Production and applications of lipopeptide biosurfactant for bioremediation and oil recovery by Bacillus subtilis CN2

Petroleum compounds are recalcitrant to microbial degradation and persist in ecosystems because of their high hydrophobicity. Lipopeptide biosurfactant was produced by hydrocarbon degrading and biosurfactant producing strain isolated from creosote contaminated soil. The isolate CN2 was identified as Bacillus subtilis using 16S rRNA gene sequencing. In a used motor oil degradation assay carried out in an Erlenmeyer flask using microbial consortium, the biosurfactant enhanced the degradation of used motor oil polycyclic aromatic hydrocarbon (PAH) components up to 82% in 18 days of incubation, more than twofold compared to the degradation with no biosurfactant supplementation. The biosurfactant was tested for its oil recovery potential and it recovered 85% of used motor oil from contaminated sand in 24h. Tandem mass spectrometry (LC-MS/MS), Thin-layer chromatography (TLC) and Fourier transform infrared spectroscopy (FTIR) analysis showed that the biosurfactant produced is lipopeptidal of molecular mass 1472 Da. The lipopeptide showed emulsifying activity against a variety of hydrocarbons and attained emulsion indices of 81 and 84% with Hexane and cyclohexane, respectively. The lipopeptide showed stability over a temperature range of (25-125 degrees C), pH range of (5-12) and salinity range of (5-20%, w/v). The results reveal the potential of the biosurfactant for use in bioremediation of hydrocarbon contaminated environmental media and washing of petroleum sludge contaminated soil. (C) 2015 Elsevier B.V. All rights reserved.