What is the main function of a bacterial capsule?

The main function of a bacterial capsule is to provide protection from phagocytosis. This gelatinous layer surrounds the cell wall of some bacteria, making it more difficult for immune cells, such as macrophages and neutrophils, to engulf and destroy the bacteria. By evading phagocytosis, bacteria with a capsule can enhance their survival in the host environment, contributing to their virulence and ability to cause infections.

The capsule also plays additional roles such as helping with adherence to surfaces and forming biofilms, but its primary protective function against the host's immune response is crucial for the pathogenicity of encapsulated bacteria. This characteristic is particularly important in the context of infectious diseases, where the ability to resist being engulfed by immune cells can determine the outcome of an infection.