Non-Conventional Yeasts with Probiotic Potential: Diversity, Functional Role, Sustainable Bioprocessing and Local Relevance.

Saccharomyces boulardii is the most clinically established probiotic yeast, but non-Saccharomyces strains also exhibit probiotic potential. These non-conventional yeasts can survive gastrointestinal conditions, adhere to intestinal mucosa, and modulate host physiology in human and veterinary contexts. This review examines their diversity, probiotic traits, safety requirements, and applications, emphasizing strain recovery from fermented foods, environmental niches, and local biotopes. Kluyveromyces marxianus, Debaryomyces hansenii, and Pichia kudriavzevii illustrate this potential, showing promising in vitro and animal evidence, technological versatility, and strain-level safety constraints. Finally, we discuss the path to application and commercialization, including sustainable biomass production, encapsulation, and incorporation into food matrices. The transition from promising isolates to commercial products will require standardized strain-level assessments and clinical studies.