Question

In the Gram staining procedure, all the bacterial cells get stained with

• A. Mercuric chloride
• B. Crystal violet
• C. Malachite green
• D. Saffranin

Answer 1

The correct option is B Crystal violet

Gram staining procedure is based on the principle of the ability of microorganisms to retain color of the stains used during the gram staining process. Gram-positive bacteria retain purple color after staining with crystal violet stain. They are not decolorized by treatment with alcohol. Gram-negative bacteria also get stained with crystal violet stain. However, they are decolorized by the alcohol and lose purple color. When again stained with the second stain safranin, they retain pink color. This major difference is due to the difference in the cell wall component of both the bacteria.

Thus, the correct answer is 'Crystal violet.'