Lacticaseibacillus rhamnosus OF44 with Potent Antimicrobial Activity: Evidence from the Complete Genome and Phenotypic Analysis.

Lacticaseibacillus rhamnosus is extensively studied, with some strains widely applied for enhancing human health. Complete genome analysis is crucial for the functional exploration of probiotics. This study aimed to investigate the potential of L. rhamnosus OF44 (OF44) to promote human health through complete genome and phenotypic analysis. The complete genome sequence of OF44 was 2,978,769 bp, with 2791 CDSs and an average GC content of 47%. In vitro experiments demonstrated that OF44 had a broad carbon source fermentation capacity. Resistance gene analysis and simulated digestion tests confirmed the favorable tolerance of OF44 under harsh conditions, suggesting its potential as an oral supplement. OF44 possessed various potential genes related to bioactive substances with antimicrobial activity, such as antimicrobial peptides, lactic acid, hydrogen peroxide, and exopolysaccharides, most of which were detected in vitro. Further, OF44 exhibited significant growth inhibition capacities against pathogens from the gut, vagina, skin, and mouth, likely due to high co-aggregation with pathogens, multiple antimicrobial peptide clusters, and adhesin gene clusters. Additionally, oral administration of OF44 was found to reduce the pH and inflammation levels in the vaginal microenvironment of rats with bacterial vaginosis. Therefore, OF44 exhibited probiotic properties in improving reproductive tract bacterial infections by modulating vaginal microbiota balance and inhibiting pathogen growth. In summary, this study provided a new perspective on the application of OF44 as a supplement in the food and pharmaceutical fields.