Why are older cultures typically used for endospore staining

Why are older cultures typically used for endospore staining.

Solution

The spore stain is used to identify the spores of resistant microorganisms among other vegetative cells. In Schaeffer-Fulton methodology, bacterial smears are heat fixed by using a steam bath and stained with Malachite Green. This can soften the outer coverings of the spore and therefore the primary stain gets stick with the structure. The structure again becomes hard upon cooling; both the spore and vegetative cells appear green in color. When we wash these cells with water, the spores do not lose the stain, but the stain of vegetative cells can be easily washed away.

Older cultures likely to more endospores because the spore formation occurs during the stressful conditions like the depletion of nutrients. Thus, the older stains are preferred for endospore staining.