Subsurface microbiology and biogeochemistry of a deep, cold-water carbonate mound from the Porcupine Seabight (IODP Expedition 307).
The Porcupine Seabight Challenger Mound is the first carbonate mound to be drilled (approximately 270 m) and analyzed in detail microbiologically and biogeochemically. Two mound sites and a non-mound Reference site were analyzed with a range of molecular techniques [catalyzed reporter deposition-fluorescence in situ hybridization (CARD-FISH), quantitative PCR (16S rRNA and functional genes, dsrA and mcrA), and 16S rRNA gene PCR-DGGE] to assess prokaryotic diversity, and this was compared with the distribution of total and culturable cell counts, radiotracer activity measurements and geochemistry. There was a significant and active prokaryotic community both within and beneath the carbonate mound. Although total cell numbers at certain depths were lower than the global average for other subseafloor sediments and prokaryotic activities were relatively low (iron and sulfate reduction, acetate oxidation, methanogenesis) they were significantly enhanced compared with the Reference site. In addition, there was some stimulation of prokaryotic activity in the deepest sediments (Miocene, > 10 Ma) including potential for anaerobic oxidation of methane activity below the mound base. Both Bacteria and Archaea were present, with neither dominant, and these were related to sequences commonly found in other subseafloor sediments. With an estimate of some 1600 mounds in the Porcupine Basin alone, carbonate mounds may represent a significant prokaryotic subseafloor habitat.
Webster
Gordon
G
Cardiff School of Biosciences, Cardiff University, Park Place, Cardiff, Wales, UK.
Blazejak
Anna
A
Cragg
Barry A
BA
Schippers
Axel
A
Sass
Henrik
H
Rinna
Joachim
J
Tang
Xiaohong
X
Mathes
Falko
F
Ferdelman
Timothy G
TG
Fry
John C
JC
Weightman
Andrew J
AJ
Parkes
R John
RJ
D001105:Archaea / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D001419:Bacteria / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D044822:Biodiversity; D019641:DNA, Archaeal / Q000737:chemistry / Q000235:genetics; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D020459:Genes, rRNA; D017404:In Situ Hybridization, Fluorescence; D008969:Molecular Sequence Data; D009792:Oceans and Seas; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D012689:Sequence Homology, Nucleic Acid; D012987:Soil / Q000032:analysis*; D012988:Soil Microbiology
D019641:DNA, Archaeal; D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D012336:RNA, Ribosomal, 16S; D012987:Soil