| Lipopeptide biosurfactant is a kind of green surfactant, with the characteristics of non-toxic, biodegradable and bioremediation, non-pollution, high surface activity, active stability under extreme conditions, has been widely used in many fields such as environmental protection, food processing, biomedicine, agriculture, petroleum exploit, especially the enormous potential of enhanced oil recovery by in-depth study.This study has been isolated and pured a strain QS-Y1 from produced water of Daqing Oil filed, which could significantly reduce the surface tension of fermented supernatant. The strain QS-Y1 was identified as Bacillus pumilus according to the results of physical and biochemical characteristics and molecular biological identification. Blood plate experiment and preliminary thin-layer chromatography method showed the fermented product of the strain is mainly lipid peptide compounds.The culture medium and conditions of fermentation on the strain QS-Y1 were optimized, the result showed that the optimal fermentation medium:carbon source was glucose(40g/L)and nitrogen source was sodium L-glutamate(4g/L), C/N was 10/1, and the optimal conditions of fermentation: temperature 37℃, initial pH7.5, inoculating amount12%. In the above conditions, the crude lipopetide production was more than 2 times compared with production before fermentation.Characterized by thin layer chromatography(TLC) and fourier transform infrared spectrometry(IR), the biosurfactants extracting and purifying by QS-Y1 was identified as one kind of cyclic lipopeptide. The surface activity and emulsification ability of the purified lipopetide were investigated. The result showed that critical micelle concentration was 0.05mg/mL, emulsification performance has good stability, salt tolerance was in the range of 0% to 6%, pH tolerance was in the range of 2.0 to 10.0, within 2 h under 80 ℃temperature processing surface activity was stable, the lipopetide has a certain heat-resistant. |
PDF Full Text Request