Probiotic characterization of Ligilactobacillus murinus ZQL11 isolated from healthy dog feces

Currently, canine-derived probiotics, especially those specifically developed for dogs, remain relatively scarce. Our study aimed to isolate bacterial strains from the feces of healthy dogs and to screen for those with excellent probiotic properties. A total of 12 strains were isolated and identified through morphological observation and 16 S rRNA gene sequencing. These strains were systematically evaluated for key probiotic characteristics, including tolerance to simulated gastrointestinal conditions, antimicrobial activity, adhesion-related properties, and overall safety. Among them, Ligilactobacillus murinus ZQL11 (ZQL11) demonstrated the most promising probiotic profile. This strain exhibited strong acid tolerance, with a survival rate of 75.23% after 3 h at pH 2.0, and notable bile salt resistance, maintaining 78.86% survival after 4 h in 0.3% bile salts. Antibacterial assays revealed significant inhibitory effects against Escherichia coli, Salmonella enterica, and Staphylococcus aureus. Adhesion-related evaluations showed high cell surface hydrophobicity together with strong auto-aggregation and co-aggregation abilities. In vivo safety assessment in mice showed that ZQL11 did not induce detectable toxicity or adverse effects; no significant differences were observed in routine blood parameters between the ZQL11-treated and control groups, and no obvious histopathological lesions were found in the major organs. In summary, ZQL11 exhibited favorable tolerance, adhesion-related properties, safety, and antibacterial activity, suggesting its potential for further application in animal microecological preparation.