Question

Sequence of steps in gram’s staining technique in the identification of bacteria are:

• A. Crystal violet - ethanol - Grams Iodine - Safranin
• B. Crystal violet - Safranin - Grams Iodine - ethanol
• C. Crystal violet - ethanol - Safranin - Grams Iodine
• D. Crystal violet - Grams Iodine - ethanol - Safranin

Hint:

Gram's staining technique is widely used in microbiology to distinguish between Gram-positive and Gram-negative bacteria.

Answer 1

The Correct Option is D

Gram's staining technique involves the following sequence:
1. Crystal violet is the primary stain applied to the bacterial sample.
2. Grams iodine is used as a mordant to fix the crystal violet stain within the bacterial cells.
3. Ethanol or acetone is applied to decolorize the cells. This step removes the stain from Gram-negative bacteria, leaving Gram-positive bacteria colored.
4. Safranin is the counterstain, which stains the decolorized Gram-negative bacteria red or pink.
- Option (1) is incorrect because the correct sequence is Crystal violet, Iodine, ethanol, and then Safranin.
- Option (2) is incorrect because Safranin should be the last step.
- Option (3) is incorrect because the iodine step should come before the decolorization (ethanol) step.
- Option (4) is the correct answer, which follows the correct order: Crystal violet, Grams Iodine, ethanol, and Safranin.
Thus, the correct answer is option (4): Crystal violet - Grams Iodine - ethanol - Safranin.