Fermentation Conditions And Separation Of Bioemulsifier From Ochrobactrum Intermedium

Bioemulsifiers have advantages, such as environmental compatibility, biodegradability and low toxicity, and have been applied in many fields. The research of fermentation condition and characteristics of bioemulsifier have important significance.In this work, the effect of environmental condition and carbon source on fermentaion of the bioemulsifier-producing bacterium Ochrobactrum intermedium 1#, the separation, component, characteristics and application of bioemulsifier prod uced by the strain were studied.The strain 1# could survive at 0-45 oC, pH 5-12 and 1.0-8.0% NaC l. The optimum condition for bioemulsifier production was 30 oC, pH 7-8 and free of NaC l, respectively. The cell growth was stimulated while bioemulsifer was not produced with 1.0-2.0% NaCl.The emulsification index of the fermentation broth with 1.0% sucrose as sole carbon was 56% on the 6th day. The strain could grow excessively and rapidly with 2.0% sucrose while synthesize bioemulsifier poorly. The biomass and the emulsification index could not increase with the mixed carbon of 1.0% sucrose and 0.5-1.0% soybean oil.The bioemulsifier producted by the strain was extracted by adjusting cell free broth to pH 10-12 in order to remove proteins. The bioemulsifier could be precipited by adding two volumes of cold ethanol into supernatant. This precipitate was washed three times with 67% ethanol of 1/10 volume of supernatant and then dissolved in deionized water of 1/10 volume of cell free broth and standed at 4 oC for 40 min for crystallization. Bioemulsifier crystal was identified to be a complex of carbohydrates and protein by chemical analysis and thin- layer chromatography analysis.The bioemulsifier belonged to anionic bioemulsifier and could not foam, but enhanced foam durability of egg white. The bioemulsifier was stable under the condition of-20-140 oC, pH 2-13 and 1-30% NaCl. The bioemulsifier showed emulsification activity against liquid paraffin and vegetable oil while no emulsification activity against short chain hydrocarbon, and formed oil- in-water emulsion layer with liquid paraffin. The bioemulsifier was beneficial to extracting crude oil and cleaning vegetable oil, and layed the foundation for application in crude oil exporation and detergent field.