Question Detail

MIC 121 MCB 102 BACTERIA Objective Question

Question

During the Gram staining technique, which chemical acts as a counterstain, giving Gram-negative bacteria their characteristic pink or red color?
Options
A Crystal violet
B Iodine
C Alcohol
D Safranin
Correct Answer
Correct Answer

Option D is the correct answer.

Detailed Explanation

The Gram staining technique involves several steps: staining with crystal violet (purple dye), adding iodine (mordant), rinsing with alcohol (decolorizer), and then re-staining with a pink dye called safranin. Safranin is the counterstain that colors the decolorized Gram-negative cells pink/red.

Hint

This dye is applied after the decolorization step.

Question Info