Screening And Optimization Of Culture Medium Of Surfactant Strains And Studying Of Quantity

Compared with chemical surfactant, biosurfactant has obtained international attention because of its environment friendly and broad application potential. Therefore, the works of exploitation of bio-surfactant microorganism resources, improving their yield in fermentation solution, and studying of surfactant quantifying have extensive biological and economic significance.In this paper, twelve strains which could produce bio-surfactant were screened by designing a selective cultural medium and all of them could reduce the surface tension of the fermentation solution from (68±0.2) mN/m to 40 mN/m. After being identified, most of the strains were bacteria and others were epiphyte. Two of the strains which were identified as Burkholderia gladioli and Absidia orchidi showed the best surface-active and were chose for culturing optimization by using orthogonal experimental method. Under the optimized fermentation conditions, bio-surfactant productions of the two strains have increased 17 and 13 times, respectively. What's more, bio-surfactant produced by Burkholderia gladioli was lipopeptid determined by the methods of Methylene blue-chloroform test and thin layer chromatography with its critical micelle concentration of 20~25 mg/L in distilled water.For various bio-surfactants discovered, Rhamnolipid was well studied. H2SO4-Anthrone analysis method, L-cysteine-H2SO4 method and phenol-H2SO4 method were compared in the present paper, and the influence factors were also considered. The results showed that H2SO4-Anthrone analysis method was better than the others and its optimal reaction condition was obtained. The influence to the quantitative analysis of rhamnolipid from the residual glucose and the top clean liquid layer in the ferment solution could be ignored. But the influence from the bacterial body and the middle layer of the ferment solution reached a certain degree. Thus, the bacterial body should be removed before measuring. However, the influence from the middle layer of the ferment solution could be avoided by making a standard curve which was made by using a rhamnose mixed with the middle layer ferment solution.Many adsorption isotherm indicates correlation between surfactant density and surface/interfacial tension or adsorptive capacity is very strong, but correlation between surfactant density and surface tension and dilution multiple has not been reported and therefore was studied in this paper. The resuld showed that the simulated curve of multiple-surface tension value of the n+1 discretization data point and the...