Читать книгу Polysaccharides - Группа авторов - Страница 49

Bacterial cell wall have a mesh-like complex structure that is essential for the maintenance of structural integrity and shape of most of the bacteria. It is also responsible to provide shape, protection to the bacterial cell and medium of interaction with bacterial environment. The cell wall of Gram-positive bacteria is exclusively composed of polysaccharides that are merged in peptidoglycan that surround the plasma membrane of the cell. Further, the bacterial polysaccharides have been distributed into the extracellular and intracellular saccharides on the basis of their morphology. The intracellular polysaccharides placed inside the bacterial cell, the part of the plasma membrane, are part of the peptidoglycan, lipopolysaccharides, periplasmic glucans and capsular polysaccharides that are present in the structural part of the bacterial cell wall (Figure 2.4) [48, 49].

Extracellular polysaccharides have a branched structure which is made of sugars and their derivatives in repeated sequence and are known as exopolysaccharides. On the basis of sugar units or their derivatives, the exopolysaccharides have further two types like, homopolysaccharides that include pullulan curdlan, cellulose, etc and heteropolysaccharides such as xanthan and gellan. The bacterial polysaccharides provide evolutionary adaptation to the cell through helping in cellular attachment, prevent from desiccation and act as virulence factor. Bacterial exopolysaccharides have been exceedingly used in food, textile, papers and pharmaceutical industry such as in cosmetics, wound dressing and medicines [50–54].