Fermentation Optimization And Characterization Of Surfactants Produced By Bacillus Amyloliquefaciens

Biosurfactants are compounds composed of hydrophilic and hydrophobic compounds that permit distribution in two fluid phases with different polarities.Biosurfactants are characterized by ecological acceptability and degradability.A major obstacle on the way of wide-scale industrial application of biosurfactant is the high production cost coupled with less production rate as compared to commercially available synthetic surfactants.Therefore,the production cost is required to be more competitive with synthetic surfactants,which requires optimization of fermentation conditions,including the possibility of using no-cost or low-cost waste as a carbon source.In order to solve this problem,this study screened the strains that can produce surfactants from soil,focused on the potential of producing biosurfactants from agricultural and industrial wastes and the characterization of biosurfactants.The results are as follows:(1)In this experiment,a high-yield surfactant producing strain PG-1 was isolated from soil by blood plate method and oil drainage circle method.It was identified as Bacillus amyloliquefaciens by morphology and 16 S r RNA analysis.(2)The production of biosurfactant is related to the culture conditions.The culture conditions were optimized and the orthogonal experiment was designed.The results showed that in the medium composed of 15 g mannitol,5 g yeast extract and 3 g potassium dihydrogen phosphate at 37 ℃,150 r/ min and 60 h fermentation,the yield was 2.75 g/L,which increased by175.6%.(3)The influence factors of strain PG-1 using agricultural and industrial wastes to produce value-added biosurfactants in solid-state fermentation were investigated.Sesame dregs and peanut powder were found efficient and selected as major substrates for surfact in production.The resultsof Plackette Burman design indicated that water content,fermentation time and peanut powder were the significant variables identified in the screen of nine total variables.The Boxebehnken design determines the optimal values of the three salient variables.The most ideal growth conditions for obtaining the best surfactant output are 4.41 g peanut powder,5 g sesame residue,2.5%(w/w)mannitol,2%(w/w)yeast extract,p H 6.0,inoculation the amount is5%,the temperature is 33 ℃,the fermentation is 70.8 h,and the water content is 60%(v/w).The experimental value is 19.56 mg/gds,which is 1.45 times the unoptimized value.(4)The properties of biosurfactants separated by HCl precipitation and solvent extraction were studied.Preliminary chemical characterization revealed the anionic properties of the biosurfactant.The biosurfactant was characterized by thin layer chromatography(TLC)and fourier transform infrared spectroscopy(FTIR).The biosurfactant also demonstrated stability during exposure to high temperatures(up to 120 degrees C for 120 min),high salinity(20%Na Cl)and a wide p H range(3-11),and its critical micelle concentration was determined as 30mg/L.When surfactant was added to MSM medium with the final concentration of 30 mg/L,the oil degradation rate was increased by 7.44%.