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Archaeal communities associated with shallow to deep subseafloor sediments of the New Caledonia Basin

Authors

  • Erwan G. Roussel,

    Corresponding author
    1. Laboratoire de Microbiologie des Environnements Extrêmes, UMR 6197, Université de Bretagne Occidentale, Ifremer, CNRS, Institut Universitaire Européen de la Mer, 29280 Plouzané, France.
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    • Present address: School of Earth and Ocean Sciences, Cardiff University, Main Building, Park Place, Cardiff, Wales, UK.

    • Equal contribution.

  • Anne-Laure Sauvadet,

    1. Laboratoire de Microbiologie des Environnements Extrêmes, UMR 6197, Université de Bretagne Occidentale, Ifremer, CNRS, Institut Universitaire Européen de la Mer, 29280 Plouzané, France.
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    • Equal contribution.

  • Carine Chaduteau,

    1. Département Géosciences Marines, Ifremer, Centre de Brest, 29280 Plouzané, France.
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  • Yves Fouquet,

    1. Département Géosciences Marines, Ifremer, Centre de Brest, 29280 Plouzané, France.
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  • Jean-Luc Charlou,

    1. Département Géosciences Marines, Ifremer, Centre de Brest, 29280 Plouzané, France.
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  • Daniel Prieur,

    1. Laboratoire de Microbiologie des Environnements Extrêmes, UMR 6197, Université de Bretagne Occidentale, Ifremer, CNRS, Institut Universitaire Européen de la Mer, 29280 Plouzané, France.
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  • Marie-Anne Cambon Bonavita

    1. Laboratoire de Microbiologie des Environnements Extrêmes, UMR 6197, Université de Bretagne Occidentale, Ifremer, CNRS, Institut Universitaire Européen de la Mer, 29280 Plouzané, France.
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*E-mail rousseleg@cardiff.ac.uk; Tel. (+44) 29 2087 4488; Fax (+44) 29 2087 4326.

Summary

The distribution of the archaeal communities in deep subseafloor sediments [0–36 m below the seafloor (mbsf)] from the New Caledonia and Fairway Basins was investigated using DNA- and RNA-derived 16S rRNA clone libraries, functional genes and denaturing gradient gel electrophoresis (DGGE). A new method, Co-Migration DGGE (CM-DGGE), was developed to access selectively the active archaeal diversity. Prokaryotic cell abundances at the open-ocean sites were on average ∼3.5 times lower than at a site under terrestrial influence. The sediment surface archaeal community (0–1.5 mbsf) was characterized by active Marine Group 1 (MG-1) Archaea that co-occurred with ammonia monooxygenase gene (amoA) sequences affiliated to a group of uncultured sedimentary Crenarchaeota. However, the anoxic subsurface methane-poor sediments (below 1.5 mbsf) were dominated by less active archaeal communities, such as the Thermoplasmatales, Marine Benthic Group D and other lineages probably involved in the methane cycle (Methanosarcinales, ANME-2 and DSAG/MBG-B). Moreover, the archaeal diversity of some sediment layers was restricted to only one lineage (Uncultured Euryarchaeota, DHVE6, MBG-B, MG-1 and SAGMEG). Sequences forming two clusters within the Thermococcales order were also present in these cold subseafloor sediments, suggesting that these uncultured putative thermophilic archaeal communities might have originated from a different environment. This study shows a transition between surface and subsurface sediment archaeal communities.

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