| Summary: | 碩士 === 國立臺灣大學 === 農業化學研究所 === 83 === A bi-phase treatment system was developed based on biosurfactant producing strain, Pseudomonas aeruginosa 4K-1. The structure of biosurfactants produced by Pseudomonas aeruginosa 4K-1 was studied.
Analyses by silicic acid chromatography, thin layer chromatography, nuclear magnetic resonance spectroscopy showed these biosurfactants to be rhamnosyl-rhamnosyl-b-hydroxy-decanoyl-b-hydroxydecanoic acid (R1) and rhamnosyl-b-hydroxydecanoyl-b-hydroxydecanoic acid (R2). R1 and R2 reduced the surface tension of water to 35 mN/m and 29 mN/m, respectively.
The critical micelle concentration of R1 and R2 were 15 mg/L and 95 mg/L, respectively.
The optimal cultural conditions in 3 L fermentor were:
temperature 30℃, surface aeration with a rate of 1.5 vvm, agitation speed 600 rpm, working volume 1 L. Emulsifying ability of rhamnolipids was influenced by concentration and pH value.
In this study, strains with excellent de-emulsifying ability toward rhamnolipid,kerosene,water emulsion was isolated. The de-emulsifying ability of strain 3-11 was t1/2 = 0.1 hrs. Characterization of strain 3-11 showed de-emulsifying properties is due to cell surface. De-emulsifying ability of cells were resistant to pentane but were reduced by chloroform-
methanol extraction. The heat stability of de-emulsifier was good. The de-emulsifying ability of strain 3-11 was influenced by the amount of added de-emulsifier, biosurfactant concentration and pH value of emulsion.
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