The stain used to stain endospores in gram-positive bacteria is Malachite green.
Here's why:
1. Malachite green is a green-colored dye that is commonly used in endospore staining procedures to highlight the presence of endospores in bacterial cells.
2. In the endospore staining technique, malachite green is applied to the heat-fixed bacterial smear and then heat is used to facilitate the penetration of the dye into the endospores.
3. After staining with malachite green, the sample is washed with water to remove excess dye, and then counterstained with safranin to visualize the vegetative cells.
4. The endospores, which are resistant structures formed by some bacteria as a means of survival in harsh conditions, retain the malachite green stain even after the washing steps, appearing as green structures under the microscope, while the vegetative cells take up the safranin counterstain and appear pink or red.
Therefore, in the context of staining endospores in gram-positive bacteria, Malachite green is the stain of choice.
