The Purification And Breeding Of High-yield Biosurfactant Strains

Biosurfactant is a surface active sexual material produced by microorganism. Compared with chemical surfactant, biosurfactant has lots of advantages, such as environment compatibility, non-toxic, complete biodegradability, no polluting to environment, reducing the surface tension. Biosurfactant has been gradually applied in all fields, particularly in petroleum and environmental fields. Many biosurfactants and their producing processes have been studied deeply and widely.In this article, the strains which can produce biosurfactants efficiently was isolated from soil polluted by petroleum by a series of steps including determination of surface tension, oil spreading method, hemolytic activity assay on blood agar plates and so on. Four strains numbered64,89,109,112were obtained.The fermentation condition for production of biosurfactant was optimized by single-factor experiments. For strain64, the most suitable growing conditions can be summarized as following:carbon source is vegetable oil, sourse of nitrogen is yeast and peptone, temperature is30℃, pH value is8, the salt concentration is0.5%-2%, the amount of liquor is30mL; For strain89, the most suitable growing conditions can be summarized as following:carbon source is paraffin, sourse of nitrogen is yeast, temperature is30℃, pH value is7.3, the salt concentration is0.5%-2%, the amount of liquor is25mL; For strain109, the most suitable growing conditions can be summarized as following:carbon source is vegetable oil, sourse of nitrogen is yeast and peptone, temperature is30℃, pH value is7.3, the salt concentration is0.5%-1%, the amount of liquor is35mL; For strain89, the most suitable growing conditions can be summarized as following:carbon source is paraffin, the sourse of nitrogen is yeast and peptone, the temperature is20℃, the pH value is7.3, the salt concentration is 0.5%-1%, the amount of liquor is30mL.The emulsification, biosurfactant type and composition of the four strains were obtained by testing the emulsified volume, methylene blue-chloroform and TLC experiment, respectively. The emulsified volumes of the four strains are all more than80%and emulsification is stable. All biosurfactant that they produced are anionic Glycolipid and biosurfactant.