The Technology Of Fermentation And Enzymatic Degradation For Bioacitve Exo-polysaccharide From Schizophyllum Commune

Schizophyllan (SPG), which is a kind of fungal polysaccharide with high molecular weight, has the specific structure composed ofβ-(1, 3) main-chain andβ-(1, 6) branched-chain, and has high immune activity and anti-tumor activity. SPG can be isolated from S. commune and from the pure fermentation culture of S. commune. Different species of S. commune produce different molecular weight of SPG. Now, SPG with Mw 4.5×105 Da has been developed as a clinical anti-tumor additive.In this study (paper), the fermentation conditions and culture medium of Schizophyllum commune for producing SPG were optimized, and the pretreatment process of the fermentation culture was optimized, as well as, the way to isolating SPG with the specific molecular weight was explored. The results were as follows:(1) The pretreatment process of the fermentation culture was established to obtain high yield SPG. The fermentation culture was extracted twice (2 h each time)with boiling water bath. The water extractives and liquid fermentation culture were combined to isolate SPG. The SPG yield isolated by this way was improved 55% comparing to that isolated from non-pretreatment fermentation culture. Discoloration effects of polysaccharide dialyzed with dialysis bags by ethanol was good, and the highest retention rate of SPG was 92.85%.(2) A simple and effective determination method of polysaccharide content, Congo red staining method. By this method, the crude polysaccharide content was determined as 86.28% in this study.(3) Optimized the fermentation conditions and culture medium :28-30℃, pH 5.6, broth content is 100 ml in 250-ml Erlenmeyer flask, culture period was 168 h and shaking speed was 180 rpm. The yield of SPG was 10.80 g/L under the conditions.(4) The optimization fermentation medium optimized through single factor analytical method and response surface analytical method was that 1 L fermentation medium contained 12% glucose, 1% yeast extract, 0.2% peptone, 0.2% K2HPO4, 0.1% MgSO4?7H2O, 0.92% CMC-Na, 0.209% citric acid, 1.45 mg folic acid and 0.4 mg NAA. The SPG yield of S. commune cultured with this fermentation medium could reach 13.37 g/L.(5) The study data of S. commune cultured in Erlenmeyer flask was validated through culturing S. commune in 10 L fermentor. And the results showed that the average yield of SPG could reach 22.09 g/L under 0.5 m3/h ventilation at 200 rpm with the optimization fermentation medium of (4).(6) Established the technology of enzymatic degradation for bioactive polysaccharide: the pretreatment fermentation culture by dialysis bags was diluted 5-fold, and 1 ml of the diluted culture was added with 1μlβ-glucanase and incubated for 5 min at 28℃. SPG with Mw 4.47×105 Da could be isolated from the enzyme-treated culture and the SPG content was 63.20%.