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A new phylum of Archaea represented by a nanosized hyperthermophilic symbiont

Nature volume 417, pages 6367 (02 May 2002) | Download Citation



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.

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We thank W. Ludwig and D. Prangishvili for stimulating discussions, S. Diller, S. Leptihn, M. Brandl, I. Wyschkony and P. Hummel for technical support, and B. Hedlund for critically reading the manuscript. We are grateful to the cruise leader P. Stoffers, the crew of RV Poseidon and the submersible Jago team for support during sampling, and the Icelandic government for a research permit. This study was supported by the Deutsche Forschungsgemeinschaft and the Fonds der Chemischen Industrie.

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Author notes

    • Tanja Fuchs

    Present address: AstraZeneca GmbH, Tinsdaler Weg 183, D-22876 Wedel, Germany.


  1. *Lehrstuhl für Mikrobiologie und Archaeenzentrum, Universität Regensburg, Universitätsstrasse 31, D-93053 Regensburg, Germany

    • Harald Huber
    • , Michael J. Hohn
    • , Reinhard Rachel
    • , Tanja Fuchs
    •  & Karl O. Stetter
  2. ‡Max Planck Institute for Medical Research, Department of Cell Physiology, Jahnstrasse 29, 69120 Heidelberg, Germany

    • Verena C. Wimmer


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The authors declare that they have no competing financial interests

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Correspondence to Karl O. Stetter.

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