title: Metabolism of the herbicide bromoxynil by Klebsiella pneumoniae subsp. ozaenae.
abstract: Enrichment of soil samples for organisms able to utilize the herbicide bromoxynil (3,5-dibromo-4-hydroxybenzonitrile) as a nitrogen source yielded bacterial isolates capable of rapidly metabolizing this compound. One isolate, identified as Klebsiella pneumoniae subsp. ozaenae, could completely convert 0.05% bromoxynil to 3,5-dibromo-4-hydroxybenzoic acid and use the liberated ammonia as a sole nitrogen source. Assays of cell extracts of this organism for the ability to produce ammonia from bromoxynil revealed the presence of a nitrilase (EC 3.5.51) activity. The enzyme could not utilize 3,5-dibromo-4-hydroxybenzamide as a substrate, and no 3,5-dibromo-4-hydroxybenzamide could be detected as a product of bromoxynil transformation. Comparison of related aromatic nitriles as substrates demonstrated that the Klebsiella enzyme is highly specific for bromoxynil.
mesh_terms: D000619:Aminohydrolases / Q000378:metabolism; D007700:Kinetics; D007711:Klebsiella pneumoniae / Q000254:growth & development / Q000302:isolation & purification / Q000378:metabolism*; D009570:Nitriles / Q000378:metabolism*; D012988:Soil Microbiology; D013379:Substrate Specificity
chemical_list: D009570:Nitriles; D000619:Aminohydrolases; C076915:bromoxynil nitrilase; C006826:bromoxynil