Antimicrobial activity and mechanism of novel postbiotics against foodborne pathogens

Postbiotics are effective in preserving food and preventing spoilage, but their antimicrobial activities and mechanisms are still largely unknown. This study aims to investigate the antimicrobial activity, mechanism of action, and efficacy components of a novel postbiotic (from Bacillus amyloliquefaciens J and Lactobacillus plantarum SN4) that we have recently developed. The water extract of this postbiotics (PWE) exhibited strong bactericidal effects against a wide range of pathogens such as Escherichia coli, Staphylococcus aureus, and Salmonella typhimurium. PWE significantly disrupted bacterial cell membranes and consequently leaked cell contents and induced bacterial genomic DNA degradation. In addition, PWE can prevent E. coli from infesting the host by inhibiting its adhesive action. Organic acids, particularly lactic acid (378 ± 4.1 mg/g) and acetic acid (40.8 ± 2.2 mg/g) were identified as the key antibacterial components in PWE. Furthermore, we demonstrated that PWE was safe for mammalian cells and exhibited high stability under enzymatic degradation and heat treatment. In conclusion, our data revealed the great potential of the novel postbiotics in combating microbial infections and suggesting new strategies for food preservation in the food industry. • Novel postbiotics (PWE) exerts antibacterial activity against three foodborne pathogens. • PWE significantly disrupts cell membranes and damages the genomic DNA of pathogenic bacteria. • Lactic acid and acetic acid are identified as the key antibacterial components in PWE. • PWE is highly safe for mammalian cells and is stable under enzymic and heat treatment.