Diesel Biodegradation Capacities of Bacillus subtilis OR632422, Micrococcus luteus OR632421 Isolated From petroleum-Contaminated Soil

Bacterial candidates were isolated from soil contaminated by petroleum and these isolates were evaluated for their ability to degrade diesel from which twelve bacterial isolates showed growth magnitude of ≤ 8.16 log CFU/ml. The two most promising microbial candidates (S1 and S3) showed the highest growth of 8.16 and 7.98 Log CFU/ml and were phylogenetically analyzed and uploaded in GenBank as Bacillus subtilis and Micrococcus luteus strains with GenBank accession no. OR632422 and OR632421, respectively. B. subtilis and M. luteus emulsification indices recorded were 72.22% and 65.56%, respectively. Worthy to mention that optimal growing conditions in presence of 4% diesel fuel (v/v) for both strains were achieved at pH 7, with optical densities maximum values of 1.007 and 0.85 for B. subtilis and M. luteus, respectively. After 14 days the maximum values for biodegradation percent of added diesel fuel achieved by B. subtilis and M. luteus were 70.74 and 54.63 %, respectively. Ultimately, the current study demonstrated that out of the twelve bacterial isolates only two identified strains of which B. subtilis was more effective in degrading diesel oil than M. luteus.