Microbial exopolysaccharides as postbiotics: Structure, function, and translational potential

The approach of leveraging microbial benefits has been redefined, especially in enhancing human health, with a shift from probiotics to postbiotics. Postbiotic compounds have gained significant interest, with microbial exopolysaccharides standing out due to their complex structures, diverse functions, and ability to provide benefits without requiring live microbial cells. High-molecular-weight polysaccharides, known as exopolysaccharides, are produced and secreted by a wide range of microorganisms, particularly lactic acid bacteria and bifidobacteria. Their roles reach beyond providing structural support; they also influence biofilm formation, modulate the host's immune response, exhibit antioxidant activity, and contribute to antimicrobial defense. This review offers a comprehensive examination of the microbial origins, classification, biosynthetic pathways, and physical and chemical properties of exopolysaccharides. It emphasizes recent advances in extraction, purification, and structural analysis methods, including both traditional and modern techniques. The functional properties of exopolysaccharides, such as immunomodulatory, antioxidant, anti-inflammatory, and antitumor effects, are explored in detail along with their underlying mechanisms. The review highlights applications of exopolysaccharides in food technology, pharmaceuticals, and biomedical engineering, demonstrating their versatility as postbiotic biomolecules. Although exopolysaccharides show promising bioactivities, challenges remain in scaling up production and achieving standardization due to strain-specific variability, low yields, and regulatory hurdles. While most existing studies rely on conventional biochemical and structural analyses, the emerging multi-omics, bioinformatics, and AI-driven approaches are discussed to provide predictive and mechanistic insights into EPS structure, function relationships. Exopolysaccharides represent a rapidly evolving area in postbiotic research, underscoring the need for translational research, clinical validation, and industry-driven development to unlock their full potential as next-generation functional polymers.