title: Competition and coexistence of aerobic ammonium- and nitrite-oxidizing bacteria at low oxygen concentrations.
abstract: In natural and man-made ecosystems nitrifying bacteria experience frequent exposure to oxygen-limited conditions and thus have to compete for oxygen. In several reactor systems (retentostat, chemostat and sequencing batch reactors) it was possible to establish co-cultures of aerobic ammonium- and nitrite-oxidizing bacteria at very low oxygen concentrations (2-8 microM) provided that ammonium was the limiting N compound. When ammonia was in excess of oxygen, the nitrite-oxidizing bacteria were washed out of the reactors, and ammonium was converted to mainly nitrite, nitric oxide and nitrous oxide by Nitrosomonas-related bacteria. The situation could be rapidly reversed by adjusting the oxygen to ammonium ratio in the reactor. In batch and continuous tests, no inhibitory effect of ammonium, nitric oxide or nitrous oxide on nitrite-oxidizing bacteria could be detected in our studies. The recently developed oxygen microsensors may be helpful to determine the kinetic parameters of the nitrifying bacteria, which are needed to make predictive kinetic models of their competition.
authors.affiliation: Department of Biotechnology, Faculty of Applied Science, Delft University of Technology, Julianalaan 67, 2628 BC, Delft, The Netherlands.
authors.forename: A Olav
authors.initials: AO
authors.lastname: Sliekers
authors.forename: Suzanne C M
authors.initials: SC
authors.lastname: Haaijer
authors.forename: Marit H
authors.initials: MH
authors.lastname: Stafsnes
authors.forename: J Gijs
authors.initials: JG
authors.lastname: Kuenen
authors.forename: Mike S M
authors.initials: MS
authors.lastname: Jetten
mesh_terms: D000641:Ammonia / Q000494:pharmacology / Q000633:toxicity; D001420:Bacteria, Aerobic / Q000254:growth & development* / Q000378:metabolism; D018533:Biomass; D019149:Bioreactors; D003470:Culture Media; D007700:Kinetics; D009573:Nitrites / Q000378:metabolism*; D009609:Nitrous Oxide / Q000494:pharmacology / Q000633:toxicity; D010084:Oxidation-Reduction; D010100:Oxygen / Q000494:pharmacology*; D000644:Quaternary Ammonium Compounds / Q000378:metabolism*
chemical_list: D003470:Culture Media; D009573:Nitrites; D000644:Quaternary Ammonium Compounds; D000641:Ammonia; D009609:Nitrous Oxide; D010100:Oxygen