The Fermentation Dynamics,Purification And The Modification Of Exopolysaccharide PS202

In this dissertation, we have studied the fermentation dynamics ,the purification and the sulfation of PS202,besides this, we also studied the structure of both PS202 and sulfated PS202(PS202S). The main results are as followings:1.we studied the fermentation course of PS202, the fermentation kinetic parameters of biomass, polysaccharide and sucrose consumption were calculated by applying the Logistic and Luedeking-Piret Equation respectively. By comparing the experimental data with the models applying MATLAB,three models were testified and could describe the fermentation course well.2.After the Membrane filtration and other purification process, the average molecular of PS202 is about 12,6000 by HPLC. From IR,¹HNMR, ¹³CNMR, a deduction was given that PS202 was composed of D-glucose and the presence of carboxyl linkage in the polymer areβ-(1-6)grycosidic,and the branch is composed of pyruvic acid. Periodate oxidation experiment showed that glycosidic bond (1, 6): [ (1, 2),(1, 4)]: (1, 3) =5.00: 3.75: 1 (mol) DEAE-Sepharose Fast Flow ion exchange chromatography was used to purity the polysaccharides. 4 different kind of EPS were obtained.3.Chlorsulfonic acid -Pyridine method was used to make the PS202S.We also groped the sulfation conditions. The optimized sulfation condition were: reaction temperature was 45℃, chlorsulfonic acid : pyridine was 1, reaction time was 6h. Under this condition ,we obtained PS202S with Ds1.68. The IR NMR results showed that we successed to add the sulfate to PS202.We can speculate that PS202S was composed of D-glucose and the presence of carboxyl linkage in the polyment areβ-(1-6) andβ-(1-3)glycosidic,and the branch is composed of pyruvic acid...