From bacterial to microbiome-derived vesicles: genome-informed identity, source qualification, and translational quality for skin-directed cosmetics.

Bacterial extracellular vesicles (BEVs) are increasingly proposed as materials for skin-directed cosmetics, yet rapid adoption of "exosome" terminology has outpaced clarity on their origin, composition, and manufacturing quality. This review argues that the value of BEVs depends on scientific discipline rather than marketing appeal, and that they are promising because they are biologically potent, not because they are intrinsically benign. We retain BEVs as the scientific umbrella term for vesicles released by bacteria and we propose the term microbiome-derived vesicles (MDVs) as the consumer-facing designation for qualified commensal BEVs - a surface term that avoids the difficulty of "bacterial" while its definition preserves bacterial provenance. We develop a three-axis framework for BEV identity that integrates compositional analysis, producer-strain genomics, and functional or safety profiling, and we position whole-genome sequencing (WGS) as decisive for source qualification and mechanistic interpretation but insufficient to prove the efficacy of a purified preparation. Building on this framework, we summarize isolation, purification, and analytical characterization requirements; interpret current skin-efficacy evidence in light of its methodological limits; and discuss formulation, cosmetic application, regulatory positioning, and manufacturable quality. We conclude that transparent bacterial provenance, reproducible preparation, and evidence proportionate to the claims made are prerequisites for evaluating commensal BEVs, described for skin applications as MDVs, as a scientifically defined cosmetic platform.