Food-Grade Metal–Phenolic Network and Polysaccharide Microencapsulation Enhances the In Vivo Anti-Colitic Efficacy of Lactiplantibacillus plantarum B112

Background/Objectives: Probiotic therapy for inflammatory bowel disease (IBD) has a persistent practical obstacle: most cells given by mouth die before they reach the colon. Methods: To keep L. plantarum (Lactiplantibacillus plantarum) B112 alive along this route, we first assembled a gallic acid–ferric ion metal–phenolic network (MPN) around the bacteria and then added an outer layer of sodium alginate or hyaluronic acid; the resulting microcapsules, assembled entirely from food-grade materials, were evaluated in mice during a 7-day dextran sulfate sodium (DSS) course. Results: Among all formulations, the alginate-coated ones (LLM@SA; 108 colony-forming units (CFU)/day for 5 days) were the most effective. Body weight loss slowed, the disease activity index fell, and colon shortening was less severe than in the DSS controls. In colonic tissue, interleukin (IL)-1β, IL-6, tumor necrosis factor (TNF)-α, and myeloperoxidase decreased, IL-10 increased, the mucus layer recovered, and mucin 2 (MUC2), zonula occludens-1 (ZO-1), and occludin were maintained; serum lipopolysaccharide (LPS), D-lactic acid (D-LA), and diamine oxidase (DAO) also dropped. 16S rRNA gene sequencing revealed a partial correction of DSS-induced dysbiosis, with Akkermansia and Alistipes enriched while Escherichia-Shigella and Enterococcus were suppressed. Conclusions: A plausible interpretation is that the double coating improved the survival of B112 during gastrointestinal transit and allowed more viable cells to reach the large intestine, where the strain could modulate immunity, barrier integrity, and the microbiota. However, viable B112 was not directly quantified in fecal or intestinal samples, and coating-only control groups were not included, so this mechanism remains inferential and a contribution of the coating materials themselves cannot be excluded. The data therefore support further preclinical investigation of this microencapsulation strategy, assembled from food-compatible materials, as a nutritional approach in models of IBD.