title: Nitrogen transformations in stratified aquatic microbial ecosystems.
abstract: New analytical methods such as advanced molecular techniques and microsensors have resulted in new insights about how nitrogen transformations in stratified microbial systems such as sediments and biofilms are regulated at a microm-mm scale. A large and ever-expanding knowledge base about nitrogen fixation, nitrification, denitrification, and dissimilatory reduction of nitrate to ammonium, and about the microorganisms performing the processes, has been produced by use of these techniques. During the last decade the discovery of anammmox bacteria and migrating, nitrate accumulating bacteria performing dissimilatory reduction of nitrate to ammonium have given new dimensions to the understanding of nitrogen cycling in nature, and the occurrence of these organisms and processes in stratified microbial communities will be described in detail.
authors.affiliation: Institute of Biological Sciences, Microbiology, University of Aarhus, bd. 540, DK-8000, Aarhus C, Denmark. Revsbech@biology.au.dk
authors.forename: Niels Peter
authors.initials: NP
authors.lastname: Revsbech
authors.forename: Nils
authors.initials: N
authors.lastname: Risgaard-Petersen
authors.forename: Andreas
authors.initials: A
authors.lastname: Schramm
authors.forename: Lars Peter
authors.initials: LP
authors.lastname: Nielsen
mesh_terms: D000332:Aerobiosis; D000693:Anaerobiosis; D001419:Bacteria / Q000235:genetics / Q000378:metabolism*; D017753:Ecosystem; D009584:Nitrogen / Q000378:metabolism*; D009586:Nitrogen Fixation; D010084:Oxidation-Reduction; D000644:Quaternary Ammonium Compounds / Q000378:metabolism; D012623:Seawater / Q000382:microbiology*; D014871:Water Microbiology
chemical_list: D000644:Quaternary Ammonium Compounds; D009584:Nitrogen