Whole-genome sequencing and in vitro characterization of two lactic acid bacteria isolates with potent antimicrobial activity from fermented vegetables

Lactic acid bacteria (LAB) exist in various sources including the gastrointestinal tract and fermented foods, and are considered beneficial for animal and human health. In this study, two LAB strains Lactiplantibacillus plantarum CLPX16 and Weissella cibaria CLPX19 were isolated from fermented vegetables and characterized for probiotic properties through whole-genome sequencing and in vitro functional assays. Genomic analysis revealed that although homologs of several virulence-related genes were detected in both strains, they exhibited low sequence identities and lacked classical virulence gene determinants such as toxins, secretion systems, or invasion proteins. In contrast, both strains harbored beneficial genes including bacteriocin biosynthesis clusters and secondary metabolite gene clusters associated with antimicrobial and antioxidant properties. Both strains exhibited strong tolerance to acidic conditions with high survival rates at pH 2.0, 3.0, and 4.0, as well as tolerance to bile salts. Moreover, both strains exhibited robust acid production capacity, inducing a rapid pH decline during 0-36 h of incubation. In addition, both strains exhibited notable antioxidative activity, nitrite degradation capacity, and adhesion capacity. Importantly, CLPX16 and CLPX19 exhibited potent antimicrobial activity against foodborne pathogens including Staphylococcus aureus, Escherichia coli, and Salmonella enterica. Notably, these strains lacked hemolytic activity and showed low risk of horizontal transfer of antibiotic resistance genes. In conclusion, CLPX16 and CLPX19 demonstrate promising probiotic potential and represent candidate strains for application in food and health industries.