ABSTRACT
I. Introduction..................................................................................................479 II. Industrial Applications of Microbial Polysaccharides ................................480 III. Biomedical Applications of Microbial Polysaccharides ............................481 IV. E. coli Capsules ..........................................................................................482 V. Genetic Organization and Regulation of E. coli Group 2
Capsule Gene Clusters ................................................................................482 VI. E. coli Capsules and Glycosaminoglycans..................................................487 VII. Chondroitin Synthases ................................................................................487 VIII. Heparosan Synthases ..................................................................................488 IX. Approaches to Synthesis of Biotechnological Heparin ..............................489 References ..............................................................................................................490
A number of bacteria produce an extracellular polysaccharide (EPS) that is linked to the cell surface.1 Such polysaccharides may be in the form of a discrete structure termed a capsule or they may be in the form of an amorphous layer termed slime, which is loosely associated and easily sloughed off from the cell surface. Bacterial capsules have long been recognized as important virulence determinants in isolates capable of causing infection in humans and animals2 and it is the physicochemical properties of capsules that confer advantageous properties on the bacteria that possess them (Table 16.1). EPS are highly hydrated and constitute more than 95% water.3 This property is thought to aid transmission of encapsulated bacteria from host to host by providing resistance against desiccation.4,5 As the polysaccharide capsule represents the outermost layer of the cell, it is not surprising that the capsule mediates interactions between the bacterium and its immediate environment. Adhesion to abiotic surfaces may result in the establishment of biofilms and EPSmediated interspecies coaggregation within biofilms enhances the colonization of
