Submerged Culture Of Mushroom And Polysaccharide Structure Modification

Lentinan(LNT) contain important medicinal ingredients,which play significant healthy protection role in anti-tumor,immunity modulation and anticoagulation.LNT is an important source for foods and medicines.In this paper,we studied the fermentation conditions of LNT produced by lentinus edodes during submerged fermentation,and researched the optimal reaction conditions of the phosphorylation of LNT and its chelate with Zinc ion,then characterized the physicochemical properties of the reacted and unreacted LNT.The major conclusions are as follows:1.The fermentation conditions of crude ceto-polycose produced by lentinus edodes during submerged fermentation were determined.The result was as follow:crude ecto-polycose at 8th day and biomass at 10th day reached the biggest output;the optimizated carbon source was glucose,the optimizated nitrogen source was peptone.Glucose,peptone and NaCl were the major factors in medium that significantly affected the yields of crude ecto-polycose during submerged fermentation.The result indicated when glucose,peptone and NaCl were 25 g/L,16 g/L,0.8g/L, crude ecto-polycose was the highest,arriving at 0.8460g/100mL.2.The preparation of phosphorylated LNT was studied and the graft quantity of phosphate and viscosity in the modified LNT were investigated.The single element and orthogonal test showed the optimum phosphorylated LNT reaction conditions were as follows:8%mix of phosphorylation reagent,temperature 80℃,time 5h,and pH value 8.0.Under these conditions,the graft quantity of phosphate was 7.771%,and the viscosity of phosphorylated LNT did not decline significantly compared to the control.3.The optimum reaction conditions of Zn²⁺ chelated LNT were as follows:25%mass ratio of ZnSO₄·7H₂O,temperature 90℃,time 4h,and pH value 7.0.Under these conditions,the graft quantity of Zn²⁺ in LNT was 9.7363%.4.The physicochemical properties of LNT produced in submerged fermentation and the modified LNT were characterized.The results showed that the crude ecto-polycose, phosphorylated LNT and Zn²⁺ chelated LNT were all water-soluble,and all of them contain reducing sugar,monosaccharide or disaccharide,but lack starch.The quantity of pure polysaccharide and uronic acid were 86.25-88.40%and 4.298-4.952%,respectively.Compare to the LNT without reaction,the quantity of pure polysaccharide and uronic acid in phosphorylated LNT and Zn²⁺ chelated LNT changed slightly.It indicated that when LNT was modified,its structure was hardly destroyed.5.The experiment indicated that LNT has antioxidant activity.The antioxidant activity of phosphorylated and Zn²⁺ chelated LNT were higher than those LNT without modified reaction. And the antialexin activity of phosphorylated LNT was higher than that LNT without modified reaction.