Safety Evaluation of Weissella paramesenteroides MW-142 Isolated From Traditional Fermented Mulberry Wine

Weissella paramesenteroides MW-142 is a lactic acid bacterium (LAB) isolated from traditional fermented mulberry wine, with prior optimization of its high-density cultivation indicating industrial potential. To ensure its safe application in food and pharmaceuticals, this study comprehensively evaluated the biosafety of MW-142 through phenotypic and genomic analyses. An acute oral toxicity test in mice (20.0 mL/kg body weight, corresponding to 9.5 × 10⁸ CFU/mL) showed no signs of poisoning or mortality over 14 days, with histopathological analysis confirming normal organ morphology. Hemolysis tests revealed no hemolytic zones (γ-hemolysis). Biochemical assays for harmful metabolites (indole, nitroreductase, amino acid decarboxylase, and azoreductase) were negative. Genomic screening using the Virulence Factor Database (VFDB) and the Comprehensive Antibiotic Resistance Database (CARD) identified 83 putative virulence-associated genes; however, over half shared < 50% sequence similarity with known determinants, and no classical toxin genes (e.g., hemolysins, enterotoxins) were found. Only intrinsic, low-risk antibiotic resistance genes were identified, and these were not associated with mobile genetic elements. These findings establish MW-142 as a safe candidate for industrial applications, providing a scientific basis for its further development as a probiotic or biopreservative.