Degradation of anthracene by bacteria isolated from oil polluted tropical soils

Abstract

Four bacteria, identified as Pseudomonas aeruginosa, Alcaligenes eutrophus, Bacillus subtilis and Micrococcus luteus were isolated from crude oil polluted soils using anthracene as the sole carbon and energy source. All the organisms utilized n-hexadecane, n-tetradecane, diesel oil, engine oil and naphthalene as sole carbon sources. None could utilize hexane, cycloheptane, xylene, benzene, toluene, phenol, fluoranthene, and kerosene as carbon sources. Highest cell density obtained with 0.1% (w/v) anthracene were 4.5 × 107 (cfu/ml), 8.6 × 106 (cfu/ml), 5.4 × 106 and 2.4 × 106 (cfu/ml) respectively, for P aeruginosa, A eutrophus, B. subtilis and M. luteus after 30 days incubation. Growth of the organisms on a Nigerian crude oil resulted in a residual oil concentration of 22.2%, 33.3%, 39.3%, 44% and 91.7% respectively, for P aeruginosa, A. eutrophus, B. subtilis, M. luteus and the noninoculated control on the 14 th day. Ring fission enzymes of the meta pathway were detected in induced cells of P. aeruginosa and A. eutrophus while ortho pathway enzymes were detected in B. subtilis and M. luteus. P aeruginosa and A. eutrophus had specific catechol-2,3-dioxygenase activities of 3.8 ± 0.183 and 0.64 ± 0.032 μmol / min x mg protein respectively while catechol-1,2-dioxygenase activities of 1.95 ± 0.029 and 1.89 ± 0.026 μmol / min × mg protein were detected in B. subtilis and M. luteus respectively. This work, highlights the capability of these unreported tropical strains of A. eutrophus, B. subtilis and M. luteus as anthracene degraders.