Exploring the anti-Listeria monocytogenes mechanisms of the postbiotics derived from Ligilactobacillus salivarius LSA-6 and its biopreservative effects on Inner Mongolian cheese

Food contamination caused by Listeria monocytogenes has been a major concern worldwide, and postbiotics derived from lactic acid bacteria are promising in controlling foodborne pathogens, while the antibacterial effects and mechanisms are still largely unclear. This study aimed to investigate the anti - L. monocytogenes activity and mechanisms of the postbiotics derived from Ligilactobacillus salivarius LSA-6 (Postbio-LSA-6), and its potential application in Inner Mongolian cheese preservation. Results showed Postbio-LSA-6 exhibited efficient anti - L. monocytogenes activity, the minimal inhibitory concentration (MIC) was 4 mg/mL. Postbio-LSA-6 at 2MIC could significantly disrupt the bacterial membrane integrity, the membrane-damaged cells percentage increased to 49.6 %, leading to the intercellular materials leakage and cell death. Besides, Postbio-LSA-6 at 2MIC could induce the oxidative stress in bacterial cells, the membrane-fluorescence cells percentage increased to 46 %, resulting in lipid peroxidation. Untargeted metabolomics analysis showed organic acids and fatty acids such as erythronic acid, citric acid, 2-hydroxybutyric acid, and oleic acid were identified as the main differentially expressed metabolites in Postbio-LSA-6. Furthermore, Postbio-LSA-6 could effectively maintain the moisture content and pH stability, reduce the color and texture alterations, and extend the shelf life of cheese samples by suppressing microbial proliferation and lipid oxidation. These results offered new insights on the antibacterial activities of postbiotics against foodborne pathogens, and provided a low-cost, label-friendly biopreservation strategy for local dairy products preservation.