Study On Biosurfactants Produced By Hydrocarbon- Utilizing Microorganism(s)

Abstract

microbial surfactant (biosurfactant) was investigated for its potential to enhance bioavailability and , hence, the biodegradation of n-alkanes or saturate hydrocarbons from different sources such as gas oil or crude petroleum . The rhamnolipids biosurfactant used in this study was extracted from culture supematants after growth of Pseudomonas aeruginosa I in phosphate limited proteose peptone glucose ammonium salt (PPGAS) medium as the optimum biosurfactant producing medium . Cell hydrophobicity was determined by a modified bacterial adherence to hydrocarbon (BATH) assay. Bacterial adherence to hydrocarbon quantitates the preference of cell surfaces for the aqueous phase or the aqueous-n-hexadecane interface in a two-phase system of water and n• hexadecane. ['C]-rhamnolipids concentrations were determined in order to indicate the presence of [14C] -rhamnolipids in medium or bacterial cells . Dispersion of gas oil n-alkanes in aqueous solutions was dramatically enhanced by 200 mg. of the rhamnolipids biosurfactant per liter. Biodegradation experiments were done with five different treatments under different incubation times, 3 and 6 days using different carbon sources. The results obtained indicate that the Pseudomonas rhamnolipids biosurfactant has great potential for facilitating the bioremediation of sites contaminated with hydrocarbons (especially those of petroleum origin) having limited water solubility.