What is the Difference Between Capsule and Glycocalyx?

The difference between a capsule and a glycocalyx lies in their structure, composition, and function. Both are extracellular materials secreted by bacterial cells, but they serve different purposes and have distinct properties:

Capsule:

• An organized, well-defined, and condensed extracellular layer tightly bound to the cell envelope of bacteria.
• Composed of polysaccharides.
• Provides protection against phagocytosis and helps bacteria adhere to surfaces.
• Capsules are firmly attached to the cell wall and are difficult to wash off.
• The presence of a capsule is a virulence factor of bacteria.

Glycocalyx:

• An additional layer composed of polysaccharides and/or polypeptides outside the cell wall.
• Protects bacteria from external conditions and helps in adhering to surfaces.
• Glycocalyx can exist in two forms: capsule and slime layer.
• The slime layer is an unorganized, loosely associated extracellular layer that surrounds the bacterial cells.
• Composed of exopolysaccharides, glycoproteins, and glycolipids.

In summary, the capsule is a highly organized, tightly bound, and well-defined extracellular layer that is firmly attached to the bacterial cell wall, providing protection and adhesion properties. On the other hand, the glycocalyx is an additional layer outside the cell wall that can exist in two forms (capsule and slime layer) and is composed of different materials, providing protection and adherence to surfaces.

Comparative Table: Capsule vs Glycocalyx

Here is a table comparing the differences between a capsule and a glycocalyx:

In summary, the capsule is an organized, well-defined layer tightly attached to the bacterial cell wall, while the glycocalyx is an additional layer composed of polysaccharides and/or polypeptides outside the cell wall. The capsule is difficult to wash off and serves as a virulence factor, while the glycocalyx aids bacteria in avoiding phagocytosis and forming biofilms.