Kavitake Digambar, Devi Palanisamy Bruntha, Singh Sanjay Pratap, Shetty Prathapkumar Halady
Department of Food Science and Technology, Pondicherry University, Pondicherry 605014, India.
Department of Food Science and Technology, Pondicherry University, Pondicherry 605014, India.
Int J Biol Macromol. 2016 May;86:681-9. doi: 10.1016/j.ijbiomac.2016.01.099. Epub 2016 Feb 1.
An exopolysaccharide (EPS) producing strain PUFSTM055 isolated from Idli batter (an Indian traditional cereal-legume based fermented food) was identified as Weissella confusa KR780676. The strain was shown to produce 17.2g/L (dry weight) of EPS in 2% sucrose supplemented MRS broth and the EPS was characterized. HPTLC analysis confirmed the presence of galactose monomers, indicating the homopolysaccharide nature of EPS. Fourier-transform infrared spectroscopy and nuclear magnetic resonance analysis revealed that the EPS was found to be a novel linear galactan containing α-(1→6)-linked galactose units. Scanning electron microscopy of the EPS revealed the presence of porous and spongy starch-like granules. Topographical examination of EPS by atomic force microscopy revealed that the EPS formed densely packed mesh-like structure with irregular spherical lumps. The EPS also showed high thermal stability with a degradation temperature of 287.5 °C and melting point at 274.65 °C. EPS was semi-crystalline with crystallinity index of 0.23 and showed 100% water solubility index. These characteristics of the EPS would make it a promising hydrocolloid for food industries as bio-thickeners, stabilizers and also as an encapsulating material for delivery of food bioactive compounds. This is the first study reporting the galactan compose of the EPS from lactic acid bacteria.
从印度传统谷物豆类发酵食品印地糊中分离出的一株产胞外多糖（EPS）的菌株PUFSTM055被鉴定为孔氏魏斯氏菌KR780676。该菌株在添加2%蔗糖的MRS肉汤中可产生17.2g/L（干重）的EPS，并对其进行了表征。高效薄层层析分析证实了半乳糖单体的存在，表明EPS具有同多糖性质。傅里叶变换红外光谱和核磁共振分析表明，该EPS是一种新型的线性半乳聚糖，含有α-(1→6)连接的半乳糖单元。EPS的扫描电子显微镜观察显示存在多孔且海绵状的淀粉样颗粒。通过原子力显微镜对EPS进行形貌检查发现，EPS形成了密集堆积的网状结构，带有不规则的球形团块。该EPS还具有高热稳定性，降解温度为287.5℃，熔点为274.65℃。EPS为半结晶，结晶度指数为0.23，水溶性指数为100%。EPS的这些特性使其成为食品工业中一种有前景的水胶体，可作为生物增稠剂、稳定剂，也可作为食品生物活性化合物递送的包封材料。这是首次报道来自乳酸菌的EPS的半乳聚糖组成的研究。
