Fermentation And Bioactivities Of Streptomyces Polysacciharide

Streptomyce is famous for its capability of producing many kinds of antibiotics, Few report related to SPS (Streptomyces Polysaccharide) has been found so far. In this study, the exopolysaccharide producing strain-Stretomyces was selected from thousands of strains, and the progresss of isolation, purifyication of SPS from fermentation broth was studied. The structure of the purifyied SPS was analysed; the culture medium and conditions of SPSfermentation was optimized; and the biological activity of SPS on antibacterium, anti-oxidant and antitumor was discussed. The main content were as following: 1) Isolation, purification and structure of SPS (1) The crude SPS was precipitated with volume 95% ethanol in method of ethanol precipitation and then the protein was removed by Savage method and salted out by (NH4)2SO4, respectively, followed by being dialysed by dialysis tubing. The purified SPS was purified from this product by column chromatography on Sephadex G-75. (2) From the ultraviolet spectrum of SPS, the sample of SPS did not have protein and nucleic acid,the purity of the sample was 96.2% by Sulfuric acid-anthrone coloremetric methd. (3) SPS was analyzed for infrared spectra by FT-IR infrared spectrometer scanning from 4800to 700cm-1.The results showed that SPS had typical infrared spectra of polysaccharide, and the monosaccharides was linked with β-glycoside bond. (4) The results of GC-MS showed that the sample was made of mannose, glucose, galactose, which was 2:1:1 by proportion. (5) Its molecular weight was 68000dal determined by Sephadex G-150 chromatography . (6) periodate oxidation, Smith degeradation showed that SPS has (1 →3) and (1→6)-linked glycoside bond. 2) The optimal culture medium selected by single factor experiment was as following :Glucose and amylum were the optimal carbon source and the fitting concentration was 3% and 4% respectively; soybean meal and (NH₄)₂SO₄ were the optimal nitrogen source and the fitting concentration were 4%and 0.8% respectively; salts such as MgSO4(0.1%), K2HPO4( 0.4%),NaCl(1.0%) could promote the SPS yield; CaCO3 (0.03%) is necessary to keep pH in range of 7.2⁷.6; the initial pH was 7.4⁷.6. The fermentation condition obtained by orthogonal experiment was as following: the inoculum age and inoculum size were 48h and 10%(v/v) respectively; the optimum charge quantity was 50ml culture medium in 500ml flask, and the optimum temperature 30 ℃; and shaker rotation speed 200rpm; fermentation time was 168h. The average production of SPS could reach 25.5g/L. 3) The biological activity on antibacterium,anti-oxidant and antitumor of SPS was studied. The results showed that SPS could inhibit the growth of bacterium including Cercospora beticola, Magnaporthe grisea, Escherichia coli, Bacillus Subtilis, Pseudomonas aeruginosa and Staphylococcus aureus; And SPS could scavenge O2·-generated by the self-oxidation of pyrogallic acid, alleviate H2O2-induced hemolysis of RBC, inhibit the microsomal lipid peroxidation in the damaged liver homogenate of mice induced by CCl4; Further more, SPS had obvious inhibition on S180 in the body .