genus Ignicoccus. The distribution of the 'Nanoarchaeota' is so far unknown. Owing to their unusual ss rRNA sequence, members remained undetectable by commonly used ecological studies based on the polymerase chain reaction. 'N. equitans' harbours the smallest archaeal genome; it is only 0.5 megabases in size. This organism will provide insight into the evolution of thermophily, of tiny genomes and of interspecies communication.
authors: Lehrstuhl für Mikrobiologie und Archaeenzentrum, Universität Regensburg, Universitätsstrasse 31, D-93053 Regensburg, Germany.
authors: Harald
authors: H
authors: Huber
authors: Michael J
authors: MJ
authors: Hohn
authors: Reinhard
authors: R
authors: Rachel
authors: Tanja
authors: T
authors: Fuchs
authors: Verena C
authors: VC
authors: Wimmer
authors: Karl O
authors: KO
authors: Stetter
mesh_terms: D001105:Archaea / Q000145:classification* / Q000235:genetics / Q000502:physiology* / Q000648:ultrastructure; D001483:Base Sequence; D005075:Biological Evolution; D015139:Blotting, Southern; D020745:Genome, Archaeal; D006358:Hot Temperature; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D019642:RNA, Archaeal / Q000737:chemistry / Q000235:genetics; D012335:RNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D013559:Symbiosis; D009626:Terminology as Topic
chemical_list: D019642:RNA, Archaeal; D012335:RNA, Ribosomal