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.

Li H, et al. J Vet Sci. 2025 Nov;26:e90. https://doi.org/10.4142/jvs.25103

Objective: P. mirabilis is a Gram-negative rod-shaped bacterium. In this study, the SH-8 strain of P. mirabilis was isolated from swine-derived samples, and its antibiotic resistance genes (ARGs) and transmission mechanisms were systematically characterized. Methods: The minimum inhibitory concentrations (MICs) of strain SH-8 were determined by the broth microdilution method, with genomic features analyzed through whole-genome sequencing (WGS). Results: P. mirabilis SH-8 exhibited resistance to multiple antimicrobial agents. Its genome consists of a single chromosome (3,993,987 bp; GC content 38.8%) and one plasmid. WGS identified 21 distinct ARGs in this strain, along with a class 2/1 hybrid integron. Furthermore, a heatmap analysis of resistance genes from 29 P. mirabilis isolates of diverse origins revealed a striking similarity between the resistance gene profile of SH-8 and those of other strains. Conclusions: The MDR exhibited by P. mirabilis SH-8 is primarily attributed to integron-mediated resistance gene clusters within its genome, which may pose challenges for treating opportunistic infections caused by this bacterium.