title: Bacterial communities potentially involved in iron-cycling in Baltic Sea and North Sea sediments revealed by pyrosequencing.
abstract: To gain insight into the bacterial communities involved in iron-(Fe) cycling under marine conditions, we analysed sediments with Fe-contents (0.5-1.5 wt %) from the suboxic zone at a marine site in the Skagerrak (SK) and a brackish site in the Bothnian Bay (BB) using 16S rRNA gene pyrosequencing. Several bacterial families, including Desulfobulbaceae, Desulfuromonadaceae and Pelobacteraceae and genera, includingDesulfobacterandGeobacter, known to reduce Fe were detected and showed highest abundance near the Fe(III)/Fe(II) redox boundary. Additional genera with microorganisms capable of coupling fermentation to Fe-reduction, includingClostridiumandBacillus, were observed. Also, the Fe-oxidizing families Mariprofundaceae and Gallionellaceae occurred at the SK and BB sites, respectively, supporting Fe-cycling. In contrast, the sulphate (SO4 (2-)) reducing bacteriaDesulfococcusandDesulfobacteriumwere more abundant at greater depths concurring with a decrease in Fe-reducing activity. The communities revealed by pyrosequencing, thus, match the redox stratification indicated by the geochemistry, with the known Fe-reducers coinciding with the zone of Fe-reduction. Not the intensely studied model organisms, such asGeobacterspp., but rather versatile microorganisms, including sulphate reducers and possibly unknown groups appear to be important for Fe-reduction in these marine suboxic sediments.
authors.affiliation: Microbial Ecophysiology, University of Bremen, D-28359 Bremen, Germany creyes6@gmail.com.
authors.forename: Carolina
authors.initials: C
authors.lastname: Reyes
authors.affiliation: Leibniz Institute for Baltic Sea Research (IOW), Geochemistry and Isotope Biogeochemistry Group, D-18119 Warnemünde, Germany.
authors.forename: Olaf
authors.initials: O
authors.lastname: Dellwig
authors.affiliation: Nordic Center for Earth Evolution, University of Southern Denmark, 5230 Odense, Denmark.
authors.forename: Kirstin
authors.initials: K
authors.lastname: Dähnke
authors.affiliation: Department of Isotope Biogeochemistry, Helmholtz Center for Environmental Research (UFZ), 04318 Leipzig, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Gehre
authors.affiliation: Research Group for Marine Geochemistry, University of Oldenburg, D-26111 Oldenburg, Germany.
authors.forename: Beatriz E
authors.initials: BE
authors.lastname: Noriega-Ortega
authors.affiliation: Leibniz Institute for Baltic Sea Research (IOW), Geochemistry and Isotope Biogeochemistry Group, D-18119 Warnemünde, Germany.
authors.forename: Michael E
authors.initials: ME
authors.lastname: Böttcher
authors.affiliation: Department of Geodynamics and Sedimentology, University of Vienna, 1090 Vienna, Austria.
authors.forename: Patrick
authors.initials: P
authors.lastname: Meister
authors.affiliation: Microbial Ecophysiology, University of Bremen, D-28359 Bremen, Germany.
authors.forename: Michael W
authors.initials: MW
authors.lastname: Friedrich
mesh_terms: D001407:Bacillus / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D003013:Clostridium / Q000235:genetics* / Q000378:metabolism; D004269:DNA, Bacterial / Q000235:genetics; D020564:Deltaproteobacteria / Q000235:genetics* / Q000378:metabolism; D005290:Ferric Compounds / Q000378:metabolism*; D019015:Geologic Sediments / Q000382:microbiology*; D007501:Iron / Q000378:metabolism*; D009659:North Sea; D010084:Oxidation-Reduction; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D013431:Sulfates / Q000378:metabolism
chemical_list: D004269:DNA, Bacterial; D005290:Ferric Compounds; D012336:RNA, Ribosomal, 16S; D013431:Sulfates; D007501:Iron
keywords: iron oxidation; iron reduction; marine microbial ecology; marine sediments; microbial communities; next-generation 16S rRNA gene amplicon sequencing