Biodegradation of Baleym Mix crude oil in soil microcosm by some locally isolated Egyptian bacterial strains

Petroleum refining, transportation and storage are sources of soil contamination. In Egypt, a large number of contaminated sites exist as a result of different crude oil activities. In this work, biodegradation experiments in artificially oil contaminated soil microcosms (30 cm x 26 cm x 8 cm) of shallow polypropylene plastic trays were carried out with special emphasis on biodegradation of polycyclic aromatic hydrocarbons (PAHs). Two promising isolates, Pseudomonas aeruginosa I.1.1.6 and Brevibacterium casei I.2.1.7, previously isolated from Egyptian hydrocarbon contaminated soil, were used. The microcosms were inoculated at 30 degrees C for 60 days with a water content of 60%wt. TPH were quantitatively monitored, gas chromatographic (GC) and high performance liquid chromatographic (HPLC) analysis were preformed to follow up the biodegradation process. The results obtained indicate that after 60 days of incubation; Pseudomonas aeruginosa I.1.1.6 showed higher TPH biodegradation efficiency (64%) than that of Brevibacterium casei I.2.1.7 (58%). Bacterial isolates I.1.1.6 and I.2.1.7 showed total normal alkanes degradation of approximately 74% and 90%, respectively. Generally they are capable of degrading high molecular weight PAHs (five and six membered ring compounds, benzo[b]fluoranthene; BbF and indeno[1,2,3-cd]Pyrene, 1P, and have broad versatility in their action on the16PAH compounds currently regulated by the US Environmental Protection Agency (EPA) as priority pollutants, and could be useful in bioremediation of soil contaminated with crude oil.