title: In situ distribution and activity of nitrifying bacteria in freshwater sediment.
abstract: Nitrification was investigated in a model freshwater sediment by the combined use of microsensors and fluorescence in situ hybridization with rRNA-targeted oligonucleotide probes. In situ nitrification activity was restricted mainly to the upper 2 mm of the sediment and coincided with the maximum abundance of nitrifying bacteria, i.e. 1.5 x 107 cells cm-3 for ammonia-oxidizing Beta-proteobacteria (AOB) and 8.6 x 107 cells cm-3 for Nitrospira-like nitrite-oxidizing bacteria (NOB). Cell numbers of AOB decreased more rapidly with depth than numbers of NOB. For the first time, Nitrospira-like bacteria could be quantified and correlated with in situ nitrite oxidation rates in a sediment. Estimated cell-specific nitrite oxidation rates were 1.2-2.7 fmol NO2- cell-1 h-1.
authors.affiliation: Max Planck Institute for Marine Microbiology, D-28359 Bremen, Germany.
authors.forename: Dörte
authors.initials: D
authors.lastname: Altmann
authors.forename: Peter
authors.initials: P
authors.lastname: Stief
authors.forename: Rudolf
authors.initials: R
authors.lastname: Amann
authors.forename: Dirk
authors.initials: D
authors.lastname: De Beer
authors.forename: Andreas
authors.initials: A
authors.lastname: Schramm
mesh_terms: D001419:Bacteria / Q000145:classification / Q000254:growth & development / Q000378:metabolism*; D020562:Betaproteobacteria / Q000254:growth & development / Q000378:metabolism; D015169:Colony Count, Microbial; D005618:Fresh Water / Q000382:microbiology*; D019015:Geologic Sediments / Q000382:microbiology*; D017404:In Situ Hybridization, Fluorescence; D009573:Nitrites / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism*; D000644:Quaternary Ammonium Compounds / Q000378:metabolism*; D014871:Water Microbiology
chemical_list: D009573:Nitrites; D000644:Quaternary Ammonium Compounds; D010100:Oxygen