Safety evaluation of Lactiplantibacillus plantarum N13: genomic, phenotypic, and toxicological assessment for probiotic applications.

Probiotics offer numerous health benefits and are increasingly incorporated into dietary supplements and food products. Rigorous safety evaluations are essential to ensure their suitability for human consumption. This study evaluates the safety profile of Lactiplantibacillus plantarum N13, isolated from traditional fermented dairy products, through genomic and phenotypic analyses. Whole-genome sequencing confirmed general length of strain N13 (containing three plasmids) is about 3,318,516 bp, GC content is 44.4% and the absence of antibiotic resistance and virulence genes. Antibiotic susceptibility tests demonstrated that N13 is sensitive to ampicillin (1 μg/ml), gentamycin (4 μg/ml), kanamycin (32 μg/ml), erythromycin (0.5 μg/ml), clindamycin (0.25 μg/ml), tetracycline (32 μg/ml), and chloramphenicol (8 μg/ml), meeting the European Food Safety Authority (EFSA) guidelines. Additionally, genome analysis confirmed that N13 lacks genes related to biogenic amine biosynthesis, indicating its low risk of biogenic amine production. Scanning electron microscopy confirmed that N13 cells exhibited typical L. plantarum morphology. Phenotypic assays demonstrated that N13 is non-hemolytic and lacks harmful enzyme activity, including α-galactosidase, β-glucuronidase, and α-mannosidase. Acute and 28-day oral toxicity tests demonstrated that N13 was well tolerated in both Immunocompetent Research mice and Sprague Dawley rats, with no observable toxic effects or adverse changes even at high doses. At the recommended dose (0.5 × 1010 CFU/kg), N13 exhibited good oral safety. These findings establish L. plantarum N13 as a safe and promising probiotic strain, paving the way for its further application in dietary and functional food products.