What color do Gram-Positive bacteria stain?

Gram-positive bacteria stain blue or purple due to the thicker peptidoglycan layer in their cell walls. During the Gram staining procedure, a crystal violet dye is applied first, which penetrates the thick peptidoglycan layer and binds effectively. When iodine is added, it forms a complex with the crystal violet, further trapping it within the cell wall. During the decolorization step, gram-positive bacteria retain the crystal violet dye, resulting in a blue or purple appearance under a microscope, while gram-negative bacteria lose the crystal violet and take up the counterstain, which is typically safranin, leading them to appear red or pink. The unique structural components of gram-positive bacteria, particularly their robust cell wall, play a crucial role in this staining process and are a key factor in differentiating between these two groups of bacteria.