Study On Optimizaiton Of Fermentation Production Pocess And Variety Of Products Of Gellan Gum

The gellan gum is one of the most promising microbial polysaccharides in recentyears, widely used in food, pharmacy, petroleum, chemical industry and other fields,this article has major research on the following areas:（1）Choose the original laboratory strains as starting strain, through UV and NTGmutation process,get a high and stable strains,named P-8. The yield of gellan gum couldarrive at14.2g/L,raised by264%.Besides, the strain which can be good use of organicnitrogen source and can be preserved in phosphate buffer for half a year. the carbonsource utilization of the strain was wide, the optimum growth temperature28-30℃, themost suitable culture condiitons of initial pH was6.5~7.（2）By one single factor experiment and RSM，it makes sure the culturecondiitons and culture medium. A medium containing42.9g/L of sucrose,6.9g/L ofalkaline hydrolysis of soya flour,1.8g/Lof k2HPO4,1.0g/Lof kH2PO4,1g/Lof MgSO4,0.02g/Lof MnSO4,0.01g/L FeSO4was found to be suitable for gellan gum production.Under the culture condiitons of initial pH7.0,80mL medium in500mL shaken flask,200rpm rotary rate and culture temperature28℃,the optimal result could be attained.After the optiimzation,the yield of crude gellan gum could be increased by60.5％.（3）The gellan gum was prepared in an50L fermentor. It is indicated that thegeneral agitation form can not satisfy their high oxygen needs in fermentation process,the final residual sugar was9.02g/L,the viscosity of broth was about5300cp,the yield ofgellan gum was17.9g/L after the femrentation for70h, the1m3fermentor indicatedthat when changed the forms and the intensity of mix, the yield of gellan guminfemrentor was26.2g/L which was equality of that in shaken flask,the final residualsugar was2.02g/L,the viscosity of broth was about9800cp.(4) The gel temperature and the gel strength of gellan gum increased firstly thendecreased with ion concentration increased. The gel temperature and the gel strength ofgellan gum was lower when the ion was much more or less. Higher concentration ofgellan gum could result in higer gel temperature of gellan gum and more strengthenedgel-gel. No synergistic effect is found for Ca2+and K+、Na+to induce gellan gel.(5) The initial conditions of gellan gum extraction: fermentation liquid diluted10times,9000rpm,15min, the gellan gum bacteria precipitated in large amounts,the effectof the alkaline protease was the best. Protein removal rate of it was up to93.56%, lighttransmission rate increased from47.62%to90.85%, then received high-acyl transparent gellan gum.Low-acyl transparent gellan gum received after enzymatic deacetylation, theoptimum processing conditions was PH10,90℃, bath time20min, gel strength was900g.