Bacterial capsule (may be missing)
It is a viscous outer layer with a thickness ranging between 100 and 400 Å. It is very common in pathogenic bacteria because it facilitates adherence to the host's tissues. It is not present in all prokaryotes.
This capsule is rich in polysaccharides and protein molecules.
The bacterial capsule is attributed the following functions:
- Attach the pathogenic bacteria to its host.
- It protects the bacteria from the drying medium.
- It regulates the processes of exchange of water and nutrients, in addition to serving as a storehouse of nutrients.
- Defense against antibodies, bacteriophages and phagocytic cells.
- It allows the formation of colonies of bacteria.