Extraction and chemical characterization of polysaccharides from a Microcystis water-bloom in Lake Dianchi

Abstract

为了研究水华微囊藻多糖及其对水体化学和生态特性的影响,以去离子水、pH5的缓冲液和pH9.2的缓冲液为提取液,分别在4℃和80℃条件下从滇池水华微囊藻中提取多糖,并对其所提多糖部分化学特征进行分析.结果表明pH9.2的缓冲液所提多糖总得率最高,为2.25%;pH5的磷酸盐缓冲液所提多糖总得率最低,为0.383%.溶解性分析表明,不同提取液所提多糖在所试验的几种溶剂中表现为不溶、分散或部分溶解,未能找到将多塘完全溶解的溶剂.气相色谱和气-质联用分析表明,不同提取液所提多糖都含有中性单糖鼠李糖、阿拉伯糖、甘露糖、葡萄糖、半乳糖和一个未知糖.硫酸-咔唑法分析显示不同提取液所提多糖含有糖醛酸.电感耦合等离子光谱显示去离子水4℃条件下所提多糖含有很高的金属元素钙和镁,分别为2.15%和0.4%.初步研究显示,水华微囊藻多糖为酸性杂多糖,低溶解性显示在自然水体中它易形成多糖颗粒,有较高含量的金属元素说明它会影响到这些金属元素在滇池中的溶解、沉积、生物利用和循环,特别是钙和镁.;The aim of this paper is to study the polysaccharide of the native water-bloom cyanobacterium Microcystisspp. and its effect on chemical and ecological properties of aquatic environments.Polysaccharides from the water-bloom cyanobacterium Microcystis spp. of Lake Dianchi were extracted with deionized water, pH5 and pH9.2 bufferat 4*C and 80*C.Partial chemical charactristics of extracted polysaccharides was investigated. The results showedthat pH 9.2 buffer got the highest yield that was 2.25%.The lowest yield was 0. 383% with pH5 buffer. The solubility test indicated that polysaccharides extracted by various methods were insoluble, partly solubilized or dispersedin the examined solvents.The monosaccharide composition analysis with GC and GC-MS indicated the extracted polysaccharides contained rhamnose, arabinose, mannose, galactose, glucose and one unknown sugar. The sulfuricacid carbazole method showed the presentation of uronic acid in the extracted polysaccharides.The metal contentwas determined with inductively coupled plasma quantometer. The polysaccharide extracted with deionized water at4*C was found to contain high concentration of Ca and Mg, which was 2.15% and 0.4%,respectively. Preliminary study indicated that the polysaccharide from Microcystis spp.was acidic heterogeneous polysaccharides. The lowsolubility of the polysaccharide showed it may form transparent exopolymer panicles easily in natural water. Thehigh metal-binding capability of the polysaccharide showed it may influence the solubilization,precipitation, bioavailability, and cycling of metals in aquatic environments, especially Ca and Mg.