Diatom-Derived Biochemicals: An In-Depth Analysis of Polysaccharides, Extraction Methodologies, and Diverse...

Diatoms are unicellular eukaryotic algae, renowned for their intricately patterned silica cell walls, which exhibit remarkable morphological precision and nanostructural complexity. They possess a unique and rich biochemical profile and are prolific producers of biologically active polysaccharides, broadly categorized as intracellular, extracellular (primarily sulfated), and cell wall-associated types. These polysaccharides play vital roles in biofilm formation, carbon cycling, nutrient storage, and ecosystem dynamics, while also holding substantial promises in commercial and biotechnological fields. This review provides an integrated overview of diatom polysaccharide chemotypes-storage β-glucans, cell-wall uronic- and sulfate-rich scaffolds, and extracellular exopolymers-and evaluates the conventional versus emerging extraction and purification techniques, discussing trade-offs in yield, selectivity, and polymer integrity. The diverse structural characterization methods for elucidating monosaccharide linkages and functional modifications have been reviewed. The genomic and metabolic insights into polysaccharide biosynthesis have been elaborated along with elucidation of the relationship between extracellular polymeric substances and bacterial community assembly. The multifaceted applications of diatom-derived polysaccharides in carbon sequestration, biomedicine (e.g., anticoagulant, antioxidant, antiviral, anticancer, immunomodulatory agents), materials science, and environmental remediation has been discussed along with the current challenges-species variability, efficient frustule disruption, and scalable processing. The-genomics-guided strain optimization and sustainable bioprocess design holds immense future potential for diatom derive polysaccharides.