Functional and Psychobiotic Potential of a Food-Derived Multi-Strain Lactic Acid Bacteria Consortium: An In Vitro Evaluation Using Static Digestion and SHIME® Models

Background/Objectives: The microbiota–gut–brain axis (MGBA) plays a pivotal role in cognitive function, making psychobiotics a promising strategy for managing neurodegenerative diseases. Lactic acid bacteria (LAB) 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). Methods: The research encompassed an initial screening of the individual strains and the MIX, assessing their adhesion to mucin, 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, during which alterations in gut microbiota composition and amino acid metabolism were analyzed. Results: The LAB MIX demonstrated 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 crucial for MGBA modulation. Conclusions: These results identify the LAB consortium as a compelling psychobiotic candidate. Further in-depth in vivo and clinical studies are required to validate its therapeutic potential for MGBA modulation.