Screening Of Biosurfactant Producer And Emulsifying Crude Oil By Fermentation Broth

Compared with chemical surfactant, biosurfactant has obtained international attentionbecause of its environment compatibility and broad application potential. Therefore, theexploitation of biosurfactant producter sources, andThe study on its mechanisms hasextremely important theoretical and practical significance for improving and perfectingMEOR。In this study, three strains of bacteria were isolated from the soil contaminated bypetroleum hydrocarbon. Strain31#was indentified as Pseudomonas, and strain37#and strain47#as Bacillus according to their physiological and biochemical characteristics. The strainsscreened grew on liquid paraffin as the sole carbon source of liquid culture，and the biomass,pH and surface tension of culture broth and cell hydrophobicity were determined. During thefermentation of strains31#,37#and47#, the surface tension of culture broth could reduce to49.47mN/m,58.00mN/m and56.04mN/m, pH changed between7.0and7.5. The strainsdisplayed second growth and could reach their maximum hydrophobicity3.09%,1.49%and1.66%.In this paper, the biosurfactant produced by strains31#,37#and47#were analyzed byusing thin-layer chromatography.，and identified as rhamnolipid rhamnolipid yield were0.365g/L,0.264g/L and0.235g/L.The optimal growth temperature of strain31#was around40℃. The strain31#had washighest hydrophobicity when it was cultured at50℃.And the surface tension of fermentationbroth was minimum when cultured at60℃. The biomass of strain37#was lower whencultured at60℃, but the surface tension of fermentation broth decreased obviously. Thetemperature had not obvious effect. Growth of strain47#sensitive to culture temperature, thehydrophobicity and pH of fermentation broth could reach a maximum value at30℃.Strain37,liquid paraffin,endogeneous microorganism and biosurfactant emulsification forcrude oil could emulsify crude oil on different degree, emulsification of biosurfactant waslower than that of liquid paraffin,but biosurfactant can reduce the surface tension of culture broth with crude oil. Strain37#could peel-off crude oil. Endogeneous microorganism couldnot only emulsify for crude oil but also reduc the pH value of culture broth with crude oil.