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Algae possess carbohydrates-rich cell walls which composed highly coordinated network of different polysaccharides, water and metals. All polysaccharides that present in algae, either they will be in the form of reserve food or structural component of their cell wall. Polysaccharides that present in algae, act as main representative of their corresponding taxa, and it could be speculated that algal cell wall polysaccharides also act as taxonomical and structural marker. Structurally, the algal cell wall has crystalline and fibrous polysaccharides like, cellulose, hemicellulose and xylans which have embedded in to jelly matrix of carboxylic and sulfated polysaccharides. Alongside the proteins, proteoglycan and phenolic also help in cell wall formation. Similar, different algae produce different polysaccharides such as, the cell wall of green algae have structurally different sulfated or carboxylic polysaccharides. The cell wall of red algae has composite structures of different sugars such as, xylans fibrils, mannan, cellulose, carrageenan and ager. The cell wall of brown algae is made up of cellulosic fibrils, alginates and fucoidans as matrix polysaccharides [32, 33].

Algal cell wall polysaccharides have significant diversity in structure, molecular mass, composition, glycosidic linkages, the arrangement of the sugar residues and the existence or configuration of the functional moieties such as, sulfate semi-esters, methyl-ether, carboxylates, acetyl-ester, etc. Also, the cell wall polysaccharides have linear or branched structure and it may be varied due to the size of side chains or the numbers of branching to internal or peripheral side [33, 34].