Crude oil degradation and biosurfactant production abilities of isolated Agrobacterium fabrum SLAJ731

Microbial biosurfactants have a wide range of applications as surface active agents. This study aimed to explore an indigenous bacterial strain, Agrobacterium fabrum SLAJ731, isolated from a core sample of Assam oil field for the biosurfactant production and biodegradation of crude oil, which were elucidated in terms of alkane hydroxylase (AH) activity. Preliminary screening was performed using drop collapse assay and oil displacement activity and culture conditions were optimized for biosurfactant production. The biodegradation of spent crude oil was explored under the optimized conditions in the presence of glucose as a co-substrate. The strain produced 5.77 +/- 0.3 g/L of biosurfactant under optimal conditions of pH 6 and 30 degrees C using glucose and yeast extract (C:N = 2:1) with high emulsification activity of 65 +/- 0.5%. The crude biosurfactant was characterized using FTIR and H-1 NMR and was found to be lipopeptide with a critical micelle concentration value of 650 mg/L and reduced surface tension to 34 +/- 0.5 mN/m. It was revealed from FTIR and GC-MS analyses that bacterium was able to degrade oil more efficiently in the presence of glucose and degraded aliphatic (47%) and aromatic hydrocarbons (70%) as compared to abiotic. Both extra and intra-cellular AH activities were found to enhance the biosurfactant production. This study puts forward a distinctive mechanism involved in the biosurfactant production and oil degradation, in the presence of a co-substrate. The notable lipopeptide production and oil degradation ability of A. fabrum endorse its suitability for bioremediation and other biotechnological applications.