Ammonium and hydroxylamine uptake and accumulation in Nitrosomonas.
Starved cells of Nitrosomonas europaea and further ammonia oxidizers were able to rapidly accumulate ammonium and hydroxylamine to an internal concentration of about 1 and 0.8 M, respectively. In kinetic studies, the uptake/accumulation rates for ammonium [3.1 mmol (g protein)(-1) min(-1)] and hydroxylamine [4.39 mmol (g protein)(-1) min(-1)] were determined. The uptake and accumulation process of ammonium and hydroxylamine was not coupled to ammonia or hydroxylamine oxidation and nitrite was not produced. In the presence of uncouplers the ammonium accumulation was completely inhibited, indicating an active, membrane-potential-driven transport mechanism. When the external ammonium or hydroxylamine pool was depleted, the internal ammonium and hydroxylamine was consumed within 12 h or 20 min, respectively. The binding of ammonium/ammonia was correlated with an energized membrane system, and hydroxylamine may bind to the hydroxylamine oxidoredutase.
Schmidt
Ingo
I
Department of Microbiology, University of Bayreuth, Universitaetsstrasse 30, 95447 Bayreuth, Germany.
Look
Christiane
C
Department of Microbiology, University of Hamburg, Ohnhorststrasse 18, 22609 Hamburg, Germany.
Bock
Eberhard
E
Department of Microbiology, University of Hamburg, Ohnhorststrasse 18, 22609 Hamburg, Germany.
Jetten
Mike S M
MSM
Department of Microbiology, University of Nijmegen, Toernooiveld 1, 6525 ED Nijmegen, The Netherlands.
D003470:Culture Media; D015964:Gene Expression Regulation, Bacterial; D019811:Hydroxylamine / Q000378:metabolism*; D009573:Nitrites / Q000378:metabolism; D009587:Nitrogen Isotopes / Q000378:metabolism; D009606:Nitrosomonas / Q000378:metabolism* / Q000502:physiology; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000378:metabolism; D000644:Quaternary Ammonium Compounds / Q000378:metabolism*
D003470:Culture Media; D009573:Nitrites; D009587:Nitrogen Isotopes; D000644:Quaternary Ammonium Compounds; D019811:Hydroxylamine; D010088:Oxidoreductases