Identification and characterization of a pseudomonas strain capable of metabolizing phenoxybenzoates.
3-Phenoxybenzoate is a transient metabolite from the breakdown of a number of pyrethroid insecticides in soil. In this study, we identified and characterized a bacterium which could grow on 3-phenoxybenzoate, converting it to phenol. On the basis of morphological and biochemical features, the 3-phenoxybenzoatedegrading isolate was determined to be a Pseudomonas species, probably a strain of Pseudomonas delafieldii, now designated Pseudomonas strain ET1. Pseudomonas strain ET1 grew on 3-phenoxybenzoate with a generation time of 3 h and a specific rate of metabolism of (2.6 +/- 0.9) x 10 g of 3-phenoxybenzoate consumed cell h. The K(m) for 3-phenoxybenzoate metabolism was 1.4 +/- 0.8 muM. The metabolism of 3-phenoxybenzoate was constitutive and not subject to catabolite repression. The metabolism of a variety of substituted diaryl ether compounds was examined. 3- and 4-Phenoxybenzoates were metabolized, but 2-phenoxybenzoate was not. Phenoxy-substituted benzyl aldehyde was metabolized, but phenoxy-substituted benzyl alcohol, benzene, phenol, and aniline were not. Derivatives of 3-phenoxybenzoate substituted in the 4' position with hydroxyl, methyl, or chlorine were metabolized, yielding the corresponding 4-substituted phenol. 3-(2-Hydroxyphenoxy)benzoate was not metabolized, but 3-phenoxy-4-fluorobenzoate was. These results indicate that the metabolism of the tested diaryl ether compounds was restricted to 4-phenoxybenzoate, 3-phenoxybenzyl aldehyde, and 3-phenoxybenzoate derivatives without a substitution in the 2' position.
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Land Resource Research Centre and Animal Research Centre, Research Branch, Agriculture Canada, Central Experimental Farm, Ottawa, Ontario, Canada K1A 0C6.
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