Smart and Functional Probiotic Microorganisms: Emerging Roles in Health-Oriented Fermentation

The incorporation of probiotic microorganisms into fermented foods has long been recognized as a promising strategy to enhance gut health and overall well-being. Conventional probiotics, mainly from the bacterial genera Lactobacillus, Bifidobacterium, Lacticaseibacillus, Levilactobacillus, Lactiplantibacillus and yeast genus Saccharomyces, contribute to gastrointestinal homeostasis, immune modulation, and metabolic balance. Building on these foundations, recent advances in synthetic biology, systems microbiology, and genetic engineering have enabled the development of smart probiotics: engineered or selectively enhanced strains capable of sensing environmental cues and producing targeted bioactive compounds, such as neurotransmitters and anti-inflammatory peptides. These next-generation microorganisms offer precision functionality in food matrices and hold promise for applications in gastrointestinal health, immune support, and gut–brain axis modulation. However, their deployment also raises critical questions regarding biosafety, regulatory approval, and consumer acceptance. This review provides a comprehensive overview of the mechanisms of action, biotechnological strategies, and health-oriented fermentation applications of smart and functional probiotics, emphasizing their role in the future of personalized and evidence-based functional foods.