Abstract:
The Microbiota-Gut-Brain Axis (MGBA) plays a pivotal role in cognitive function, positioning psychobiotics as a promising strategy for managing neurodegenerative diseases. Lactic acid bacteria (LAB) isolated from traditional fermented foods represent a valuable source of candidate strains, and multi-strain consortia may offer enhanced therapeutic efficacy through synergistic effects. This study evaluated the functional and psychobiotic potential of three Lactic Acid Bacteria (LAB) strains isolated from fermented foods, assessed as monocultures and a multi-strain consortium (MIX). The research encompassed an initial screening of the individual strains and the MIX for mucin adhesion, stability in a static in vitro digestion model, and amino acid profiling. Subsequently, the LAB MIX underwent long-term evaluation in a dynamic gastrointestinal model (SHIME®) inoculated with microbiota from a patient with Alzheimer's disease (AD), during which alterations in gut microbiota composition and the metabolism of selected amino acids and organic acids (SCFA and BCFA) were analyzed.
Results showed that the LAB MIX exhibited high stability under digestive stress and effective mucoadhesive properties. Furthermore, the consortium demonstrated a distinct metabolic signature, driving enhanced functional effects that complemented or exceeded those observed in individual monocultures. In the SHIME® model, the MIX induced significant, site-specific shifts in microbial composition, notably increasing lactobacilli abundance. These taxonomic changes correlated with an enriched metabolic profile, including elevated levels of GABA precursors and amino acids with antioxidant potential, which are critical for MGBA modulation. SCFA and BCFA profiles remained stable, with a slight increase in propionic acid and a decrease in isobutyric acid in the arm supplemented with the MIX. These results identify the LAB consortium as a compelling psychobiotic candidate. Further in vivo and clinical studies are now required to validate its therapeutic potential for MGBA modulation.
