Weissella: From Beneficial Probiotics to Opportunistic Pathogens—A Review

Weissella, a genus of Gram-positive, facultatively anaerobic lactic acid bacteria, has emerged as a significant component of human microbiota with diverse biotechnological and therapeutic applications. This narrative review examines the current state of knowledge regarding Weissella taxonomy, physiological characteristics, and functional properties based on research spanning from 1993 to present. Weissella species demonstrate remarkable versatility, producing bioactive metabolites including exopolysaccharides (EPS), bacteriocins, and organic acids that confer antimicrobial, antioxidant, and anti-inflammatory properties. These bacteria show significant potential in food fermentation, probiotic applications, and therapeutic interventions for gut health, obesity, and inflammatory conditions. However, challenges persist regarding strain-specific pathogenicity, particularly with W. confusa as an opportunistic pathogen, and the need for comprehensive safety evaluations. Current limitations include variability in probiotic efficacy, incomplete understanding of host-microbe interactions, and gaps in metabolic pathway characterization. This review provides a foundation for advancing Weissella research and applications while highlighting critical areas requiring further investigation to fully harness their biotechnological and therapeutic potential.