Abstract

Potential mineral oil degrading bacterial isolates (Pseudomonas putida, Rhodococcus erythroplolis and Bacillus thermoleovorans) were studied from the contaminated soils.The bacterial populations of these polluted soils were 5.25 × 10⁵, 1.76 × 10⁶ and 5.11 × 10⁵ CFU/ml with three different colony types of bacterial strains, respectively. Microbial population diversity studies were carried out by microbial enumeration, identification, and determination of growth responses of bacterial isolates in different concentrations of mineral oil sample. Phenotypic examination of the heterotrophic bacteria belonged mainly to the genus Pseudomonas, Rhodococcus and Bacillus. The mixed populations are capable of degrading mineral oil up to 120 ppm. Mineral oil biodegradation was fast by the mixed culture comparing to the biodegradation of each strain separately. Since the biological treatment can efficiently destroy the hydrocarbons and does not allow the contaminant to accumulate, it is considered to be a superior technology. This study revealed that the mixed bacterial consortium achieved maximum crude oil degradation at pH 7. Hence, it is suggested that the use of the aforementioned mixed bacterial consortium under optimized conditions will be an effective and eco-friendly technology for the degradation of hydrocarbons from BH crude oil.

Key words: Mineral oil, biodegradation, Pseudomonas putida, Rhodococcus erythroplolis,Bacillus thermoleovorans.