Details

The species Enterococcus lactis is closely related to E. faecium and is known for its beneficial and probiotic effects. In this study, strain RRS4 was isolated from Raphanus sativus Linn. and identified based on both phenotypic and genotypic characteristics. Strain RRS4 exhibited cell viability in environments with 2-8% NaCl, pH ranging from 4 to 9, and temperatures between 4°C and 45°C. Through comprehensive genomic analysis, strain RRS4 was confirmed to be E. lactis. E. lactis RRS4 demonstrated inhibitory effects against Vancomycin-resistant E. faecalis JCM 5803. Safety assessments via in silico methods, including KEGG annotation, indicated the absence of virulent and undesirable genes in E. lactis RRS4. VirulenceFinder analysis aligned virulence-related genes with those from three strains of E. lactis and four strains of E. faecium. While antibiotic resistance genes were found to be conserved, they did not correlate with key pathogenicity traits. Furthermore, safety evaluations highlighted that E. lactis RRS4 is generally safe, despite the presence of genes associated with antibiotic resistance. Lastly, we propose guidelines for assessing the safety of microbial strains using whole-genome analysis. These findings represent advancements in probiotic research.