Bioremediation of Polycyclic Aromatic Hydrocarbon Contaminated Soil by a Microbial Consortium through Supplementation of Biosurfactant Produced by Pseudomonas aeruginosa Strain

Lipopeptide biosurfactant produced by Pseudomonas aeruginosa Lbp 3 strain isolated from petroleum contaminated soil was investigated for its potential to enhance bioavailability, and hence, the biodegradation of polycyclic aromatic hydrocarbons (PAHs) in contaminated soil microcosms. Experiments were conducted on a soil spiked with equal parts of the PAHs Phenanthrene, Fluoranthene, and Pyrene to a final concentration of 1200mg of total PAHs per kg of dry soil. To evaluate biodegradation enhancement efficiency, 50g spiked soil samples were supplemented with 50 mgL(-1), 100 mgL(-1), 300 mgL(-1), and 1000 mgL(-1)of lipopeptide dissolved in 30mL of MSM, and incubated for 40days at 30 degrees C in darkness. Statistically significant (P < 0.05) biodegradation rates were observed in all the amended microcosms in comparison to the unamended controls. Maximal biodegradations (> 96% of Phenanthrene and Fluoranthene and > 93% of Pyrene) were observed in the soil microcosms supplemented with 1000 mgL(-1)and 50 mgL(-1) lipopeptide. The effect of substrate interactivity of the PAHs on the biodegradation kinetics was also tested in comparison with sole substrate microcosms. Competitive inhibition of the biodegradation of low molecular weight PAHs was observed as a result of substrate interactivity in the multisubstrate system.