Enrichment techniques led to the isolation of a Pseudomonas sp. strain P2 from municipal waste-contaminated soil sample, which could utilize different isomers of a commercial mixture of 4-nonylphenol when grown in the presence of phenol. The isolate was identified as Pseudomonas sp., based on the morphological, nutritional, and biochemical characteristics and 16S rDNA sequence analysis. The ${eta}$-ketoadipate pathway was found to be involved in the degradation of phenol by Pseudomonas sp. strain P2. Gas chromatography-mass spectrometric analysis of the culture media indicated degradation of various major isomers of 4-nonylphenol in the range of 29-50%. However, the selected ion monitoring mode of analysis of biodegraded products of 4-nonylphenol indicated the absence of any aromatic compounds other than those of the isomers of 4-nonylphenol. Moreover, Pseudomonas sp. strain P2 was incapable of utilizing various alkanes individually as sole carbon source, whereas the degradation of 4-nonylphenol was observed only when the test organism was induced with phenol, suggesting that the degradation of 4-nonylphenol was possibly initiated from the phenolic moiety of the molecule, but not from the alkyl side-chain.