Studies On Screen, Performance And Application Of Biosurfactant Production Strain

Biosurfactants are a sort of natural amphoteric compounds,and mostly are some metabolites produced by microorganisms at certain culture conditions. Biosurfactants have attracted considerable interest in recent years due to their low toxicity,biodegradable nature,better environmental compatibility and high surfactivity and the physiologic except for reducing surface tension and stabling emulsifying ability,over chemical surfactants,specially in the repair of hydrocarbons pollutions.Because of the hydrophobic structure and toxicity of the hydrocarbon compounds limiting the repair.People hope to the biosurfactants could increase the effects of hydrocarbons environmental remediation.Therefore, biosurfactants have practical value to develop.In the paper,firstly an overview of the research history and status of biosurfactant.We filtered biosurfactants producing strains from the hydrocarbon degrading bacterias,optimized the fermentation conditions of producing biosurfactants,extracted biosurfactant from the fermentation broth of bacteria, identified and analysised its components,then applied in four biodegradable systems of diesel,pyrene,mixed hydrocarbon,and indoor oil-contaminated soil.Access to research findings about:(1) The optimal fermentation conditions of biosurfactant high-yield strain S5 were:glucose was carbon source of fermentation,pH 9,cultured for 76h.These were the best harvest of biosurfactant.(2) The purification biosurfactant arising from strain S5 was tan,such as melting sugar,viscous material,with good water solubility.The biosurfactant under the 40 times microscope showed complex filamentary structure.Its pure had 63.38% total sugar,34.6%rhamnolipid content,0.35%protein content.(3) The critical micelle concentration of biosurfactant arising from strain S5 was 30mg/L,corresponding to the surface tension of aqueous solution was 35.68mN/m~2.It could maintain its activity for 3h under 120℃,and could maintain its activity under 20%of NaCl aqueous solution.(4) The biosurfactant produced by strain S5 could enhance the diesel degradation rate of S5 by 15.2%,and enhance its pyrene degradation by 53.57%, adding 20mg/L biosurfactant solution could increase the mixed hydrocarbon total degradation rate of S5 by 20.04%,but adding excessive could inhibit degradation. The biosurfactant greatly promoted the degradations in the degradation system of strain S5 co-exist with strain R7.Especially for small water solubility of the anthracene,its degradation rate could increase by 40%.So that increased the diesel degradation rate of strain S9 and S10 which didn't produce biosurfactant by 21.2% and 6%.The result was the biosurfactant increased apparent solubility of polycyclic aromatic hydrocarbons.(5) In the repair of oil-contaminated soil experiment,adding the strain S5 broth could increase "Alfalfa-good bacteria" joint to repair of oil-contaminated soil by 22.5%,so that the repair efficiency of"Coronilla-good bacteria" had 20.68%raise.In this paper,the research could be applied to large-scale biological purification of hydrocarbon pollutions,oil recovery,and oil sludge treatment.The thesis research work laid the foundation for the application.