Bakterienkapsel

Bakterienkapsel refers to the layer that surrounds the cell wall of some bacteria. This layer is typically composed of polysaccharides, though some bacterial capsules are made of polypeptides. The capsule is not essential for bacterial survival but provides significant advantages to the bacterium.

One of the primary functions of the bacterial capsule is to protect the bacterium from phagocytosis by host immune cells, such as macrophages. This protective barrier can prevent the immune system from engulfing and destroying the bacteria, thus aiding in infection establishment and persistence. The capsule can also prevent desiccation, helping bacteria survive in dry environments.

Furthermore, capsules can facilitate bacterial adhesion to surfaces, including host tissues and medical devices like catheters. This adherence is crucial for biofilm formation, which offers further protection and can lead to chronic infections. In some cases, the capsule can act as a virulence factor, contributing directly to the pathogenicity of the microorganism. The composition and structure of bacterial capsules vary widely among different species, leading to diverse functions and implications in microbiology and medicine. Stains like India ink or ruthenium red are often used to visualize capsules in microscopy.