Characterization of the biosurfactant produced by Pesudomonas areuginosa strain R4 and its application for remediation pyrene-contaminated soils

A biosurfactant producing strain was isolated and the rhamnolipid type biosurfactant was extracted for soil washing of a synthetically and naturally hydrocarbon-contaminated soil. Following the primary screening, Pseudomonas aeruginosa strain R-4 was selected and the effect of the carbon and nitrogen source and the salinity on biosurfactant production was studied. Of the best results were observed for glucose as a carbon source, NH4Cl as a nitrogen source and salinity of 1.4%. The produced biosurfactant was a glycolipid type biosurfactant and reduced the surface tension to 32.5 mN/m with a critical micelle concentration (CMC) of 50 mg/L and production yield of 90 mg/L. Using produced biosurfactant, a pyrene desorption rate of 82% was observed in selected conditions for initial pyrene concentration of 200 mg/L.