polysaccharideproducing

Polysaccharides are long, often branched polymers composed of monosaccharide units linked by glycosidic bonds. They range from simple linear chains to highly branched networks and can be made from a single monosaccharide type or several. The glycosidic linkage configuration (for example alpha- or beta- glycosidic bonds) and the pattern of branching strongly influence properties such as solubility and digestibility.

Polysaccharides are classified as homopolysaccharides, containing only one type of monosaccharide (e.g., starch and glycogen from glucose; cellulose from glucose beta-1,4), or heteropolysaccharides comprising two or more monosaccharides (e.g., peptidoglycan, agar, and glycosaminoglycans). They can be linear or branched, and their size often reaches millions of monosaccharide units.

Many polysaccharides serve as energy stores, notably starch in plants, and glycogen in animals and fungi. Others provide structural roles, such as cellulose in plant cell walls and chitin in arthropod exoskeletons and fungal cell walls. Bacterial polysaccharides include capsules and extracellular polymers involved in adhesion and biofilm formation. Some heteropolysaccharides function in the extracellular matrix and as mucopolysaccharides in connective tissue.

Polysaccharides are synthesized by glycosyltransferase enzymes that add sugar units from activated donors in the Golgi apparatus or cytosol and are degraded by hydrolytic enzymes and acids. Humans cannot digest most cellulose; dietary polysaccharides contribute to fiber. In industry, polysaccharides such as starch, pectin, agar, alginates, and carrageenan are used as energy sources, thickeners, gelling agents, and stabilizers. The diverse properties of polysaccharides underpin roles in nutrition, microbiology, materials science, and medicine.