Lemoine J, Chirat F, Wieruszeski J M, Strecker G, Favre N, Neeser J R
Université des Sciences et Techniques de Lille, Villeneuve d'Ascq, France.
Appl Environ Microbiol. 1997 Sep;63(9):3512-8. doi: 10.1128/aem.63.9.3512-3518.1997.
We investigated the structures of the exopolysaccharides (EPSs) produced by Streptococcus thermophilus SFi39 and SFi12. Both polymers were found to have molecular masses of greater than 2 x 10(6) Da. The SFi39 EPS consisted of D-glucose and D-galactose in a molar ratio of 1:1, whereas the SFi12 EPS was composed of D-galactose, L-rhamnose, and D-glucose in a molar ratio of 3:2:1. Methylation analysis of and nuclear magnetic resonance spectra recorded from the native polysaccharide, as well as oligosaccharides released by partial acid hydrolysis, allowed the complete structural determination of the SFi39 EPS, which consists of the following tetrasaccharide repeating unit: [formula: see text] Similar spectra recorded only from the native polysaccharide were sufficient to allow the structural determination of the SFi12 EPS, which consists of the following hexasaccharide repeating unit: [formula: see text] This study shows that the texturizing properties of different S. thermophilus ropy strains are based on the production of EPSs exhibiting chemical similarities but structural differences.
我们研究了嗜热链球菌SFi39和SFi12产生的胞外多糖（EPSs）的结构。发现这两种聚合物的分子量均大于2×10⁶ Da。SFi39 EPS由摩尔比为1:1的D-葡萄糖和D-半乳糖组成，而SFi12 EPS由摩尔比为3:2:1的D-半乳糖、L-鼠李糖和D-葡萄糖组成。对天然多糖以及部分酸水解释放的寡糖进行甲基化分析和核磁共振光谱记录，从而完成了SFi39 EPS的完整结构测定，其由以下四糖重复单元组成：[化学式：见原文]仅从天然多糖记录的类似光谱足以完成SFi12 EPS的结构测定，其由以下六糖重复单元组成：[化学式：见原文]本研究表明，不同嗜热链球菌黏性菌株的增稠特性基于产生具有化学相似性但结构不同的EPSs。
