Vasanthakumari Dilna Sasidharan, Harikumar Surya, Beena Divya Jayakumar, Pandey Ashok, Nampoothiri Kesavan Madhavan
Biotechnology Division, National Institute for Interdisciplinary Science and Technology (NIIST), CSIR, Trivandrum, Thiruvananthapuram, 695 019, Kerala, India.
Appl Biochem Biotechnol. 2015 May;176(2):440-53. doi: 10.1007/s12010-015-1586-2. Epub 2015 Apr 23.
A high molecular weight (3037 kDa) dextran-like polysaccharide was purified from the culture broth of a probiotic Weissella cibaria. Dry weight of the exopolysaccharides (EPS) obtained after ethanol precipitation was 6.35 g/L by using sucrose as carbon source and was further purified by phenol:chloroform:isoamyl alcohol (25:24:1) extraction and acetone precipitation to white powder with 52% recovery. Rheological characterization revealed that it has a pseudoplastic behaviour and showed a temperature tolerance of up to 280 °C in thermogravimetric analysis. Fourier transform infrared (FTIR) spectra showed the characteristic peaks of polysaccharide such as hydroxyl group, α-pyranose, asymmetrical C-H stretching vibration of methyl group and carbonyl hydrogens of D-glucopyranose. The (1)H nuclear magnetic resonance (NMR) spectrum showed resonances of hydrogen corresponding to the glucosyl residue, a repeat unit of the biopolymer. The cell viability analysis of normal L6 cells treated with the Weissella EPS showed that it is noncytotoxic even up to the 500-μg/mL level. A 0.2% (w/v) supplementation of EPS in 2% (w/v) wheat starch preparation could reduce the degree of syneresis up to 45% and up to 75% with 1% EPS.
从益生菌食窦魏斯氏菌的培养液中纯化出一种高分子量（3037 kDa）的类葡聚糖多糖。以蔗糖为碳源，经乙醇沉淀后获得的胞外多糖（EPS）干重为6.35 g/L，再通过苯酚：氯仿：异戊醇（25:24:1）萃取和丙酮沉淀进一步纯化，得到白色粉末，回收率为52%。流变学表征显示其具有假塑性行为，在热重分析中表现出高达280℃的温度耐受性。傅里叶变换红外（FTIR）光谱显示了多糖的特征峰，如羟基、α-吡喃糖、甲基的不对称C-H伸缩振动和D-葡萄糖吡喃糖的羰基氢。氢核磁共振（1H NMR）光谱显示了与葡糖基残基相对应的氢的共振信号，葡糖基残基是该生物聚合物的重复单元。用食窦魏斯氏菌EPS处理正常L6细胞的细胞活力分析表明，即使在500μg/mL水平下它也无细胞毒性。在2%（w/v）的小麦淀粉制剂中添加0.2%（w/v）的EPS可使脱水收缩程度降低高达45%，添加1%的EPS时可降低高达75%。
