title: Subseafloor microbial communities associated with rapid turbidite deposition in the Gulf of Mexico continental slope (IODP Expedition 308).
abstract: The subseafloor microbial communities in the turbidite depositional basins Brazos-Trinity Basin IV (BT Basin) and the Mars-Ursa Basin (Ursa Basin) on the Gulf of Mexico continental slope (IODP holes U1319A, U1320A, U1322B and U1324B) were investigated by PCR-dependent molecular analyses targeted to the small subunit (SSU) rRNA genes, dsrA and mcrA, and hydrogenase activity measurements. Biomass at both basins was very low, with the maximum cell or the SSU rRNA gene copy number <1 x 10(7) cells mL(-1) or copies g(-1) sediments, respectively. Hydrogenase activity correlated with biomass estimated by SSU rRNA gene copy number when all data sets were combined. We detected differences in the SSU rRNA gene community structures and SSU rRNA gene copy numbers between the basin-fill and basement sediments in the BT Basin. Examination of microbial communities and hydrogenase activity in the context of geochemical and geophysical parameters and sediment depositional environments revealed that differences in microbial community composition between the basin-fill and basement sediments in the BT Basin were associated with sedimentation regimes tied to the sea-level change. This may also explain the distributions of relatively similar archaeal communities in the Ursa Basin sediments and basement sediments in the BT Basin.
authors: Subsurface Geobiology and Advanced Research (SUGAR) Project, Extremobiosphere Research Program, Institute of Biogeosciences, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Yokosuka 237-0061, Japan. takuron@jamstec.go.jp
authors: Takuro
authors: T
authors: Nunoura
authors: Bruno
authors: B
authors: Soffientino
authors: Anna
authors: A
authors: Blazejak
authors: Jungo
authors: J
authors: Kakuta
authors: Hanako
authors: H
authors: Oida
authors: Axel
authors: A
authors: Schippers
authors: Ken
authors: K
authors: Takai
mesh_terms: D001105:Archaea / Q000145:classification / Q000201:enzymology / Q000235:genetics*; D018533:Biomass; D019641:DNA, Archaeal / Q000235:genetics; D017753:Ecosystem; D019766:Genes, Archaeal; D020459:Genes, rRNA; D019015:Geologic Sediments / Q000382:microbiology*; D006864:Hydrogenase / Q000378:metabolism; D008969:Molecular Sequence Data; D012150:Polymorphism, Restriction Fragment Length; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D014871:Water Microbiology
chemical_list: D019641:DNA, Archaeal; D012336:RNA, Ribosomal, 16S; D006864:Hydrogenase