Question

Pick up incorrect statement about bacterial capsule
A) capsular material is antigenic in nature.
B) it protects bacteria by inhibiting phagocytosis
C) it cannot be stained by gram’s stains
D) it is acid fast in nature

Answer 1

The bacterial capsule is a large structure of many bacteria. It is a polysaccharide layer that lies outside the cell envelope, and is thus deemed part of the outer envelope of a bacterial cell

Complete answer:
The acid fast stain is a differential stain used to identify acid fast organisms such as members of genus mycobacterium. They are characterised by wax like nearly impermeable cell walls, they contain mycolic acid and large amounts of fatty acids, waxes and complex lipids.

The acid fastness character is present in the cell wall of the bacteria belonging to acid fast bacterial groups eg. Mycobacterium which causes tuberculosis and leprosy. The mycobacterium (tb causing): cell wall is made up of mycolic acid (fatty acid). It is selectively permeable. Structure is like unit membrane instead of cholesterol.

The bacterial capsules performs the following functions
-Prevention of desiccation
-Protection from phagocytosis
-Protection from toxic chemical and drugs
-Protection of virus
-Bacterial capsules are non-ionic, so neither acidic nor basic stains will adhere to their surfaces.

The incorrect statement from above is option (D) i.e. it is acid fast in nature.

Note: The glycocalyx, also known as the pericellular matrix, is a glycoprotein and glycolipid covering that surrounds the cell membranes of some bacteria, epithelia, and other cells. Glycocalyx is made of mucilage sheath. It may occur in the form of loose sheath called slime layer or thick or tough called capsule. So this is what we call a bacterial capsule.