Exopolysaccharide production and degradation by lactic acid and probiotic bacteria: a functional approach to improve their applications in food and health

胞外多糖（EPS）是一种碳水化合物聚合物，可以改善食物质地并影响肠道微生物群落。本研究计划的目的是了解结构特征如何决定EPS的功能特性。通过操纵组成和分子量，我们将能够研究这些参数对食物中EPS功能特性的影响，在胃肠道微生物群模型中以及与人体粘膜和免疫细胞的相互作用中。然而，我们所研究的菌株之间的EPS产量差异很大，表明可能存在调节和降解差异。该研究计划的第一个主题是阐明基因和蛋白质调控的机制，以了解胞外多糖的产生如何与环境信号和代谢协调。第二个主题是研究决定EPS分子量的机制，目的是操纵EPS尺寸分布，用于乳制品系统中的测试以及与人类细胞的相互作用。使用酶将产生具有较低分子量的EPS。这将有助于开发能够影响发酵乳制品流变学特性的增粘成分。第三个主题是研究EPS与肠道微生物群（病原体和益生菌）和宿主细胞（粘膜和免疫调节细胞）的相互作用，以了解功能机制和聚合物结构对这些相互作用的影响。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，以及防止食品腐败和开发对人类健康有益的功能性食品和成分至关重要。这项研究将刺激加拿大乳制品和功能性食品行业的创新，以改善乳制品加工和开发功能性食品成分。2013年，加拿大生产了7800万升牛奶，价值157亿加元的加拿大牛奶和乳制品占制造食品和饮料总价值的16%。乳制品加工业在加拿大465家乳制品加工企业中雇用了近23，000名员工。加拿大有超过750家专门从事功能性食品和天然健康产品的公司，创造了超过110亿美元的收入，约占全球销售额的2.5%。鉴于消费者对健康和保健相关产品的巨大需求，预计未来将继续增长。这些部门需要知识基础和人员方面的支助。根据加拿大统计局2013年的一项调查，科学研发、技术或工程人员被确定为功能性食品企业实现战略目标的关键能力，同时代表了空缺职位的最大需求。

Exopolysaccharides (EPS) are carbohydrate polymers that can improve food texture and influence the microbial community of the intestine. The aim of this research program is to understand how the structural characteristics determine the functional properties of EPS. By manipulating composition and molecular mass, we will be able to investigate the effect of these parameters on the functional properties of EPS in food, in models of the gastrointestinal microbiota and in interactions with human mucosal and immune cells. However, EPS yield varies greatly among the strains we have studied, indicating possible differences in regulation and degradation. The first theme of this research program is to elucidate the mechanisms of gene and protein regulation to understand how exopolysaccharide production is coordinated by environmental signals and metabolism. The second theme is to investigate the mechanisms determining the molecular mass of EPS with the aim of manipulating EPS size distribution for testing in dairy food systems and in interactions with human cells. EPS with lower molecular mass will be produced using enzymes. This will contribute to the development of viscosifying ingredients that can influence the rheological properties of fermented milk products. The third theme is to investigate the interactions of EPS with the gut microbiota (pathogens and probiotic bacteria) and with host cells (mucosal and immune modulating cells) in order to comprehend functional mechanisms and the impact of polymer structure on these interactions. Understanding gene function and regulation in probiotic and lactic acid bacteria is essential for improving yogurt and cheese starter microorganisms, as well as for preventing food spoilage and developing functional foods and ingredients that have a beneficial impact on human health. This research will stimulate innovation by the Canadian dairy and functional food industries to improve dairy processing and develop functional food ingredients. In 2013, Canada produced 78 million hectolitres of milk and Canadian milk and dairy products worth $15.7 billion represent 16% of the total value of manufactured food and beverages. The dairy processing industry employs close to 23,000 people across Canada in 465 dairy processing establishments. There are over 750 Canadian companies specialized in functional foods and natural health products, generating more than $11 billion in revenues, which is about 2.5% of global sales. Continued future growth is projected, given the significant consumer demand for products related to health and wellness. These sectors require support in knowledge base and personnel. From a Statistics Canada survey in 2013, scientific R&D, technical or engineering staff were identified as the critical competencies for reaching strategic goals by functional food establishments while representing the greatest needs in unfilled positions.