Ammonium and methylammonium uptake in a fertilizer-degrading strain of Ochrobactrum anthropi

• Published in: Antonie van Leeuwenhoek 2000-04, Vol.77 (3), p.263-270
• Main Authors: EWEN, H, KALTWASSER, H, JAHNS, T
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; ammonia; Ammonium; Biochemistry and biology; Biodegradation, Environmental; Biological and medical sciences; Biological Transport; Carbon Isotopes - metabolism; Carbonyl Cyanide m-Chlorophenyl Hydrazone - pharmacology; Chemical, physicochemical, biochemical and biological properties; Chromatography, High Pressure Liquid; Cytoplasm - chemistry; Fertilizers; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Bacterial; Glutamates - metabolism; Hydrogen-Ion Concentration; Kinetics; Mass spectrometry; Metabolites; Methylamines - metabolism; methylammonium; Microbiology; Nitrogen sources; Ochrobactrum anthropi; Ochrobactrum anthropi - metabolism; Physics, chemistry, biochemistry and biology of agricultural and forest soils; Poisons; Quaternary Ammonium Compounds - metabolism; Radioactive Tracers; Soil Microbiology; Soil science; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Temperature; Thin layer chromatography; Uncoupling Agents - pharmacology
• ISSN: 0003-6072; 1572-9699
• DOI: 10.1023/A:1002472120258

The transport of ammonium and methylammonium was studied in a strain of Ochrobactrum anthropi, a microorganism isolated from garden soil and able to degrade methyleneureas which are used as slow-release nitrogen fertilizer. The activity of both transport systems was determined using [14C]methylammonium. Differences between the two transport systems were observed with regard to their pH- and temperature dependence as well as their kinetic parameters and regulation during growth with various nitrogen sources. Ammonium transport was subject to repression by ammonium and to derepression in its absence, while the methylammonium carrier was induced in the presence of methylamine. The ammonium but not the methylammonium transport system was severely inhibited by ammonium, and metabolic poisons inhibited both uptake systems. The analysis of intracellular metabolites using thin-layer chromatography and matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry indicated that methylammonium was rapidly metabolized to N-methylglutamate via gamma-N-methylglutamine.