title: Sulfur oxidizers dominate carbon fixation at a biogeochemical hot spot in the dark ocean.
abstract: Bacteria and archaea in the dark ocean (>200 m) comprise 0.3-1.3 billion tons of actively cycled marine carbon. Many of these microorganisms have the genetic potential to fix inorganic carbon (autotrophs) or assimilate single-carbon compounds (methylotrophs). We identified the functions of autotrophic and methylotrophic microorganisms in a vent plume at Axial Seamount, where hydrothermal activity provides a biogeochemical hot spot for carbon fixation in the dark ocean. Free-living members of the SUP05/Arctic96BD-19 clade of marine gamma-proteobacterial sulfur oxidizers (GSOs) are distributed throughout the northeastern Pacific Ocean and dominated hydrothermal plume waters at Axial Seamount. Marine GSOs expressed proteins for sulfur oxidation (adenosine phosphosulfate reductase, sox (sulfur oxidizing system), dissimilatory sulfite reductase and ATP sulfurylase), carbon fixation (ribulose-1,5-bisphosphate carboxylase oxygenase (RuBisCO)), aerobic respiration (cytochrome c oxidase) and nitrogen regulation (PII). Methylotrophs and iron oxidizers were also active in plume waters and expressed key proteins for methane oxidation and inorganic carbon fixation (particulate methane monooxygenase/methanol dehydrogenase and RuBisCO, respectively). Proteomic data suggest that free-living sulfur oxidizers and methylotrophs are among the dominant primary producers in vent plume waters in the northeastern Pacific Ocean.
authors.affiliation: Department of Civil and Environmental Engineering, University of Iowa, Iowa City, IA, USA.
authors.forename: Timothy E
authors.initials: TE
authors.lastname: Mattes
authors.forename: Brook L
authors.initials: BL
authors.lastname: Nunn
authors.forename: Katharine T
authors.initials: KT
authors.lastname: Marshall
authors.forename: Giora
authors.initials: G
authors.lastname: Proskurowski
authors.forename: Deborah S
authors.initials: DS
authors.lastname: Kelley
authors.forename: Orest E
authors.initials: OE
authors.lastname: Kawka
authors.forename: David R
authors.initials: DR
authors.lastname: Goodlett
authors.forename: Dennis A
authors.initials: DA
authors.lastname: Hansell
authors.forename: Robert M
authors.initials: RM
authors.lastname: Morris
mesh_terms: D044822:Biodiversity; D052837:Chemoautotrophic Growth; D020563:Gammaproteobacteria / Q000145:classification / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D060086:Hydrothermal Vents / Q000382:microbiology*; D000432:Methanol / Q000378:metabolism; D010084:Oxidation-Reduction; D010140:Pacific Ocean; D010802:Phylogeny; D040901:Proteomics; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012623:Seawater / Q000382:microbiology*
chemical_list: D012336:RNA, Ribosomal, 16S; D000432:Methanol