Screening, Purification And Analysis Of A Strain Producted Glycolipid Surfactant

Biosurfactants has advantages of non-toxic and biodegradable which separate from surfactants. Biosurfactants also have emulsifying, dispersants, foaming, solubilization, sterilization and other functions. Current researches in various fields are gradually increasing. Glycolipid biosurfactants maybe one of the research. It maybe most likely alternative chemical surfactants products.In this study, using technique below: three dividing line separated on flat, enrich microorganisms, flat blood screening method for determination of the product and defination types. The strain comes from Daqing oilfield produced water samples. The experiment ultimately obtained a strain which product glycolipid surfactants. After morphological, physiological and biochemical experiments, 16 S r DNA sequence analysis, the strain QS-M2 is Pseudomonas aeruginosa, which produce the glycolipid of Rhamnolipid.The single factor of the fermentation medium was optimized. Finally carbon source is soybean oil 5%, nitrogen ammonium nitrate 0.6%, fermentation time of culture conditions is 120 h. Glycolipids poduction is 0.802 g/L. The optimition production increased 2.56 times compared with production before fermentation.Acid precipitation and organic solvent extraction are combined to extract surfactant. Silica gel column chromatography and dextran gel column chromatography method are used to purify biosurfactant extraction. Thin layer chromatography and concentrated sulfuric acid and phenol separation are used to identification of purified results. HPLC-MS is to identify the purified production. Physical and chemical properties of the production are texted. Experimental results show that the strain QS-M2 produced glycolipid which has single and double rhamnolipid. Single rhamnolipid have six main components: RhaC₁0C₁0, RhaC₁2C₁2, RhaC₁0C₁2, RhaC₁2, RhaC₁4, RhaC₈C₁0. The first two components are major production. Experiments show that single rhamnolipid which has two 8-12 carbon chain β-hydroxy fatty acid molecules are much more than that has one. Double rhamnolipids have three components : Rha₂C₁4C₁2, Rha₂C₁0C₁2, Rha₂C₁0C₁0. Among the three components, β-hydroxy fatty acid moiety with decreasing carbon chain length are reducing. Compared with the existing literature, the carbon chain length of double rhamnolipid main structure is longer.Interfacial tension, emulsification, drain ring assay are used to found the mixture rhamnolipid production which has good stability, high surface activity. The interfacial tension can down blank media from 72.0 m N/m to 36.9 m N/m, drop by 35.1 m N/m. As surfactant concentration increases, drain ring goes bigger and flooding capacity enhances. Rhamnolipid emulsifying properties of the highest value is 1.5mg/m L, emulsifying properties are stable within 72 h.