The revelation of high-yield amino acids and probiotic characteristics of an intestinal Lacticaseibacillus rhamnosus X9C17.

With the popularization of probiotic products, tapping high-quality probiotics is crucial. Therefore, in this study, Lacticaseibacillus rhamnosus (X9C17) was selected from a pool of 54 isolates for its remarkable ability to survive in simulated gastrointestinal fluid (Gastric juice: 81.08 %, intestinal juice: 48 %), after which its probiotic characteristics were evaluated. Strain X9C17 exhibits strong antibacterial properties, hydrophobicity, self-aggregation ability and significant antioxidant capacity, and it can produce essential amino acids, including glycine and proline. Therefore, the experimental results show that X9C17 has potential probiotic function. Metabolomics methods were used to study the changes in metabolites in X9C17 fermented milk. The hydroxycinnamic acid, L-3-phenyllactic acid, amino acids and multiple vitamins accumulated in the fermented milk, played a positive role in the probiotic function and unique flavour of the product. In summary, This study offers new insights and data supporting the physiological mechanisms of probiotics and their application in functional fermented foods.