Probiotic-Derived Extracellular Vesicles as Next-Generation Postbiotics: Biogenesis, Host Interactions, and Translational Challenges

Probiotic-derived extracellular vesicles (PEVs) are membrane-enclosed particles carrying diverse microbial molecules, with potential as next-generation postbiotic platforms. This review compares vesicle biogenesis and composition across Gram-negative bacteria, Gram-positive bacteria, and probiotic yeasts, emphasizing how producer biology shapes characterization and host interactions. Vesicle uptake, functional cargo delivery, and causal attribution are distinguished to assess evidence for intestinal barrier reinforcement, immune modulation, metabolic effects, and gut-organ communication. Available evidence most consistently supports intestinal barrier protection and innate immune modulation, whereas cargo-specific mechanisms and intact-vesicle trafficking to distal organs remain insufficiently resolved. Mechanistic assessment requires complementary evidence concerning vesicle identity, cargo necessity and rescue, receptor involvement, and biodistribution. Key translational priorities include reproducible production, standardized dose reporting, validated potency assays, and safety evaluation. Together, these considerations provide a basis for evaluating the potential of PEVs as defined postbiotic preparations for food and nutrition applications.