Department of Home & Health Sciences, Allama Iqbal Open University Islamabad, Pakistan.
Int J Biol Macromol. 2013 Aug;59:377-83. doi: 10.1016/j.ijbiomac.2013.04.075. Epub 2013 May 7.
This project was designed to study the coculturing affect of exopolysaccharide (EPS) producing strains Lactobacillus kefiranofaciens (L.k) ZW3, with non EPS producing strains L. bulgaricus (L.b) and Streptococcus thermophilus (S.t) in three different combinations: L.k+L.b, L.k+S.t, and L.k+L.b+S.t. FTIR analysis revealed presence of strong stretch in regions of 3400, 2900 and 1647cm(-1) which is characteristic of a typical polysaccharide. Co-cultured EPSs were composed of glucose, galactose, arabinose and xylose; and their sugar compositions were different from ZW3 polysaccharide that was mainly composed of gluco-galactan. Peak temperature for L.k+L.b, L.k+S.t, L.k+S.t+L.b and ZW3 polymers were 90.59, 87.61, 95.18 and 97.38°C, respectively. Thermal analysis revealed degradation temperature of 326.44, 294.6, 296.7 and 299.62°C for L.k+L.b, L.k+S.t, L.k+S.t+L.b and ZW3 polymers, respectively. SEM and AFM analysis divulged that three cocultured EPSs had different surface morphology than ZW3 polymer. Since co-cultured polymers have different structure than the polymer produced exclusively by EPS producing strain, it can be safely concluded from the study that co-culturing can be one way to change the structure of polymers. Coculturing of L. kefiranofaciens with non-EPS producing strains resulted in yoghurt with increased viscosity and delayed syneresis.
本项目旨在研究胞外多糖（EPS）产生菌株嗜酸乳杆菌（L.k）ZW3 与非 EPS 产生菌株保加利亚乳杆菌（L.b）和嗜热链球菌（S.t）在三种不同组合中的共培养影响：L.k+L.b、L.k+S.t 和 L.k+L.b+S.t。FTIR 分析表明，在 3400、2900 和 1647cm(-1) 区域存在强拉伸，这是典型多糖的特征。共培养的 EPS 由葡萄糖、半乳糖、阿拉伯糖和木糖组成；它们的糖组成与主要由葡糖半乳糖组成的 ZW3 多糖不同。L.k+L.b、L.k+S.t、L.k+S.t+L.b 和 ZW3 聚合物的峰值温度分别为 90.59、87.61、95.18 和 97.38°C。热分析表明，L.k+L.b、L.k+S.t、L.k+S.t+L.b 和 ZW3 聚合物的降解温度分别为 326.44、294.6、296.7 和 299.62°C。SEM 和 AFM 分析表明，三种共培养的 EPS 具有与 ZW3 聚合物不同的表面形态。由于共培养的聚合物的结构与仅由 EPS 产生菌株产生的聚合物不同，因此可以从研究中得出结论，共培养可以是改变聚合物结构的一种方式。嗜酸乳杆菌与非 EPS 产生菌株的共培养导致酸奶的粘度增加和滞后收缩延迟。
