The excessive use of synthetic preservatives poses significant threats to food safety and human health. This study systematically investigated the genetic characteristics of the Limosilactobacillus fermentum (L. fermentum) z-6 strain, the antibacterial properties of the bacteriocin-like substance (FC) it produces, and its mechanism of action. The results demonstrated that this bacteriocin-like substance exhibited remarkable antimicrobial activity and exceptional stability, maintaining high activity across a broad pH range (4.0–8.0) and withstanding heat treatment at 100 °C and UV irradiation, indicating robust environmental adaptability. Its proteinaceous nature was confirmed by its detection below 1 kDa on Tricine-SDS-PAGE and its inactivation by trypsin and pepsin. The FC showed broad-spectrum inhibition against foodborne pathogens, including Salmonella enterica serovar Typhimurium, E. coli, A. baumannii, S. aureus, P. mirabilis and L. monocytogenes. Mechanistic investigation demonstrated that the FC exerts antibacterial effects primarily through membrane disruption, as evidenced by a live-dead staining assay confirming significantly enhanced permeability in Salmonella enterica serovar Typhimurium, and scanning electron microscopy revealing distinct pore formation on bacterial surfaces. It is speculated that the FC produced by z-6, due to its excellent properties and outstanding antibacterial performance, could potentially serve as a natural biopreservative.

Research has demonstrated that the presence of synthetic preservatives tends to disrupt the balance of the gut microbiota, thereby posing a significant threat to food safety and human health. The present study investigates the antibacterial activity of a novel bacteriocin-like produced by Latilactobacillus sakei (L. sakei) against Escherichia coli (E. coli), as well as its mechanism of action. This study aims to validate the significant antibacterial effect of bacteriocin-like YY-1 produced by L. sakei W-1 through dialysis combined with Tricine-SDS-PAGE analysis, and to determine its molecular weight. The results of the study indicate that the molecular weight of the bacteriocin-like is less than 2.7 kDa. Moreover, this bacteriocin-like YY-1 exhibits broad-spectrum antimicrobial properties, demonstrating antibacterial activity against E. coli, S. Typhimurium, A. baumannii, P. mirabilis, S. aureus, L. monocytogenes. Furthermore, bacteriocin-like YY-1 exhibits optimal antibacterial activity at a pH of 4.0, with its activity gradually diminishing as pH increases. It is completely inactivated by trypsin treatment, while papain and proteinase K treatments significantly reduce its antibacterial activity. Additionally, this bacteriocin-like YY-1 has been demonstrated to inhibit the growth of E. coli and disrupt its normal development. The Viable/Necrotic Cell Stain and SEM observations confirmed that the bacteriocin-like compound induces cell death by forming distinct pores through the disruption of the cell membrane’s structural integrity. In summary, YY-1—a bacteriocin-like substance characterised by its low molecular weight (<2.7 kDa), broad-spectrum activity, and pore-forming mechanism—is a highly promising natural alternative to synthetic preservatives, capable of mitigating the damage caused by chemical additives to the gut microbiota.