Beijing Laboratory of Food Quality and Safety, Beijing Technology and Business University, Beijing, China; School of Biological and Agricultural Engineering, Jilin University, Changchun, China.
Beijing Laboratory of Food Quality and Safety, Beijing Technology and Business University, Beijing, China.
Carbohydr Polym. 2015 Jul 10;125:16-25. doi: 10.1016/j.carbpol.2015.03.003. Epub 2015 Mar 9.
An exopolysaccharide (EPS)-producing strain YW11 isolated from Tibet Kefir was identified as Lactobacillus plantarum, and the strain was shown to produce 90 mgL(-1) of EPS when grown in a semi-defined medium. The molecular mass of the EPS was 1.1 × 10(5)Da. The EPS was composed of glucose and galactose in a molar ratio of 2.71:1, with possible presence of N-acetylated sugar residues in the polysaccharide as confirmed by NMR spectroscopy. Rheological studies showed that the EPS had higher viscosity in skim milk, at lower temperature, or at acidic pH. The viscous nature of the EPS was confirmed by observation with scanning electron microscopy that demonstrated a highly branched and porous structure of the polysaccharide. The atomic force microscopy of the EPS further revealed presence of many spherical lumps, facilitating binding with water in aqueous solution. The EPS had a higher degradation temperature (287.7°C), suggesting high thermal stability of the EPS.
一株从西藏酸乳中分离得到的产胞外多糖（EPS）的菌株 YW11 被鉴定为植物乳杆菌，该菌株在半确定培养基中生长时可产生 90mg/L 的 EPS。EPS 的分子量为 1.1×10(5)Da。EPS 由葡萄糖和半乳糖组成，摩尔比为 2.71:1，通过 NMR 光谱证实多糖中可能存在 N-乙酰化糖残基。流变学研究表明，在脱脂牛奶中、在较低温度下或在酸性 pH 值下，EPS 具有更高的粘度。扫描电子显微镜观察证实了 EPS 的粘性，表明多糖具有高度分支和多孔的结构。EPS 的原子力显微镜进一步显示存在许多球形块状物，有利于在水溶液中与水结合。EPS 的降解温度较高（287.7°C），表明 EPS 具有较高的热稳定性。
