Isolation and Characterization of Crude-Oil Degrading Marine Bacteria and Assessment for Biosurfactant Production

Abstract: Ten crude oil degrading marine bacteria could be isolated from the sampling site in the ship-breaking yard at Alang coast, Gujarat. These isolates might belong to genera like Acinetabacter, Marinococcus, Micrococcus, Planococcus, Methylobacterium, Rhodoccus and Noccardia. All the isolates were inoculated in Bushnell Haas Medium containing 1% crude oil as carbon source for checking the biodegradation potential. Highest biodegradation was found to be 70% by the isolate M2, which most probably belongs to genus Marinococcus. Other isolates showed biodegradation in the range of 55-30%. On addition of chemical surfactant Tween 80 into the above medium only three isolates M3, M9 and M10 showed an enhancement in biodegradation of crude oil whereas biodegradation was decreased in case of rest of the isolates. 70% of the isolates showed a positive result for biosurfactant production after inoculation in mineral media for 7 days. Biosurfactant of most of the isolates showed demulsifying activity. Plasmid of around 10 kb size was found in the isolate M2 which showed highest biodegradation of crude oil. But this plasmid may or may not be responsible for conferring crude oil degrading property. This is because even after performing plasmid curing the isolate grew on mineral media agar plate containing crude oil sole carbon and energy source.