The main purpose of capsule stain is to distinguish capsular material from the bacterial cell. A capsule is a gelatinous outer layer secreted by bacterial cell and that surrounds and adheres to the cell wall. Most capsules are composed of polysaccharides, but some are composed of polypeptides.
Also question is, what is the color of the capsule in the capsule stain?
The background will be dark (color of india ink). The bacterial cells will be stained purple (bacterial cells takes crystal violet-basic dyes as they are negatively charged). The capsule (if present) will appear clear against the dark background (capsule does not take any stain).
What kind of stain is the capsule stain?
The capsule stain employs an acidic stain and a basic stain to detect capsule production. Capsules are formed by organisms such as Klebsiella pneumoniae . Most capsules are composed of polysaccharides, but some are composed of polypeptides.
Why do they call a capsular stain a negative stain?
A basic stain stains the bacteria (the stain is a positively charged molecule that attaches to cells which are negatively charged or to negatively charged molecules in cells.) A negative stain does not stain cells (why its called a negative stain), it stains the background around the cells.