Select Pullulan High-yield Strain And Study On It’s Fermentation Characteristics

Pullulan is a major polysaccharide produced by strain of Aureobasidium pullulans. Pullulan is safe, non-toxic, heat-resistant, salt-resistant, acid-resistant, it has strong plasticity, good film, oxygen barrier capability, season and climate has little effect, and other unique physical, chemical and biological characteristics. It is widely used in food packaging, pharmaceutical manufacturing, fruit and seafood, fresh, cosmetics industry, agriculture seed protection and tobacco manufacturing industry. Many scientists concern on it, it is a versatility and new biological product with great development value and application prospect.Accompanied by the production of pullulan, Aureobasidium pullulans secrete a black or dark green pigment, which seriously affect separation and purification of pullulan.This experiment researched Aureobasidium pullulans by ethyl methane sulphonate (Ethyl methanesulfonate, EMS) and UV mutagenesis, designed to fundamentally solve the pigment problems, and also increase the yield of pullulan, and provide basic research data and the reference method for the industrial production of pullulan. A Pullulan mutant strain UV60with low pigment content and high pullulan of22. lg/L was obtained by EMS (final concentration was0.2mol/L, reaction time was40-60min) and UV (30W,irradiation, distance was30cm, irradiation time was1.5-2.5min)mutagen. pullulan’production increased by29.42%.For studying growth and pullulan’production in fermentation medium, through doing single factor and orthogonal array design on C/N ratio of culture medium and culture medium, an optimum culture medium had been obtained with sugar50.0g/L, yeast extrac1g/L, NaCl2g/L, MgSO40.3g/L, K2HPO43.0g/L,(NH4)2SO40.7g/. The pullulan was27.24g/LFor studying different trace elements and their concentration on the production of pullulan, through doing single factor and orthogonal array design on CrCl3, ZnSO4, MnSO4and C5H11NO2Se, an optimum combination was CrCl30.5mg/L, ZnSO40.15mg/L, MnSO40.2mg/L, C5H11NO2Se12.5mg/L.The pullulan was27.24g/L.Finally the fermentation process of Aureobasidium pullulans with fermentation tanks were researched. Through studing stirring speed and pH control methods of bacterial fermentation, finalize the stirring speed of250r/min constant pH of6.5, The pullulan was maximum under this condition.