Diversity and abundance of aerobic and anaerobic methane oxidizers at the Haakon Mosby Mud Volcano, Barents Sea.

• Published in: Applied and Environmental Microbiology
• Main Authors: Lösekann, Tina, Knittel, Katrin, Nadalig, Thierry, Fuchs, Bernhard, Niemann, Helge, Boetius, Antje, Amann, Rudolf
• Other Authors: Max Planck Institute for Marine Microbiology, Max-Planck-Gesellschaft, Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Génétique moléculaire, génomique, microbiologie (GMGM), Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'InfoRmatique en Image et Systèmes d'information (LIRIS), Université Lumière - Lyon 2 (UL2)-École Centrale de Lyon (ECL), Université de Lyon-Université de Lyon-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Institut de biologie et chimie des protéines Lyon (IBCP), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS), Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung (AWI), Department of Bentho-pelagic processes, Jacobs University Bremen, Laboratoire Environnement Profond (LEP), Etudes des Ecosystèmes Profonds (EEP), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2007
• Subjects: MESH: Aerobiosis; MESH: Anaerobiosis; MESH: Phylogeny; MESH: Piscirickettsiaceae; MESH: Archaea; MESH: Protein Subunits; MESH: RNA; Ribosomal; 16S; MESH: Seawater; MESH: Bacteria; MESH: Base Sequence; MESH: Beggiatoa; MESH: DNA; Archaeal; MESH: Geologic Sediments; Bacterial; MESH: Deltaproteobacteria; MESH: In Situ Hybridization; Fluorescence; MESH: Methane; MESH: Methylococcaceae; MESH: Microscopy; MESH: Molecular Sequence Data; MESH: Oxidation-Reduction; MESH: Oxidoreductases; [SDV.BBM]Life Sciences [q-bio]/Biochemistry; Molecular Biology; Barents Sea
• Online Access: https://hal.science/hal-00390579; https://doi.org/10.1128/AEM.00016-07

International audience Submarine mud volcanoes are formed by expulsions of mud, fluids, and gases from deeply buried subsurface sources. They are highly reduced benthic habitats and often associated with intensive methane seepage. In this study, the microbial diversity and community structure in methane-rich sediments of the Haakon Mosby Mud Volcano (HMMV) were investigated by comparative sequence analysis of 16S rRNA genes and fluorescence in situ hybridization. In the active volcano center, which has a diameter of about 500 m, the main methane-consuming process was bacterial aerobic oxidation. In this zone, aerobic methanotrophs belonging to three bacterial clades closely affiliated with Methylobacter and Methylophaga species accounted for 56%+/-8% of total cells. In sediments below Beggiatoa mats encircling the center of the HMMV, methanotrophic archaea of the ANME-3 clade dominated the zone of anaerobic methane oxidation. ANME-3 archaea form cell aggregates mostly associated with sulfate-reducing bacteria of the Desulfobulbus (DBB) branch. These ANME-3/DBB aggregates were highly abundant and accounted for up to 94%+/-2% of total microbial biomass at 2 to 3 cm below the surface. ANME-3/DBB aggregates could be further enriched by flow cytometry to identify their phylogenetic relationships. At the outer rim of the mud volcano, the seafloor was colonized by tubeworms (Siboglinidae, formerly known as Pogonophora). Here, both aerobic and anaerobic methane oxidizers were found, however, in lower abundances. The level of microbial diversity at this site was higher than that at the central and Beggiatoa species-covered part of the HMMV. Analysis of methyl-coenzyme M-reductase alpha subunit (mcrA) genes showed a strong dominance of a novel lineage, mcrA group f, which could be assigned to ANME-3 archaea. Our results further support the hypothesis of Niemann et al. (54), that high methane availability and different fluid flow regimens at the HMMV provide distinct niches for aerobic and anaerobic methanotrophs.