Preparation of sodium alginate-coated microencapsulated phage vB_SalP_SE29 and evaluation of its therapeutic effect on <i>Salmonella</i> enteritidis infection

<i>Salmonella</i> is a common gram-negative bacterium widely distributed in nature, as well as in the intestines of humans and animals, and serves as a typical representative of foodborne pathogens. Due to the increasingly prominent issue of its multidrug resistance, phage therapy has garnered extensive attention as a potential alternative. However, when administered orally, phages are readily inactivated by gastric acid, leading to a significant reduction in phage titer. As a biopolymer with excellent biocompatibility, low cost, and low toxicity, sodium alginate can form a gel through cross-linking with Ca²⁺ ions at room temperature. The preparation of microencapsulated phages effectively protects phages from gastric acid damage, thereby enhancing their antibacterial efficacy. Evaluation of relevant biological characteristics has demonstrated that microencapsulated phages significantly improve their survival ability in the gastrointestinal environment. <i>In vivo</i> studies have further confirmed the good efficacy and safety of these microencapsulated phages in the treatment of rat enteritis.