The early microbial colonization of the gastrointestinal tract can have long-term impacts on development and health. Keystone species, including Bacteroides spp., are prominent in early life and play crucial roles in maintaining the structure of the intestinal ecosystem. However, the process by which a resilient community is curated during early life remains inadequately understood. Here, we show that a single sialidase, NanH, in Bacteroides fragilis mediates stable occupancy of the intestinal mucosa in early life and regulates a commensal colonization program. This program is triggered by sialylated glycans, including those found in human milk oligosaccharides and intestinal mucus. NanH is required for vertical transmission from dams to pups and promotes B. fragilis dominance during early life. Furthermore, NanH facilitates commensal resilience and recovery after antibiotic treatment in a defined microbial community. Collectively, our study reveals a co-evolutionary mechanism between the host and microbiota mediated through host-derived glycans to promote stable colonization.

胃肠道的早期微生物定植会对发育和健康产生长期影响。包括拟杆菌在内的关键物种在生命早期很突出，在维持肠道生态系统的结构中发挥着至关重要的作用。然而，人们对早年塑造有复原力的社区的过程仍知之甚少。在这里，我们发现脆弱拟杆菌中的单一唾液酸酶 NanH介导生命早期肠粘膜的稳定占据并调节共生定植程序。该程序由唾液酸化聚糖触发，包括人乳寡糖和肠粘液中发现的唾液酸化聚糖。NanH 是从母鼠到幼崽的垂直传播所必需的，并促进脆弱拟杆菌在生命早期占据主导地位。此外，NanH 有助于特定微生物群落在抗生素治疗后的共生恢复力和恢复。总的来说，我们的研究揭示了宿主和微生物群之间通过宿主衍生的聚糖介导的共同进化机制，以促进稳定的定植。