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Letters to Nature

Nature 417, 63-67 (2 May 2002) | doi:10.1038/417063a; Received 7 November 2001; Accepted 29 January 2002

A new phylum of Archaea represented by a nanosized hyperthermophilic symbiont

Harald Huber1, Michael J. Hohn1, Reinhard Rachel1, Tanja Fuchs1,2, Verena C. Wimmer3 & Karl O. Stetter1

  1. Lehrstuhl für Mikrobiologie und Archaeenzentrum, Universität Regensburg, Universitätsstrasse 31, D-93053 Regensburg, Germany
  2. Max Planck Institute for Medical Research, Department of Cell Physiology, Jahnstrasse 29, 69120 Heidelberg, Germany
  3. Present address: AstraZeneca GmbH, Tinsdaler Weg 183, D-22876 Wedel, Germany.

Correspondence to: Karl O. Stetter1 Correspondence and requests for material should be addressed to K.O.S. (e-mail: Email: karl.stetter@biologie.uni-regensburg.de). The 16S rRNA (ss rRNA) sequences for 'Nanoarchaeum equitans' and Ignicoccus sp. were deposited at GenBank under accession numbers AJ318041 and AJ318042, respectively.

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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'1, 2. 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 Ignicoccus3. 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 reaction4. '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.

  1. Lehrstuhl für Mikrobiologie und Archaeenzentrum, Universität Regensburg, Universitätsstrasse 31, D-93053 Regensburg, Germany
  2. Max Planck Institute for Medical Research, Department of Cell Physiology, Jahnstrasse 29, 69120 Heidelberg, Germany
  3. Present address: AstraZeneca GmbH, Tinsdaler Weg 183, D-22876 Wedel, Germany.

Correspondence to: Karl O. Stetter1 Correspondence and requests for material should be addressed to K.O.S. (e-mail: Email: karl.stetter@biologie.uni-regensburg.de). The 16S rRNA (ss rRNA) sequences for 'Nanoarchaeum equitans' and Ignicoccus sp. were deposited at GenBank under accession numbers AJ318041 and AJ318042, respectively.