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Bacterial dominance in subseafloor sediments characterized by methane hydrates

May 27, 2015

The degradation of organic carbon in subseafloor sediments on continental margins contributes to the largest reservoir of methane on Earth. Sediments in the Andaman Sea are composed of ~ 1% marine-derived organic carbon and biogenic methane is present. Our objective was to determine microbial abundance and diversity in sediments that transition the gas hydrate occurrence zone (GHOZ) in the Andaman Sea. Microscopic cell enumeration revealed that most sediment layers harbored relatively low microbial abundance (103–105 cells cm−3). Archaea were never detected despite the use of both DNA- and lipid-based methods. Statistical analysis of terminal restriction fragment length polymorphisms revealed distinct microbial communities from above, within, and below the GHOZ, and GHOZ samples were correlated with a decrease in organic carbon. Primer-tagged pyrosequences of bacterial 16S rRNA genes showed that members of the phylum Firmicutes are predominant in all zones. Compared with other seafloor settings that contain biogenic methane, this deep subseafloor habitat has a unique microbial community and the low cell abundance detected can help to refine global subseafloor microbial abundance.

Publication Year 2015
Title Bacterial dominance in subseafloor sediments characterized by methane hydrates
DOI 10.1111/j.1574-6941.2012.01311.x
Authors Brandon R. Briggs, Fumio Inagaki, Yuki Morono, Taiki Futagami, Carme Huguet, Antoni Rosell-Mele, T.D. Lorenson, Frederick S. Colwell
Publication Type Article
Publication Subtype Journal Article
Series Title FEMS Microbiology Ecology
Index ID 70148294
Record Source USGS Publications Warehouse
USGS Organization Pacific Coastal and Marine Science Center