Comparative genomics and untargeted metabolomics analysis of dairy-derived Lacticaseibacillus rhamnosus strains and their potential applications in dairy fermentation

Lacticaseibacillus rhamnosus (L. rhamnosus) is widely recognized as a probiotic species. This study explored the genomics and metabolomics of 4 L. rhamnosus strains (Probio-M9, ProSci-109, IMAU13187, and IMAU99155) in dairy environments, and their potential application in dairy fermentation. Results showed high similarity in genome size, GC content, and genetic relationship among the strains. However, they differ in carbohydrate and AA metabolism. Both ProSci-109 and Probio-M9 can metabolize lactose and hydrolyze milk proteins. The strains generated compounds that improve the taste and sensory aspects of dairy products, including 2-phenylethanol, phenyllactic acid, and glutamic acid, and health-beneficial compounds, such as genistein, daidzein, and trihydroxyflavone, along with peptides. Incorporating ProSci-109 significantly increased poststorage viscosity without disrupting gelation kinetics during fermentation. Notably, pH and titratable acidity remained consistent between the ProSci-109 and control groups after 21-d storage period, suggesting that ProSci-109 could be a valuable addition to starter cultures for fermented milk production.