Study On Preparation And Application Of A New Biosurfacant

Biosurfactants are natural amphiphilic compounds that are produced by microorganism and had the structure of hydrophilic and hydrophobic groups. They have a certain surface activity, as well as its own advantages: innocuity, biodegradable easily; higher foaming, well demulsification; higher inhibition on bacteria, fungi and viruses; it can be used as natural additives because of no sensitized and digestible, people are paying more and more attention to them in fine chemical industry, food industry, medicine and agriculture.This paper mainly studied comprehensively on screening of strain that produced biosurfactants,identification of the strain,optimization of the fermentation conditions,physiological and biochemical nature of the products,purification of the products,application of the antibacterial activity and other aspects.Screening superiority strain BS01 that producing biosurfactants by using the determination methods of ring surface tension,oil discharge activity and emulsification. The fermentation fluid of strain BS01 had well foaming,higher emulsion capacity and oil discharge activity, strain BS01 was identified as Bacillus subtilis by colony morphology,culture characteristies and identification of physiological and biochemical.Separation and extraction from fermentation fluid of strain BS01 initially, the experiments results showed that the biosurfactants were lipopeptide substances, the oil-water emulsion capacity can still reach to 80% after 15d, it had a wide pH range and emulsification had little change in the pH range of 2-8, the biosurfactants had strong tolerance on temperature that the surface active still remained after 120℃high temperature treatment。The fermentation process that strain BS01 produced biosurfactant was optimizeda by dopted response surface method to determine the culture conditions based on the single-factor test: initial pH was 7.06, the culture temperature was 37.5℃, inoculum was 3.89%, shaking speed was 158.94r/min.The lipopeptide biosurfactants had a highly effective antibacterial spectrum on agricultural pathogenic fungi and human pathogenic bacteria, it had a strong adaptability on temperature, salt concentration and pH. Lipopeptide biosurfactant extracted from strain BS01 fermentation of had better preservation effect on decay of fruits and vegetables slowly. The corrosion rate was 78.5%, with good application on fruit and vegetable preservation.