Mechanism of nitrification by Arthrobacter sp.
Resting cells of Arthrobacter sp. excrete as much as 60 mug of hydroxylamine-nitrogen per ml when supplied with ammonium. An organic carbon source in abundant supply is necessary for the oxidation. Resting cells oxidize hydroxylamine to nitrite and 1-nitrosoethanol, the former accumulating only when an exogenous carbon source is available. Cell-free extracts contain an enzyme catalyzing the formation of hydroxylamine from acetohydroxamic acid, a hydroxylamine-nitrite oxido-reductase, and an enzyme producing nitrite and nitrate from various primary nitro compounds. Nitrite is not produced from hydroxylamine by the extracts, but 1-nitrosoethanol is formed from hydroxylamine in the presence of acetate. 1-Nitrosoethanol is also produced from acetohydroxamic acid by these preparations. Nitrite was formed from hydroxylamine, however, by extracellular enzymes excreted by the bacterium.
D000085:Acetates / Q000378:metabolism; D000641:Ammonia / Q000378:metabolism; D001173:Arthrobacter / Q000201:enzymology / Q000254:growth & development / Q000378:metabolism*; D002374:Catalase / Q000378:metabolism; D002474:Cell-Free System; D003470:Culture Media; D000431:Ethanol / Q000096:biosynthesis; D006877:Hydroxamic Acids / Q000096:biosynthesis; D006898:Hydroxylamines / Q000096:biosynthesis / Q000378:metabolism; D009566:Nitrates / Q000096:biosynthesis; D009573:Nitrites / Q000096:biosynthesis; D009574:Nitro Compounds / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism*; D009603:Nitroso Compounds / Q000096:biosynthesis; D010084:Oxidation-Reduction; D010544:Peroxidases / Q000378:metabolism
D000085:Acetates; D003470:Culture Media; D006877:Hydroxamic Acids; D006898:Hydroxylamines; D009566:Nitrates; D009573:Nitrites; D009574:Nitro Compounds; D009603:Nitroso Compounds; D000431:Ethanol; D000641:Ammonia; D010544:Peroxidases; D002374:Catalase; D009584:Nitrogen