Capsular and Extracellular Polysaccharides

In addition to the cell wall and a possible capsule as primary and secondary protective layers, respectively, some fungal cells have developed mechanisms for the production of extracellular polysaccharides (EPS) similarly to the capsule, the EPS forms a complex matrix used as a protective barrier when the cells are subjected to specific environmental or stressful constraints (such as salt or pH stress). But, contrary to the 

Division Species Polysaccharide Sugar monomers References 

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Each polysaccharide structure is synthesized by a distinct set of enzymes, and the biosyntheses of the individual structures will not be discussed here. The biosynthetic gene clusters for many different capsular and extracellular polysaccharides are known, and many of the enzymes involved have been characterized. For a general review of the genetics and biochemistry of CPS production, the reader is referred to a review by Roberts [321]. There are also many excellent reviews discussing capsule formation in individual bacteria, including H. influenzae [322], S. Aureus [323], E. coli [312], and pathogenic streptococci [324,325]. 

Capsular and extracellular polysaccharides are involved in several aspects of cellular behavior that are tied to bacterial survival and virulence [321]. The capsule layer provides a physical barrier that prevents the bacteria from drying out, aiding in survival outside a host. CPS are also involved in colonization and biofilm formation. In some bacteria CPS promote adherence to surfaces, aiding colonization and biofilm formation, while CPS in other bacteria inhibit adhesion and biofilm formation [344]. 

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