Production, Characterization And Application Of Lipopeptide Biosurfactant

Biosurfactants synthesized by microorganisms are one of natural surface-active compounds produced by microorganisms, which could be classified into six groups. Basically there are six major classes of biosurfactants:, glycolipids, lipopeptide, phospholipids, lipopolysaccharides, substituted fatty acids and neutral lipids. Like synthetic surfactants, biosurfactants can reduce the surface tensions of aqueous media. However, biosurfacants have several outstanding advantages, such as higher biodegradability, lower toxicity, higher selectivity and specific activity at extreme temperatures, pH, and salinity, and they also have higher foaming, better environmental compatibility and the ability to be synthesized from renewable feed stocks and so on.A biosurfactant-producing bacterium provided by South China Sea Institute of Oceanology was studied. The detailed conclusions were as follows:(1). The strain was classified into Bacillus sp. according to its 16S rDNA sequences and designated as Bacillus SCUT09. The surface tension is lowered to 46.2 mN/m and the emulsification in kerosene-water is 34% when glucose was used as carbon source.(2). The culture conditions of the strain were primarily optimized. The best carbon and nitrogen source are the cassava starch and beef extract, respectively. Under the conditions of 1% NaCl, pH 6.5 and 28 oC, the biomass and emulsifying ability reach the maximum values.(3). Fourier transform infrared spectroscopy and thin layer chromatography analysis revealed that SCUT09 produced lipopeptide biosurfactant in the process of metabolism. Its critical micelle concentration (CMC) was 0.2 g/L and its salt tolerance was 21% of NaCl. Also, the biosurfactant has higher stability in the pH range from 4 to 11. Also, the surface tension and the emulsifying ability remained steady after 2 h incubation at 121oC.(4). Gravity sedimentation analysis results showed that lipopeptide prepared in this study was a good kind of nano-materials dispersant. Compared to CTAB, the size of nano-ZnO particles using lipopeptide prepared in this study as dispersant is smaller by scanning electron microscopy and electron microscopy analysis.