Preliminary Studies on the Isolation, Purification and Physicochemical Properties of Extracellular Acidic Polysaccharides from <i>Microcystic aeruginosa</i> var. <i>major</i>

本实验的目的是提取和纯化铜绿微囊藻(Microcystic aeruginosa var. major)胞外带酸性基团的多糖,为综合利用爆发的水华提供一定的理论依据.采用 pH 8.0、80℃的热水抽提铜绿微囊藻的胞外多糖.经充分脱蛋白、脱色后用 DEAE-纤维素(DE-52)作离子交换柱层析,分离出其中不被 DE-52吸附和被吸附的两种组分.取后者上 sephadexG-150柱进一步分离得到两种分子量不同的酸性多糖(EAPS Ⅰ和 EAPSⅡ),质量比为1.92:1,经 HPLC测定 EAPS Ⅰ均分子量为7.01×10⁴D,EAPSⅡ均分子量为4.21×10⁴D.经测定,它们各带有不同含量的酸性基团:EAPS Ⅰ糖醛酸含量为10.74%, SO₄^2-含量为44.44μg/mg,EAPSⅡ糖醛酸含量为7.08%,SO₄^2-含量为9.08μg/mg.EAPSⅠ单糖组成为:9.6549%D(+)木糖,19.2522% D-果糖,71.0930%葡萄糖;EAPSⅡ单糖组成为:6.4065%D(+)木糖,18.0016%D-果糖,75.5919%葡萄糖.;Hie occurrence of harmful microcystis blooms in eutrophic water bodies is a worid wide problem. Microcystis usually forms mucilaginous sheath surrounding colony which floats on the surface of water body. Hie mucilaginous sheath was mainly composed of polysaccharides. To provide theoretical evidences in multipurpose use of Microcystis bloom, the aim of this study was to isolate and purify acidic polysaccharides from Microcystic aeruginosa var. major cultares. Extracellular acidic polysaccharides were extracted by hot water at 80℃ and pH 8.0 from M. aeruginosa var. major in the study. After being deproteinized and decolored, the neutral and acidic polysaccharides were pooled from the elutes of DEAE-52 gel column. Then, the acidic polysaccharides were further loaded on Sephadex G-150 column, two fractions (fraction Ⅰ, EAPS Ⅰ; fraction Ⅱ, EAPS Ⅱ) of different molecular weights were obtained, Their mass ratio is 1.92:1. Detected by HPLC, the results showed that the average molecular weight of EAPS Ⅰ was 7.01×10⁴ tand the mean molecular weight of EAPS Ⅱ was 4.21×10⁴. EAPS Ⅰ was consisted of 10.74% uronic acid, the content of SO₄^2- was 44.44 μg/mg; EAPSⅡ was consisted 7.08% uronic acid, the content of SO₄^2- was 9.08μg/mg. The monosaccharide constitutions of EAPS Ⅰ were 9.6549% D (+) xylose, 19.2522% D-fructose, 71.0930% glucose. TTie monosaccharide constitutions of EAPS Ⅱ were 6.4065%, D (+) xylose, 18.0016% D-fructose, 75.5919% glucose.