Bio-functional Levilactobacillus brevis strains of feline origin: the potential probiotic food adjunct for companion animals.

Although autochthonous probiotic application is considered standard for the host-specific environment, the allochthonous probiotics also deliver valuable physiological or therapeutic benefits during their transit period before being eliminated naturally. This study evaluated the probiotic and bio-functional attributes of seven zoo feline-derived Levilactobacillus brevis strains for their potential application in companion animals or functional food industry. In vitro methods were employed to assess their survival under simulated gastrointestinal tract (GIT) conditions, safety profiles (hemolytic activity, DNase activity, and antibiotic susceptibility), and bio-functional potential (antimicrobial, antioxidant, and hypocholesterolemic activities). All strains exhibited high survival in the presence of lysozyme (69.0-96.7%), gastric juice (60.7-91.3%), and bile concentrations (up to 78.4-92.2% at 1.8% bile). The isolates displayed strong hydrophobicity (41.7-85.5%) and auto-aggregation properties (29.8-75.2%), and no signs of toxicity (non-hemolytic and DNase negative). Significant variations were noticed among strains with reference to their probiotic and bio-functional properties (p < 0.05). Furthermore, the strains secreted antioxidant metabolites capable of scavenging 2, 2-diphenyl-1-picrylhydrazyl (62-72%), hydroxyl (54-65%), and superoxide (57-69%) radicals. Among selected isolates, strain Lb I (L. brevis MZ400640) demonstrated the strongest antagonistic activity against both Gram-positive and Gram-negative pathogens. The bile salt hydrolase (BSH) gene was conserved across all seven isolates, confirming their ability to deconjugate major mammalian bile salts, sodium glycoholate and taurocholate. Out of the 14 parameters evaluated, strain Lb VII (L. brevis MW450245) exhibited most robust overall performance highlighting the potential of Lb VII as a functional probiotic feed additive to promote health and manage hypercholesterolemia in companion animals.