What color do gram-positive bacteria stain?

What color do gram-positive bacteria stain?

• A. Pink
• B. Purple
• C. Clear
• D. Green

Answer: (B)

Gram-positive bacteria stain purple due to the presence of a thick peptidoglycan layer in their cell wall. The Gram staining procedure involves applying a crystal violet dye to the bacterial sample, which binds to the peptidoglycan. After applying iodine, which acts as a mordant, the bacteria are washed with alcohol or acetone. The thick peptidoglycan layer in gram-positive bacteria retains the crystal violet stain even after the decolorization step, resulting in the purple color. This characteristic is essential for identifying gram-positive organisms in various clinical and laboratory settings, as it provides information on the structure of the bacterial cell wall and can guide treatment options.

Gram-positive bacteria stain purple due to the presence of a thick peptidoglycan layer in their cell wall. The Gram staining procedure involves applying a crystal violet dye to the bacterial sample, which binds to the peptidoglycan. After applying iodine, which acts as a mordant, the bacteria are washed with alcohol or acetone. The thick peptidoglycan layer in gram-positive bacteria retains the crystal violet stain even after the decolorization step, resulting in the purple color. This characteristic is essential for identifying gram-positive organisms in various clinical and laboratory settings, as it provides information on the structure of the bacterial cell wall and can guide treatment options.