ABSTRACT
A mathematical model which describes the effect of pH and dissolved oxygen on growth and activity of Nitrosomonas and Nitrobacter in mixed culture is presented. A good fit is obtained between experimental data and theoretical curves computed with parameters estimated by independent methods. Experimental data together with simulation studies show that inadequate aeration induces a temporal shift of ammonium and nitrite oxidations resulting in a transient nitrite accumulation similar to that caused by an increase of temperature.
Subject(s)
Nitrobacter/metabolism , Nitrogen/metabolism , Nitrosomonas/metabolism , Oxygen , Hydrogen-Ion Concentration , Models, Biological , Nitrites/metabolism , Nitrobacter/growth & development , Nitrosomonas/growth & development , Partial Pressure , TemperatureSubject(s)
Nitrobacter/growth & development , Calorimetry , Cell Count , Culture Media , Hot Temperature , Mathematics , Nitrates , Nitrites , Oxidation-Reduction , ThermodynamicsSubject(s)
Freezing , Histological Techniques , Microscopy, Electron , Nitrobacter/cytology , Cell Membrane , Cell Wall , Cytoplasm , Cytoplasmic Granules , Freeze Etching , Hydroxybutyrates , Phosphates , PolymersSubject(s)
Nitrobacter/metabolism , Nitrosomonas/metabolism , Bacteriological Techniques/instrumentation , Calorimetry , Carbon Dioxide/metabolism , Cyanides/pharmacology , Dinitrophenols/pharmacology , Hot Temperature , Nitrobacter/drug effects , Nitrosomonas/drug effects , Oxygen Consumption , Quinacrine/pharmacologyABSTRACT
The reduction levels of cytochrome c and a(1) in intact Nitrobacter cells and cell-free extracts, during and after nitrite or formate oxidation, were examined in combination with the amperometric measurement of oxygen uptake. Quite different reduction patterns were observed when comparing nitrite oxidation by intact cells and cell-free extracts. An inverse relationship was observed between the rate of electron flow and the steady-state reduction level of cytochrome a(1). Parallel observations on nitrite oxidation, by use of formate and reduced nicotinamide adenine dinucleotide as electron donors, showed the influence of the high oxidation-reduction potential of the nitrite-nitrate system on cytochrome reduction. A value for the apparent activation energy of the overall nitrite oxidation process, amounting to 15 kcal, was found in a study of the temperature dependence of cytochrome reduction.
