Bacterial Exopolysaccharides - Relationship between chemical structure, intrinsic viscosity and technofunctionality

细菌胞外多糖 - 化学结构、特性粘度和技术功能之间的关系

• 批准号: 460131094
• 负责人: Dr.-Ing. Doris Jaros
• 金额: --
• 依托单位: Institut für Chemie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/460131094?language=en
• 关键词: Bacterial; Exopolysaccharides; Relationship; between; chemical

Hydrocolloids are commonly used in various foods to improve texture and stability. The use of lactic acid bacteria, which are able to produce exopolysaccharides (EPS) during fermentation, may significantly contribute to the development of clean-label products with as few additives as possible. The homo- and heteropolysaccharides synthesized by lactic acid bacteria show a high structural heterogeneity, which results in large differences in their macromolecular characteristics and hence, in their intrinsic viscosity and technofunctional properties. In our foregoing projects, we gained knowledge on the reproducible synthesis of sufficient amounts of EPS from different Streptococcus thermophiles strains, on gentle isolation procedures without structural changes, and on the macromolecular and technofunctional properties of the EPS. In addition, the molecular structure of selected EPS was evaluated in cooperation with the Wefers group.However, because of the high structural heterogeneity of EPS from lactic acid bacteria and the multiple factors of influence, less is known about the effects of the molecular structure on the EPS technofunctionality.The aim of this project is to establish unambiguous correlations between single structural attributes (degree of branching, glycosidic linkages, molecular mass) and the intrinsic viscosity as well as the technofunctionality of selected EPS. For this purpose, selected HePS are synthesized in situ in a bioreactor and selected α-glucans are synthesized ex situ by using recombinant enzymes. Variation of synthesis conditions as well as subsequent mechanical and enzymatic modifications yield EPS samples, which differ only in one structural attribute (for example the degree of branching), but not their molecular mass. For a more detailed analysis of the structural properties of the EPS, established modern analytical approaches as well as newly developed fingerprinting methods will be used. The latter are based on the chromatographic analysis of oligosaccharides which are liberated by partial acid hydrolysis or, if possible, by specific enzymes. We expect sound knowledge on the relationship between the molecular structure and the macromolecular and technofunctional properties of EPS, which can be transfered to further EPS.

水胶体通常用于各种食品中，以改善质地和稳定性。乳酸菌在发酵过程中能够产生胞外多糖（EPS），使用乳酸菌可能会大大有助于开发具有尽可能少的添加剂的清洁标签产品。由乳酸菌合成的均多糖和杂多糖显示出高度的结构异质性，这导致它们的大分子特性存在很大差异，因此，它们的特性粘度和技术功能特性也存在很大差异。在我们的上述项目中，我们获得了关于从不同的嗜热链球菌菌株中可再现地合成足够量的EPS的知识，关于没有结构变化的温和分离程序，以及关于EPS的大分子和技术功能性质的知识。此外，与Wefers小组合作，对所选EPS的分子结构进行了评估。然而，由于乳酸菌EPS的高度结构异质性和多种因素的影响，分子结构对EPS技术功能性的影响知之甚少。本项目的目的是建立单一结构属性之间明确的相关性。（支化度、糖苷键、分子量）和特性粘度以及所选EPS的技术官能度。为此，在生物反应器中原位合成选定的HePS，并通过使用重组酶非原位合成选定的α-葡聚糖。合成条件的变化以及随后的机械和酶改性产生EPS样品，其仅在一个结构属性（例如支化度）上不同，而不是其分子量。为了更详细地分析EPS的结构特性，将使用已建立的现代分析方法以及新开发的指纹识别方法。后者是基于对低聚糖的色谱分析，低聚糖是通过部分酸水解或如果可能的话通过特定的酶释放的。我们期望对EPS的分子结构与大分子和技术功能性质之间的关系有充分的了解，这可以转移到进一步的EPS。