title: Nitrogen Metabolism Genes from Temperate Marine Sediments.
abstract: In this study, we analysed metagenomes along with biogeochemical profiles from Skagerrak (SK) and Bothnian Bay (BB) sediments, to trace the prevailing nitrogen pathways. NO3-was present in the top 5 cm below the sediment-water interface at both sites. NH4+increased with depth below 5 cm where it overlapped with the NO3-zone. Steady-state modelling of NO3-and NH4+porewater profiles indicates zones of net nitrogen species transformations. Bacterial protease and hydratase genes appeared to make up the bulk of total ammonification genes. Genes involved in ammonia oxidation (amo, hao), denitrification (nir, nor), dissimilatory NO3-reduction to NH4+(nfr and otr) and in both of the latter two pathways (nar, nap) were also present. Results show ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) are similarly abundant in both sediments. Also, denitrification genes appeared more abundant than DNRA genes. 16S rRNA gene analysis showed that the relative abundance of the nitrifying group Nitrosopumilales and other groups involved in nitrification and denitrification (Nitrobacter, Nitrosomonas, Nitrospira, Nitrosococcus and Nitrosomonas) appeared less abundant in SK sediments compared to BB sediments. Beggiatoa and Thiothrix 16S rRNA genes were also present, suggesting chemolithoautotrophic NO3-reduction to NO2-or NH4+as a possible pathway. Our results show the metabolic potential for ammonification, nitrification, DNRA and denitrification activities in North Sea and Baltic Sea sediments.
authors.affiliation: Microbial Ecophysiology, University of Bremen, Leobener Strasse, D-28359, Bremen, Germany. creyes6@gmail.com.|Department of Environmental Geosciences, University of Vienna, Althanstrasse 14, 1090, Vienna, Austria. creyes6@gmail.com.
authors.forename: Carolina
authors.initials: C
authors.lastname: Reyes
authors.affiliation: Department of Genomic and Applied Microbiology, University of Göttingen, Grisebachstrasse 8, D-37077, Göttingen, Germany.
authors.forename: Dominik
authors.initials: D
authors.lastname: Schneider
authors.affiliation: Geochemistry and Stable Isotope Biogeochemistry Group, Leibniz Institute for Baltic Sea Research (IOW), Seestrasse 15, D-18119, Warnemünde, Germany.
authors.forename: Marko
authors.initials: M
authors.lastname: Lipka
authors.affiliation: Department of Genomic and Applied Microbiology, University of Göttingen, Grisebachstrasse 8, D-37077, Göttingen, Germany.
authors.forename: Andrea
authors.initials: A
authors.lastname: Thürmer
authors.affiliation: Geochemistry and Stable Isotope Biogeochemistry Group, Leibniz Institute for Baltic Sea Research (IOW), Seestrasse 15, D-18119, Warnemünde, Germany.
authors.forename: Michael E
authors.initials: ME
authors.lastname: Böttcher
authors.affiliation: Microbial Ecophysiology, University of Bremen, Leobener Strasse, D-28359, Bremen, Germany.
authors.forename: Michael W
authors.initials: MW
authors.lastname: Friedrich
mesh_terms: D001105:Archaea / Q000235:genetics; D001419:Bacteria / Q000235:genetics; D058440:Denitrification / Q000235:genetics; D019015:Geologic Sediments / Q000737:chemistry / Q000382:microbiology*; D054892:Metagenome; D058465:Nitrification / Q000235:genetics; D017672:Nitrogen Compounds / Q000378:metabolism*; D009792:Oceans and Seas; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012623:Seawater / Q000737:chemistry
chemical_list: D017672:Nitrogen Compounds; D012336:RNA, Ribosomal, 16S
keywords: Marine; Metagenome; Nitrogen; Sediments