Characterization and assessment of biosurfactant producing indigenous hydrocarbonoclastic bacteria: potential application in bioremediation

Abstract

Petroleum and hydrocarbons contamination can be remediated by physical, chemical or biological methods. Among these, in situ bioremediation is considered to be environmentally friendly because it restores the soil structure, requires less energy input and involves the notable removal after degradation of biosurfactant. The present study involves the characterization and assessment of biosurfactant producing indigenous hydrocarbonoclastic bacteria and their potential application in bioremediation processes. Three bacterial strains were isolated from various crude oil contaminated environments and characterized using standard identification techniques. The results clearly demonstrate the capability of utilizing hydrocarbon and biosurfactant produced by the bacterial strains. 16S rDNA sequencing followed by BLAST analysis revealed their similarity to Pseudomonas aeruginosa. The physico-chemical characterization of the biosurfactants revealed significant surface properties with stability at extreme temperature conditions (up to 121˚C), pH (5 - 8) and salinity (up to 4 %). Further, the mass spectrometry confirmed predominance of di-rhamnolipids in biosurfactant mixtures. The biosurfactants were found to be efficient in the removal of crude oil from the contaminated sand suggesting its applicability in bioremediation technology. Further, improved discharge of crude oil at elevated temperatures also confirms their thermo-stability which, could be exploited in microbial enhanced oil recovery processes. Thus, the applications of biosurfactants produced by the indigenous hydrocarbonoclastic strains appeared to be advantageous for bioremediation of petroleum-contaminated environments.