Antibacterial mechanism and preservation effect of antimicrobial peptide T1 against Listeria monocytogenes in smoked salmon.

Persistent Listeria monocytogenes contamination in foods highlights the need for safe antimicrobial agents. In this study, fermentation products derived from soybean meal inoculated with Lactobacillus paracasei FX-6 were systematically investigated. A bioactive fraction, F3, was isolated and subjected to peptidomic analysis, which identified 220 peptide sequences. Molecular docking prioritized three candidate peptides, among which T1 (GLKPGLHGFHV) exhibited the strongest antibacterial activity. Preliminary mechanistic investigations suggested that T1 caused membrane damage and intracellular component leakage, and reduced biofilm formation as well as swimming motility. Metabolomic analysis revealed significant alterations in metabolite profiles, mainly involving amino acid/nitrogen metabolism and pantothenate/CoA-related metabolism. These results suggest that T1 exerted antibacterial activity associated with membrane damage and metabolic perturbations. Furthermore, in a refrigerated smoked salmon model, T1 slowed the increase in total viable counts and delayed quality deterioration. Overall, T1 represents a promising natural antimicrobial candidate for controlling L.monocytogenes in ready-to-eat foods.