Complex hydrocarbon and aromatic compounds degrading marine bacterial strains were isolated from
deep sea sediment after enrichment on spent engine (SE) oil. Phenotypic characterization and phylogenetic
analysis of 16S rRNA gene sequences showed the isolates were related to members of the Pseudoalteromonas
sp., Ruegeria sp., Exiguobacterium sp. and Acinetobacter sp. Biodegradation using 1% (v/v) SE oil
with individual and mixed strains showed the efficacy of SE oil utilization within a short retention time.
The addition of non-ionic surfactant 0.05% (v/v) Tween 80 as emulsifying agent enhanced the solubility of
hydrocarbons and renders them more accessible for biodegradation. The degradation of several compounds
and the metabolites formed during the microbial oxidation process were confirmed by Fourier
transform infrared spectroscopy and Gas chromatography–mass spectrometry analyses. The potential
of this consortium to biodegrade SE oil with and without emulsifying agent provides possible application
in bioremediation of oil contaminated marine environment.