title: Anaerobic ammonium-oxidizing bacteria in marine environments: widespread occurrence but low diversity.
abstract: Laboratory and field studies have indicated that anaerobic ammonium oxidation (anammox) is an important process in the marine nitrogen cycle. In this study 11 additional anoxic marine sediment and water column samples were studied to substantiate this claim. In a combined approach using the molecular methods, polymerase chain reaction (PCR), qualitative and quantitative fluorescence in situ hybridization (FISH), as well as (15)N stable isotope activity measurements, it was shown that anammox bacteria were present and active in all samples investigated. The anammox activity measured in the sediment samples ranged from 0.08 fmol cell(-1) day(-1) N(2) in the Golfo Dulce (Pacific Ocean, Costa Rica) sediment to 0.98 fmol cell(-1) day(-1) N(2) in the Gullmarsfjorden (North Sea, Sweden) sediment. The percentage of anammox cell of the total population (stained with DAPI) as assessed by quantitative FISH was highest in the Barents Sea (9% +/- 4%) and in most of the samples well over 2%. Fluorescence in situ hybridization and phylogenetic analysis of the PCR products derived from the marine samples indicated the exclusive presence of members of the Candidatus'Scalindua' genus. This study showed the ubiquitous presence of anammox bacteria in anoxic marine ecosystems, supporting previous observations on the importance of anammox for N cycling in marine environments.
authors.affiliation: Department of Microbiology, IWWR, Radboud University Nijmegen, Toernooiveld 1, NL-6525 ED Nijmegen, The Netherlands.
authors.forename: Markus C
authors.initials: MC
authors.lastname: Schmid
authors.forename: Nils
authors.initials: N
authors.lastname: Risgaard-Petersen
authors.forename: Jack
authors.initials: J
authors.lastname: van de Vossenberg
authors.forename: Marcel M M
authors.initials: MM
authors.lastname: Kuypers
authors.forename: Gaute
authors.initials: G
authors.lastname: Lavik
authors.forename: Jan
authors.initials: J
authors.lastname: Petersen
authors.forename: Stefan
authors.initials: S
authors.lastname: Hulth
authors.forename: Bo
authors.initials: B
authors.lastname: Thamdrup
authors.forename: Don
authors.initials: D
authors.lastname: Canfield
authors.forename: Tage
authors.initials: T
authors.lastname: Dalsgaard
authors.forename: Søren
authors.initials: S
authors.lastname: Rysgaard
authors.forename: Mikael K
authors.initials: MK
authors.lastname: Sejr
authors.forename: Marc
authors.initials: M
authors.lastname: Strous
authors.forename: Huub J M Op
authors.initials: HJ
authors.lastname: den Camp
authors.forename: Mike S M
authors.initials: MS
authors.lastname: Jetten
mesh_terms: D000693:Anaerobiosis; D001421:Bacteria, Anaerobic / Q000145:classification / Q000378:metabolism* / Q000502:physiology; D004269:DNA, Bacterial / Q000737:chemistry / Q000302:isolation & purification; D004275:DNA, Ribosomal / Q000737:chemistry / Q000302:isolation & purification; D017404:In Situ Hybridization, Fluorescence; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D000644:Quaternary Ammonium Compounds / Q000378:metabolism*; D012336:RNA, Ribosomal, 16S / Q000032:analysis / Q000235:genetics; D012623:Seawater / Q000737:chemistry*; D017422:Sequence Analysis, DNA
chemical_list: D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D000644:Quaternary Ammonium Compounds; D012336:RNA, Ribosomal, 16S