Question

Why is a capsule advantageous to a bacterium?
(a) It provides means of locomotion
(b) It allows bacteria to “hide” from host’s immune system
(c) It allows the bacterium to attach to surface
(d) It protects the bacterium from desiccation

Answer 1

The capsule is considered a virulence factor since it improves bacteria's ability to cause disease. It protects macrophages from engulfing the bacterial cell. They also exclude bacterial viruses and most toxic materials such as detergents which are hydrophobic.

Complete step by step answer:
A durable and dense mucilage covering is the capsule. It gives bacteria protection against the immune system of the host. As it increases the capacity of bacteria to cause disease ( e.g. prevents phagocytosis), the capsule is called a virulence factor. The capsule is a protective coating made up of basic sugar (polysaccharides) polymers and amino acids of the bacterial cell. This protects a bacterial cell from white blood cell absorption and destruction (phagocytosis) and allows it to hide from the host immune system.
So, the correct answer is, ‘(b) It allows bacteria to “hide” from the host's immune system’.

Additional information:
In several bacteria, the bacterial capsule is a large structure. It is a layer of polysaccharide that lies outside the envelope of the cell and is thus considered part of a bacterial cell's outer envelope. It is a well-organized layer, not easily washed off, and maybe the source of different diseases.
Some microbial cells are stationary but most of them have a way of moving around and the process is called locomotion. Flagella are involved in the bacterial locomotion process. They propel the cell either backward or forward. With a kind of movement called gliding, bacteria without flagella may also move around.

Note: The capsule is a membrane that lies beyond the bacterial cell wall. The bacterial capsule usually consists of a layer of polysaccharide that lies outside the envelope of the cell. Capsules are present in gram-positive and gram-negative bacteria. For phagocytosis to occur a capsule-specific antibody may be necessary.