The capsule in bacteria serves which function?
Bacterial capsules are compact, highly hydrated layers of acidic polysaccharide or occasionally polypeptide that tightly surround the cell external to the wall, distinct from loosely associated slime that washes away easily. Capsular chemistry is diverse, ranging from K-antigens composed of repeating sugar units to hyaluronic acid that mimics host connective tissue, conferring molecular mimicry and serotype specificity. Functionally, capsules act as major virulence factors by shielding pathogen-associated molecular patterns such as peptidoglycan and outer membrane proteins from innate immune s
Ref: Prescott's Microbiology, 11th ed., Chapter 3: Capsules and Glycocalyx; Whitfield, Ann Rev Biochem 2006, Capsular Polysaccharides.
