The Optimization Of Fermentation Conditions Of Sacs-Producers And Purification Of BS Produced By Bacillus Sp. SAC-11

Biosurfactant is a new type of surfactant which developed in recent years. Besides reducing surface tension as synthesized surfactants, Biosurfactant has superior properties, such as low toxicity, readily biodegradable, good ecological compatibility features etc. With the rapid development of biotechnology and related techniques, Biosurfactants not only in traditional industries will gradually replace chemical surfactants and may exceed the scope of application of traditional surfactants, playing a significant role in pharmacological effects of antibacterial, antiviral, antitumor, and immune function.In this study, a wild biosurfactant producing strain SAC-11was mutated by UV irradiation to obtain the strain SAC-2-02which increasing the surfactant production by38.43%than the original strain under the same conditions. After a series of optimization work of fermentation conditions, we determined the best carbon and nitrogen sources for bacterial fermentation of glucose and inorganic ammonium salt, C/N ratio is20/3, Carbon source concentration is60g/L. Under these conditions, the96h fermentation broth lipopeptide production is1.55g/L. Effects on biosurfactant production of other culture conditions, in addition to medium composition, such as ventilation, incubation temperature, initial pH, inoculum size, and ionic strength were studied by orthogonal experiments, the best theoretical combination of conditions were obtained:200rpm,28℃, initial pH7.0, inoculum size3%and sodium chloride3%. Under the former conditions, the biosurfactant production can reach1.87g/L,2.8times higher than SAC-11in ordinary mineral salts medium. The production is generally higher than generally reported in the lipopeptide surfactant productions.We also extracted the lipopeptide surfactant produced by strain SAC-11by acid precipitation, organic extraction and double column chromatography purification. Full-band UV scanning results of the collection component showed that the surfactant samples have no UV absorption properties. Samples eluted by HPLC with ELSD detector showing four consecutive elution peak. Changing the mobile phase liquids or elution conditions was still difficult to completely separate several peaks. The further purification of the sample may require a separation by semi-preparative high pressure liquid chromatograph.