Metabolic interactions of Limosilactobacillus reuteri ZJ625 and Ligilactobacillus salivarius ZJ614 in co-culture: implications for multi-strain probiotics

Abstract Aims Limosilactobacillus reuteri ZJ625 and Ligilactobacillus salivarius ZJ614 are potential probiotic bacteria. The mechanisms of enhanced benefits by muti-strain probiotics are yet fully understood. We elucidated the influence of co-culturing on the metabolite profiles of Limosilactobacillus reuteri ZJ625 and Ligilactobacillus salivarius ZJ614 to decipher the impacts of co-culturing on metabolic interactions between the strains. Methods and results Limosilactobacillus reuteri ZJ625 and Ligilactobacillus salivarius ZJ614 were grown in single and co-cultures in defined media. Bacterial cell metabolites were extracted at the mid-stationary growth phase and analysed using two-dimensional gas chromatography–time-of-flight mass spectrometry (GC × GC–TOFMS). Mass-spectral data were preprocessed and analysed using unsupervised and supervised methods based on the group allocations. A total of 1387 metabolites were identified, with 18.31% significant metabolites (P < 0.05) and 10.17% differential metabolites (P < 0.05, variable importance on projection > 1). The differential metabolites identified include arabinofuranose, methyl-galactoside, N-acetylglutamic acid, phosphoric acid, and decanoic acid. The metabolites impacted carbohydrate and amino-sugar metabolism. Conclusion Co-culturing of Limosilactobacillus reuteri ZJ625 and Ligilactobacillus salivarius ZJ614 influenced the metabolite profiles of the strains and impacted metabolic/biosynthetic pathways, indicating cell-to-cell interactions between the strains.