红球菌HX-2所产胞外多糖的特性和对Cu2+的吸附

Adsorption of Cu2+ by exopolysaccharide from Rhodococcus sp. HX-2

摘要:

【背景】目前，微生物所产胞外多糖(exopolysaccharide，EPS)的理化性质及其在重金属吸附中的应用受到了广泛关注。【目的】研究红球菌HX-2所产胞外多糖的理化性质，并探究其对重金属的吸附情况。【方法】使用离子交换和凝胶色谱分离法对胞外多糖粗品进行纯化；利用苯酚硫酸法测胞外多糖中糖含量；用Bradford试剂盒检测胞外多糖中蛋白含量；使用甲醇萃取法检测胞外多糖中脂质含量；用高效液相色谱(high performance liquid chromatography，HPLC)法分析胞外多糖中单糖组成；用扫描电镜(scanning electron microscopy，SEM)法观察多糖表面形态；通过等温吸附模型和动力学模型探究胞外多糖对重金属的吸附效果。【结果】测得胞外多糖主要成分EPS-G-1中总糖含量为78.43%，蛋白含量为8.31%，脂质含量为8.22%；纯化后胞外多糖中单糖组成为葡萄糖、甘露糖、半乳糖、葡萄糖醛酸和岩藻糖，质量比为27.31:26.67:24.83:15.85:4.80；通过等温吸附模型拟合得到HX-2所产胞外多糖对Cu2+的最大吸附量为144.93 mg/g。【结论】红球菌HX-2所产胞外多糖对水体中Cu2+具有良好的吸附作用，可用于工业废水中重金属离子的处理。

Abstract:

[Background] At present, the physicochemical properties of exopolysaccharide (EPS) produced by microorganisms and their application in heavy metal adsorption have been widely concerned. [Objective] The physicochemical properties of exopolysaccharide produced by Rhodococcus sp. HX-2 was studied and the adsorption of heavy metals by exopolysaccharide was investigated. [Methods] The crude exopolysaccharide was purified by ion exchange and gel chromatography. Sugar content was measured by phenol-sulfuric acid method. Protein content was determined by using the Bradford kit. Lipid content was measured by methanol extraction method. Monosaccharide composition was analyzed by high performance liquid chromatography (HPLC). The surface morphology was observed by scanning electron microscopy (SEM). The adsorption effect of exopolysaccharide on heavy metals was studied by isothermal adsorption model and kinetic model. [Results] The total sugar content, protein content and lipid content of the EPS-G-1 produced by HX-2 were 78.43%, 8.31% and 8.22%, respectively. After purification, the monosaccharide of exopolysaccharide was composed of glucose, mannose, galactose, glucuronic acid and fucose; the mass ratio was 27.31:26.67:24.83:15.85:4.80, respectively. The maximum adsorption capacity of exopolysaccharide produced by HX-2 to Cu2+ was 144.93 mg/g by isothermal adsorption model fitting. [Conclusion] The exopolysaccharide produced by HX-2 has favourable adsorption effect on Cu2+ in water and can be used for the treatment of heavy metal ions in industrial wastewater.