Antimicrobial effects and metabolomics analysis of cell-free supernatant produced by Pediococcus acidilactici LWX 401 isolated from Yunnan traditional pickles

Foodborne pathogens pose a significant risk to human health via the food chain. Here, we evaluated the antibacterial effects of cell-free supernatant (CFS) of Pediococcus acidilactici (P. acidilactici) LWX 401 isolated from food-grade Chinese traditional pickles and found that it exhibited broad antibacterial activity against multidrug-resistant gram-negative Escherichia coli (E. coli) O157:H7 and yogurt-derived gram-positive Staphylococcus aureus (S. aureus), with inhibition zone sizes of 23.10 +/- 0.80 and 20.53 +/- 0.07 mm, respectively (all P < 0.001 compared with the controls). Moreover, the CFS exhibited strong thermostability and pH tolerance and was capable of inhibiting the formation of biofilms of these foodborne pathogens. Notably, the LWX 401 CFS inhibited both E. coli O157:H7 and S. aureus contamination in milk samples under different storage temperatures (4 degrees C, 25 degrees C, and 35 degrees C), with considerable bacterial reduction by 1-7 log CFU/mL compared with untreated controls. Additionally, the potential antibacterial metabolites (VIP >1, adjusted P < 0.05, and fold-change >2; n = 56) were identified in the LWX 401 CFS by UHPLC-QE-MS metabolomic analysis, and these metabolites were mostly lipids (25.73%) and organic acids (23.30%). Our results provide insights for the development of bio-preservatives against foodborne pathogens in the milk industry.