Potentials of mixed cultures of bacteria in the biodegradation of crude oil
This study aimed at exploring the potentials of mixed cultures of bacteria isolated from crude oil polluted sites for the biodegradation of crude oil. Mixed cultures of five bacterial isolates: Pseudomonas aeruginosa, P. putida, P. fluorescens, Bacillus subtilis and Micrococcus luteus were used for the crude oil biodegradation study. The degrading ability of the mixed cultures were assessed for duration of 28 days on a shaker at 300 rpm and at ambient temperatures (28±2 oC) in a mineral salt broth amended with 1% crude oil. Parameters used to assess the degradative abilities were pH, bacterial load, and residual crude oil contents. The result showed a significant increase in the bacterial count as the biodegradative study progressed while the pH and residual crude oil content decreased. The consortium of P. aeruginosa, P. putida, P. fluorescens, B. subtilis and M. luteus (CB1) was able to achieve reduction of crude oil to 92.4% followed by P. aeruginosa, P. putida, and P. fluorescens (CB2) with reduction of 89.5% in 28 days of biodegradative study. It is concluded from this study that the consortium CB1 were effective crude oil degraders. Thus, they are recommended for use in the bioremediation of polluted soils.
Key words: Polluted soils, Crude oil, Consortia, Bacteria, Biodegradation