Polysaccharide production and degradation by bacteria in food and gastrointestinal systems

本研究的长期目标是通过调节多糖的产生和降解来了解食物和胃肠道中微生物群落的动态。第一个主题将研究决定外多糖（EPS）分子质量的生物合成机制，目的是操纵EPS的大小分布，以便在食物和肠道生态系统中进行测试。环境条件对基因表达的影响将使用比较转录组学进行研究。这将有助于确定食品过程中EPS生物合成所需的最佳条件，同时提示EPS生产如何通过消化系统发生变化。基因编辑将有助于揭示蛋白质磷酸化如何调节蛋白质功能。在第二个主题中，益生菌与肠道生态系统中食源性病原体之间的相互作用将被研究。本工作将在第三个主题中提供关于病原体排除和肠道微生物群落稳定性的实验可验证的假设。在本主题中，我们将利用人类肠道微生物生态系统模拟器来评估潜在的益生菌菌株和食物病原体在胃肠道中的竞争或合作适应度。利用离散分子质量的纤维基质进行选择性富集将有利于菌株和益生元组合的评价。此外，益生菌和食物病原体在粘膜界面定殖中产生EPS的作用将被探讨。了解益生菌和乳酸菌的基因功能和调控，对于改善酸奶和奶酪发酵剂微生物的选择，以及食品安全和开发对人类健康有益的功能食品至关重要。本研究的意义在于从微生物生态学的角度了解食物结构和成分如何影响消化。饮食在微生物群落组成和活动中起着至关重要的作用，因此了解食品配方如何影响这一生态系统将有助于提高食品质量。有了这些知识，更有效地靶向益生元成分将有可能实现对肠道微生物群代谢活性的预期影响，并预防食源性感染。培养专业知识，根据微生物群组成预测对特定食物的反应，有可能开辟个性化饮食方法的前景。这项研究可以导致新型食品、功能性食品和补充剂的生产，以及通过食物更好地了解肠道微生物群落的调节。对于工业来说，研究结果可以应用于开发创新方法，为乳清等乳制品加工副产品增加价值，这将有助于减少食物浪费。

The long-term aim of this research is to understand the dynamics of microbial communities in food and the gastrointestinal tract through the modulation of polysaccharide production and degradation. The first theme will investigate the biosynthetic mechanisms determining the molecular mass of exopolysaccharides (EPS) with the aim of manipulating EPS size distribution for testing in food and gut ecosystems. The effect of environmental conditions on gene expression will be examined using comparative transcriptomics. This will help determine the optimal conditions necessary for EPS biosynthesis in food processes, while suggesting how EPS production may change through the digestive system. Gene editing will help show how protein phosphorylation regulates protein function. In the second theme, interactions between probiotics and foodborne pathogens in the gut ecosystem will be investigated. This work will provide experimentally testable hypotheses about pathogen exclusion and gut microbiome community stability in the third theme. In this theme, the fitness of potential probiotic strains and food pathogens for competition or cooperation in the gastrointestinal tract will be assessed using the Simulator of the Human Intestinal Microbial Ecosystem. Selective enrichment using fibre substrates of discrete molecular mass will facilitate the evaluation of strains and prebiotic combinations. Furthermore, the role of EPS production by probiotics and food pathogens in colonisation of the mucosal interface will be explored. Understanding gene function and regulation in probiotic and lactic acid bacteria is essential for improving the selection of yogurt and cheese starter microorganisms, as well as for food safety and developing functional foods that have a beneficial impact on human health. The significance of this research is understanding how food structure and composition impact digestion from a microbial ecology perspective. Diet plays a crucial role in microbial community composition and activity, so comprehension of how food formulation impacts this ecosystem will help to improve food quality. With this knowledge, more effective targeting of prebiotic ingredients will be possible for attaining the desired impact on the metabolic activity of gut microbiota and preventing foodborne infections. Fostering expertise to predict responses to specific foods, depending on microbiota composition, has the potential to open up the prospect of personalised dietary approaches. This research can lead to the production of novel foods, functional foods and supplements, as well as a better understanding of gut microbe community regulation through food. For industry, the results can be applied to developing innovative ways to add value to dairy processing co-products such as whey, which will contribute to reducing food waste.