Autoinducer-2-associated synergy enhances fermentation, stability, and bioactive metabolite production in probiotic fermented milk.

This study investigates how autoinducer-2-mediated quorum sensing influences fermented milk performance. A high-autoinducer-2 base starter (Lactobacillus delbrueckii subsp. bulgaricus XJ51-2, Streptococcus thermophilus MGC23-8) combined with probiotics (Bifidobacterium animalis subsp. lactis BX246, Lactobacillus kefiranofaciens MGE42-8) formed seven starter variants. The four-strain blend demonstrated the shortest fermentation time (7.1 ± 0.1 h), highest viscosity (2375 mPa·s), earliest gelation (4.4 h), and viability >8.7 log CFU/mL after 21 days at 4 °C. Micro-rheology confirmed accelerated gel network formation. Untargeted metabolomics revealed enrichment of bioactive metabolites including glycerophospholipids, exopolysaccharide precursors, phenyllactate, hydroxycinnamates, organic acids, and short-chain fatty acids. These compounds enhance texture and flavor while offering antimicrobial and potential gut health benefits. Our findings suggest that autoinducer-2-associated interactions improve the technological and functional properties of fermented milk, providing a strategy for designing next-generation probiotic dairy products pending functional validation.