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

• Published in: Environmental Microbiology
• Main Authors: Roussel, Erwan, Sauvadet, Anne-laure, Chaduteau, Carine, Fouquet, Yves, Charlou, Jean-luc, Prieur, Daniel, Cambon, Marie-anne
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley / Blackwell 2009
• Subjects: marine subsurface sediments; sea floor biosphere; gradient gel electrophoresis; microbial communities; molecular diversity; anaerobic oxidation; sequence alignment; phylogenetic trees; extracellular DNA; methane hydrate; Methane hydrate
• Online Access: https://archimer.ifremer.fr/doc/2009/publication-6801.pdf; https://doi.org/10.1111/j.1462-2920.2009.01976.x; https://archimer.ifremer.fr/doc/00000/6801/

P>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 similar to 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.