Application of biosurfactant for enhancement of bioremediation process of crude oil contaminated soil

In the present study, a biosurfactant produced by Pseudomonas aeruginosa SR17 was utilized to evaluate its efficiency in enhancement of bioremediation of oil contaminated soil. The degradation of total petroleum hydrocarbon (TPH) on application of rhamnolipid biosurfactant at 1.5 g L-1 was found to be 86.1% and 80.5% in two soil samples containing 6800 ppm and 8500 ppm TPH respectively. The efficiency of biosurfactant was also compared with a frequently used synthetic surfactant, sodium dodecyl sulphate (SDS) that resulted in 70.8% and 68.1% degradation of TPH from the same contaminated soil samples. GC-MS based analysis showed the presence of poly aromatic hydrocarbons (PAHs) namely indene, chamazulene, naphthalene, phenanthrene, anthracene, fluorene, floranthene, benz(b)fluorene and benz(d)anthracene in the soil samples. Ithamnolipid treatment eliminated 3 PAHs namely floranthene, benz(b)fluorene, and benz(d)anthracene completely within six months and the remaining PAHs were depleted up to 60-80%, within the same period. The efficient degradation of PAHs and other components of TPH on application of the biosurfactant were attributed to enhanced heterotrophic bacterial population. It was also found that the degradation of oil contaminants led to alteration of certain vital physico-chemical properties of the soil.