The bacterial capsule is a large structure common to many bacteria. It is a polysaccharide layer that lies outside the cell envelope, and is … 展开

Most bacterial capsules are composed of polysaccharide, but some species use other materials, such as poly-D-glutamic acid in Bacillus anthracis. … 展开

The bacterial capsule serves as a shield, giving protection from toxins, and from drying out. Capsules allow adhesion to surfaces and help enable the bacteria to evade the host immune system. The water content in the capsule gives the protection against drying out. The … 展开

The capsule is found most commonly among gram-negative bacteria:
• Escherichia coli (in some strains)
• Neisseria meningitidis
• Klebsiella pneumoniae 展开

1. India ink staining: the capsule appears as a clear halo around the bacterium as the ink can't penetrate the capsule.
2. Maneval's capsule stain: the capsule appears as a clear halo between the pink-stained bacterium and the bluish-grey stained background. The … 展开

Vaccination using capsular material is effective against some organisms (e.g., H. influenzae type b, S. pneumoniae, and N. meningitidis ). However, polysaccharides are not highly antigenic, especially in children, so many capsular vaccines contain polysaccharides 展开

• Bacterial cell structure
• Quellung reaction, a method to visualize capsule under a microscope 展开