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Bioremediation of crude oil contaminated soil by Pseudomonas aeruginosa strain-O2 and Micrococcus varians strain-X with different approaches

Mahmoud M.Berekaa, Alaa Mostafa, Abdel-Rahman Alaa

The efficiency of two bacterial candidates namely; Pseudomonas aeruginosa strain-O2 and Micrococcus varians strain-X, in degradation of crude oil extracted fromcontaminated sediment samples was evaluated. GC-analysis of the degradation products indicated that both strains were able to use crude oil as carbon and energy source.Aliphatic hydrocarbon fraction of the sediment extract, especially long chain alkanes (n-C22+), was degraded. For aromatic hydrocarbon fraction, namely methyl naphthalene compound, both strains were able to degrade 2,3,6- and 1,2,5- trimethyl naphthalenes to a comparable extent. Only P. aeruginosa strain- O2 was able to utilize 1,3,7- trimethyl naphthalene, whileM. varians strain- X was able to use 1,2,4- trimethyl naphthalene as a sole C-source. Application of different strategies in bioremediation of sea sand contaminated with 10%crude oil indicated that the bioaugmentation with mixed culture of both strains was the optimal treatment strategy (approximately 93.45%).While, treatment applying either one of the two strains indicated that M. varians strain-X is more efficient in crude oil degradation. Comparable to that of natural conditions, biostimulation resulted in limited crude oil removal (approximately 36.42%). Results collectively indicated that the bacterial strains used in this study were suitable candidates for practical field application and in situ bioremediation, namely by bioaugmentation.