The human intestinal tract is inhabited by a tremendous number of microorganisms, which are collectively termed “the gut microbiota”. The intestinal epithelium is covered with a dense layer of mucus that prevents penetration of the gut microbiota into underlying tissues of the host. Recent studies have shown that the maturation and function of the mucus layer are strongly influenced by the gut microbiota, and alteration in the structure and function of the gut microbiota is implicated in several diseases. Because the intestinal mucus layer is at a crucial interface between microbes and their host, its breakdown leads to gut bacterial invasion that can eventually cause inflammation and infection. The mucus is composed of mucin, which is rich in glycans, and the various structures of the complex carbohydrates of mucins can select for distinct mucosa-associated bacteria that are able to bind mucin glycans, and sometimes degrade them as a nutrient source. Mucin glycans are diverse molecules, and thus mucin glycan degradation is a complex process that requires a broad range of glycan-degrading enzymes. Because of the increased recognition of the role of mucus-associated microbes in human health, how commensal bacteria degrade and use host mucin glycans has become of increased interest. This review provides an overview of the relationships between the mucin glycan of the host and gut commensal bacteria, with a focus on mucin degradation.

人类肠道内栖息着大量的微生物，这些微生物统称为“肠道菌群”。肠上皮覆盖着一层致密的粘液，可防止肠道微生物群渗透到宿主的底层组织中。最近的研究表明，粘液层的成熟和功能受到肠道微生物群的强烈影响，肠道微生物群结构和功能的改变与多种疾病有关。由于肠道粘液层位于微生物与其宿主之间的关键界面，其分解会导致肠道细菌入侵，最终导致炎症和感染。粘液由粘蛋白组成，粘蛋白富含聚糖，粘蛋白复合碳水化合物的各种结构可以选择能够结合粘蛋白聚糖的不同粘膜相关细菌，有时将其降解为营养源。粘蛋白聚糖是多种分子，因此粘蛋白聚糖降解是一个复杂的过程，需要多种聚糖降解酶。由于人们越来越认识到粘液相关微生物在人类健康中的作用，共生细菌如何降解和利用宿主粘蛋白聚糖已引起越来越多的兴趣。本综述概述了宿主的粘蛋白聚糖与肠道共生细菌之间的关系，重点是粘蛋白降解。