Fermentation And Bioactivities Of Agrobacterium Radiobacter Polysaccharide

Polysaccharides have many kinds of biological activities, such as antitumor, antivirus,anti-oxidant, and they can enhance the function of immune system, and so on. More andmore attention has been paid to study on polysccharide .In this study, theexopolysaccharide producing strain-Agrobcaterium radiobacter was selected, and theculture medium and conditions of ARPS(Agrobacterium radiobacter polysaccharide)fermentation was optimized.The progresss of isolation, purifyication of ARPS fromfermentation broth was studied. The structure of the purified ARPS was analysied . TheARPS sulfates were synthesized and the biological activity on anti-oxidant and antitumor ofARPS sulfates was discussed .The main content were as following: 1) The fitting culture medium and fermentation conditions selected by single factorsexperiment was as following: The fitting concentration of glucose was 45g?L-1; caseinhydrolysate ,10g?L-1; mixed phosphate's fitting concentration was 2.4g?L-1((NH4)2HPO4:K2HPO4=2:1 w/w); the inoculum age and inoculum size were 16h and 10%(v/v)respectively; the optimum charge quantity was 100～125ml culture medium in 500ml flask,and the tempeature 30~32℃ ; and shaker rotation speed, 180rpm; initial pH ,6.5;fermentation time was 72h. Tween80 and rap oil as surfactont could modify dissolvedoxygen in the fermentation broth and promotion ARPS production. The average productionof ARPS could reach 24.8g?L-1. 2) The crude ARPS was precipitated with volume 95% ethanol in method of ethanolprecipitation and then the protein was removed by Sevage method. The semi-purifiedARPS was purified from this product by column chromatography on Sephadex G-75. Thepurifyied of sample was identified by the Sephadex G-150, and the ultraviolet spectrumshowed that the sample was a unique, homogneous component and its relative molecularweight was 7.2×104 . II3) The result of GC showed the monosaccharide component sample was glucose.From the result of FT-IR, periodate oxidation, Smith degeradation and C-NMR analysis, 13it was concluded that ARPS has a β-(1→3)- D-linked glucopyranosyl backbone with asingleβ-D- glucopyranosyl group at O-6 . 4) Some Sulfated derivatives (S-ARPS) were prepared by chemical modification ofARPS. The derivatives were subjected to FT-IR analysis and their degrees of substitution(DS) were determined. The results of Congo red test indicated that the conformation ofARPS might have been changed after chemical modification. 5) The biological activity on anti-oxidant and antitumor of S-ARPS were studied bysome experiments in vitro. The S-ARPS could scavenge O2· - generated by theself-oxidation of pyrogallic acid, and could alleviate H2O2-induced hemolysis of RBC,partially. The derivative with a lower DS could inhibit the microsomal lipid peroxidation inthe damaged liver homogenate of mice induced by CCl4; however, the derivative with ahigher DS had comparatively obvious inhibition to HeLa cells.