芽孢杆菌胞外多糖的结构初步分析

Study on Structure of Exopolyseccharide of the Bacillus

从筛选自新疆罗布泊沙漠的1株芽孢杆菌的发酵滤液中分离得到胞外多糖EPSⅠ和EPSⅡ,其中EPSⅠ为主要成分,占总糖的89.5%,EPSⅠ为糖蛋白,其分子质量为96.292ku,多糖含量为93.79%,蛋白含量为5.62%,不含糖醛酸,是由D-N-乙酰葡萄糖胺,D-木糖和D-甘露糖构成,它们的摩尔比例是2.36∶0.98∶1.75。EPSⅠ为β型吡喃糖,经高碘酸氧化和Smith降解,EPSⅠ中含有(1→),(1→3)和(1→4)糖苷键,且(1→)和(1→4)糖苷键的比例为1∶24.05,其中的糖肽是O-糖苷键。

The exopolysaccharides EPS Ⅰ and EPS Ⅱ from fermentation filtrate of Bacillus obtained from LUOBUPO Desert were studied. As the main component, EPS Ⅰ was accounted for 89.5% of total sugar. This paper mainly reported the physical and chemical properties and primary structure of EPS Ⅰ. The results showed that EPS I was protein-bound polysaccharide. The average molecular weight of EPS Ⅰ was 96. 292 KDa and polysaccharide content was 93.79 %, 5.62 % for protein, but had no uronic acid. It was composed of D-N-acetylglucosamine, D-xylose and D-mannose in the molar ratio of 2.36 ： 0.98 ： 1.75. The monosaccharides of EPS Ⅰ were β-pyranose. Analysis by periodate oxidation and Smith degradation indicated that EPS was composed of （1→）, （1→3） and （1→4） glycosidic linkages and the ratio of （1→） and （1→4） was 1：24.05. EPS Ⅰ was expressed O-linked glycoprotein.