Whole-Genomic and Functional Characterization of Lactiplantibacillus plantarum CLPX21 as Potent Probiotic Candidate

Lactic acid bacteria (LAB) are regarded as promising probiotics with multiple beneficial properties for humans' and animals' health. In this study, ten LAB isolates were screened and Lactiplantibacillus plantarum (L. plantarum) CLPX21 was selected as a candidate strain with its probiotic potential based on in vitro screening of antimicrobial activity and environmental stress tolerance, including its resistance to acidic environments and bile salts. This strain displayed adhesion capacity with an auto-aggregation rate of 47.15% at 24 h, co-aggregation rates above 67% with pathogenic bacteria, and an ability to adhere to IPEC-J2 cells (6.37%). CLPX21 showed broad-spectrum antimicrobial activity against common foodborne pathogens including Escherichia coli (E. coli), Salmonella, and Staphylococcus aureus. In addition, CLPX21 inhibited E. coli biofilm formation. Furthermore, CLPX21 significantly suppressed E. coli-induced inflammatory cytokine production in mouse peritoneal macrophages. Importantly, CLPX21 did not exhibit hemolytic activity. Genomic analysis further revealed that the CLPX21 genome encoded multiple functional genes and gene clusters, including biosynthesis of bacteriocins and secondary metabolites associated with antimicrobial and antioxidant functions, which provide a genetic basis for its beneficial phenotypic characteristics. In conclusion, L. plantarum CLPX21 displays probiotic properties with potent antimicrobial and anti-inflammatory activities, representing a promising candidate strain for applications in the food and health industries.