Metal–Phenolic Nano Protective Layer Coating Enterococcus mundtii PL86 Prevents IBD by Promoting Lactobacillus to Enhance the Sulfur Relay Pathway

Oral administration of probiotics is an effective strategy for mitigating inflammatory bowel disease (IBD) progression. However, gastrointestinal challenges significantly hinder probiotic colonization. In this study, Enterococcus mundtii PL86, known for its antibacterial properties, is isolated through comparative screening of fecal microorganisms from healthy and diarrheal piglets across multiple farms. A protective nanocoating (Fe-TA-GN) composed of Iron (III), tannic acid (TA), and β-glucan (GN) is engineered to encapsulate PL86, enhancing its resistance to enzymatic degradation, bile salts, and acidic conditions in vitro. Murine trials show that Fe-TA-GN-PL86 effectively prevents IBD symptoms induced by Enterotoxigenic Escherichia coli (ETEC) modulated TNF-α, IL-6, and IL-10 expression, alleviating intestinal mucosal damage and inflammation. Microbiome and metabolome analysis shows that Fe-TA-GN-PL86 administration significantly increases the abundance of Lactobacillus in intestinal microbiota, L-cysteine in intestinal metabolites is positively correlation with Lactobacillus and influences the sulfur transport system obtained by enrichment. This mechanism strengthened intestinal mucosa defense against pathogenic invasion, reducing IBD-associated diarrhea. In conclusion, these findings elucidate the critical molecular mechanisms of Enterococcus mundtii PL86 in modulating intestinal microbiota and reinforcing mucosal barrier, while advancing probiotic delivery systems for IBD prevention and microbiota-targeted therapeutic development.