Question

What result would you expect if you were to perform an endospore stain on an acid-fast bacterium?

Answer 1

In Endospore staining, malachite green in the main stain. It is not taken up by spores easily. Heat treatment is used to force the stain through the tough cell wall of the spores. Once, it is taken up by the spores, it cannot be destained by the destaining solution. Therefore, it will appear green while the rest of the vegetative cells appear pink (Stained by safranin).

Acid fast bacilli have a waxy cell wall made up of mycolic acid. This cell wall is resistant to chemicals and dyes. However, when heat is applied, the dyes can be taken up by the cells. This is how acid-fast bacilli are identified where the carbol fuchsin forces into the cell when heat is applied.

When acid fast bacteria are heated with a solution of malachite green, the dye is able to stain these bacilli. Hence, the entire bacterium will appear as green. Non-acid-fast bacteria appear as pink.