Tannic acid-integrated alginate microbeads for enhanced protection of probiotics against antibiotic killing

Orally administered antibiotics can disrupt gut microbiota and lead to intestinal disorders. Although probiotics are commonly used to restore gut homeostasis, their efficacy is compromised in the presence of antibiotics. Here, we present edible probiotic microbeads (E@AlgTA) that are resistant to antibiotic drug treatment, simply by co-encapsulating Escherichia coli Nissle 1917 (EcN) and tannic acid (TA) in alginate (Alg) microgels. TA, a plant-derived polyphenolic compound, forms nanoprecipitates with various antibiotics through molecular complexation, reducing their free concentration and thereby enhancing the viability of probiotic cells. Compared to unencapsulated EcN, E@AlgTA demonstrates significantly improved viability in the presence of gentamicin treatment, a broad-spectrum bactericidal drug used in the clinic. Besides, the pH-sensitive Alg shell provides efficient protection for the encapsulated cells in simulated gastric and intestinal fluids. This approach offers a promising strategy to deliver probiotics in harsh environments, potentially applicable in treating antibiotic-associated gastrointestinal disorders.