Strain DN002 isolated from petroleum-contaminated soil was identified as Achromobacter xylosoxidans based on morphological and biochemical properties and 16S rRNA phylogeny, and investigated for its potential to utilize numerous polycyclic aromatic hydrocarbons (PAHs) such as fluoranthene and pyrene as sole carbon and energy resource. Biodegradation studies showed that 500 mg(.)l(-1)fluranthene was degraded to 35.6 +/- 0.3 mg(.)l(-1) by DN002 after 14 days incubation. During fluoranthene biodegradation, catechol 2,3 dioxygenase (C23O) activity was augmented 1.5 times more than catechol 1,2 dioxygenase (C12O), which indicated that C23O played a major role in fluoranthene degradation by DN002. Protein profiles were examined by sodium dodecyl sulfate polyacrylamide gel electrophoresis and two-dimensional electrophoresis then analyzed by mass spectrometry induced by fluoranthene; a molecular mass range of 18 similar to 66 kDa proteins were found upregulated compared with the uninduced control sample, including multiple isoenzymes of beta-oxidation and dehydrogenases as well as dioxygenases. Besides, some new proteins, i.e., dihydrolipoamide succinyltransferase and aldehyde dehydrogenase family proteins and isocitrate lyase were also synthesized.