Polycyclic aromatic hydrocarbons (PAHs) are of the group of aromatic compounds having interlocking rings. They enter to environment due to incomplete combustion of fossil fuels. Having the toxic and carcinogen characteristic, PAHs are of the factors which threaten the environment. some of the bacteria with particular mechanism are able to degrade these compounds. The goal of this study is to evaluate the biological modification of naphthalene using native bacteria isolated from oil contaminated soils in Iran and to assess their growth kinetic. Several naphthalene-degrading bacteria were isolated from oil-contaminated soil in a crude oil extraction and desalination center in Omidieh, Ahvaz, Iran. Bacterial strains which had better growth on the enriched medium were isolated and identified by biochemical and morphological tests. The findings of this study show that most of the isolated bacteria were found to belong to Staphylococcus sp, Corynebacterium sp, Pseudomonas sp, Bacillus sp, and Micrococcus sp. These species were significantly able to degrade naphthalene. The efficiency of naphthalene as the only source of carbon and energy was evaluated by High performance liquid chromatography (HPLC) analysis. HPLC analysis showed that the Bacillus sp and Pseudomonas sp, 86% and 80%,Corynebacterium sp and Staphylococcus sp, 77% and 69% and Micrococcus sp, 58% degrade the naphthalene after one week incubation respectively.
