Among 348 microbial strains isolated from petroleum hydrocarbon-contaminated soil, five were selected for their ability to produce biosurfactant based on battery of screening assay including hemolytic activity, surface tension reduction, drop collapse assay, emulsification activity, and cell surface hydrophobicity studies. Of these, bacterial isolate DSVP20 was identified as Pseudomonas aeruginosa (NCBI GenBank accession no. GQ865644) based on biochemical characterization and the 16S rDNA analysis, and it was found to be a potential candidate for biosurfactant production. Maximum biosurfactant production recorded by P. aeruginosa DSVP20 was 6.7 g/l after 72 h at 150 rpm and at a temperature of 30 °C. Chromatographic analysis and high-performance liquid chromatography-mass spectrometry (HPLC-MS) revealed that it was a glycolipid in nature which was further confirmed by nuclear magnetic resonance (NMR) spectroscopy. Bioremediation studies using purified biosurfactant showed that P. aeruginosa DSVP20 has the ability to degrade eicosane (97%), pristane (75%), and fluoranthene (47%) when studied at different time intervals for a total of 7 days. The results of this study showed that the P. aeruginosa DSVP20 and/or biosurfactant produced by this isolate have the potential role in bioremediation of petroleum hydrocarbon-contaminated soil.
Keywords: Biodegradation; Biosurfactants; Petroleum hydrocarbons; Pseudomonas aeruginosa.