Pseudomonas putida I58 was isolated from soil by a conventional enrichment culture method using isoeugenol as a sole carbon source. The strain utilized isoeugenol, vanillin and vanillic acid as carbon sources. On the other hand, the intermediates of the eugenol-degrading pathway, such as eugenol, coniferyl alcohol, coniferyl aldehyde and ferulic acid, were not utilized by this strain, indicating that isoeugenol is directly degraded to vanillin without the formation of ferulic acid. The resting cells of P. putida I58 rapidly converted isoeugenol into vanillic acid via vanillin with a conversion yield of 98% by 40-min incubation.