Analysis of the first genome fragment from the marine sponge-associated, novel candidate phylum Poribacteria by environmental genomics

Authors

  • Lars Fieseler,

    1. Zentrum für Infektionsforschung, Universität Würzburg, Röntgenring 11, D-97070 Würzburg, Germany.
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  • Achim Quaiser,

    1. Institut für Mikrobiologie und Genetik, Darmstadt University of Technology, Schnittspahnstr. 10, D-64287 Darmstadt, Germany.
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    • Present addresses: Institut de Génétique et Microbiologie, Bâtiment 409, Université Paris-Sud, 91405 Orsay Cedex, France;

  • Christa Schleper,

    1. Institut für Mikrobiologie und Genetik, Darmstadt University of Technology, Schnittspahnstr. 10, D-64287 Darmstadt, Germany.
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    • Department of Biology, University of Bergen, Jahnebakken 5, Box 7800, N-5020 Bergen, Norway.

  • Ute Hentschel

    Corresponding author
    1. Zentrum für Infektionsforschung, Universität Würzburg, Röntgenring 11, D-97070 Würzburg, Germany.
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*E-mail ute.hentschel@mail.uni-wuerzburg.de; Tel. (+49) 931 312581; Fax (+49) 931 312578.

Summary

The novel candidate phylum Poribacteria is specifically associated with several marine demosponge genera. Because no representatives of Poribacteria have been cultivated, an environmental genomic approach was used to gain insights into genomic properties and possibly physiological/functional features of this elusive candidate division. In a large-insert library harbouring an estimated 1.1 Gb of microbial community DNA from Aplysina aerophoba, a Poribacteria-positive 16S rRNA gene locus was identified. Sequencing and sequence annotation of the 39 kb size insert revealed 27 open reading frames (ORFs) and two genes for stable RNAs. The fragment exhibited an overall G+C content of 50.5% and a coding density of 86.1%. The 16S rRNA gene was unlinked from a conventional rrn operon. Its flanking regions did not show any synteny to other 16S rRNA encoding loci from microorganisms with unlinked rrn operons. Two of the predicted hypothetical proteins were highly similar to homologues from Rhodopirellula baltica. Furthermore, a novel kind of molybdenum containing oxidoreductase was predicted as well as a series of eight ORFs encoding for unusual transporters, channel or pore forming proteins. This environmental genomics approach provides, for the first time, genomic and, by inference, functional information on the so far uncultivated, sponge-associated candidate division Poribacteria.

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