ISOLATION, OPTIMIZATION AND CHARACTERIZATION OF PETROL DEGRADING BACTERIA FROM OIL CONTAMINATED SOIL SAMPLESCHALLARAJ EMMANUEL, E.S., SANIYA S. DAVIS AND GINI GEORGE, V.Abstract Bacterial strains were isolated from the crude oil contaminated soil sample using serial dilution method. Among 55 bacterial colonies one bacterial strain was identified based on the cultural, morphology and biochemical characteristics. This strain was identified as Brevibacterium brevis by further using 16s r-RNA sequencing. The isolated bacterium was then subjected to a preliminary assessment of their crude oil degradation efficiency. After 48 h of incubation, on nutrient agar plates overlaid with 100 L of petroleum crude oil, the zone of clearance was observed. The bacterial isolate showed an average zone of clearance of 6mm in diameter on taking triplicates. Estimation of crude oil degradation by gravimetric analysis for the isolate at four different oil concentrations was performed. The isolated bacteria showed a 35% petrol degradation, whereas a relatively high oil degradation rate, almost 40% was observed when the bacterium was acclimatized. Brevibacterium brevis showed a significant rate of crude oil degradation when compared to the control organism which confirms that biodegradation of hydrocarbon was exhibited by this isolate. The selected bacterial strains crude oil resistance was analyzed based on the growth ability on the crude oil containing mediums. The growth ability was measured from after inoculation and the highest percentage of petrol degradation occurred at temperature 37 °C with the value being 30.8%.
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