title: Archaeal communities associated with shallow to deep subseafloor sediments of the New Caledonia Basin.
abstract: 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 approximately 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.
authors.affiliation: Laboratoire de Microbiologie des Environnements Extrêmes, UMR 6197, Université de Bretagne Occidentale, Ifremer, France. rousseleg@cardiff.ac.uk
authors.forename: Erwan G
authors.initials: EG
authors.lastname: Roussel
authors.forename: Anne-Laure
authors.initials: AL
authors.lastname: Sauvadet
authors.forename: Carine
authors.initials: C
authors.lastname: Chaduteau
authors.forename: Yves
authors.initials: Y
authors.lastname: Fouquet
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Charlou
authors.forename: Daniel
authors.initials: D
authors.lastname: Prieur
authors.forename: Marie-Anne
authors.initials: MA
authors.lastname: Cambon Bonavita
mesh_terms: D001105:Archaea / Q000145:classification* / Q000235:genetics; D001483:Base Sequence; D044822:Biodiversity; D018533:Biomass; D004586:Electrophoresis / Q000379:methods; D005843:Geography; D019015:Geologic Sediments / Q000737:chemistry / Q000382:microbiology*; D008969:Molecular Sequence Data; D009510:New Caledonia; D009792:Oceans and Seas; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism; D010140:Pacific Ocean; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000032:analysis; D012623:Seawater / Q000737:chemistry / Q000382:microbiology
chemical_list: D012336:RNA, Ribosomal, 16S; D010088:Oxidoreductases; C045582:ammonia monooxygenase