What is the best explanation for a Gram-positive bacterium appearing pink after performing a Gram stain?
A) The crystal violet was left on for too long.
B) The iodine was left on for too long.
C) The decolorizer was left on for too long.
D) The safranin was left on for too long.
E) The stain was properly performed.

Question

Quizplus · Accepted Answer

The decolorizer is the critical step in a Gram stain that differentiates between Gram-positive and Gram-negative bacteria. Gram-positive bacteria have a thick peptidoglycan layer in their cell walls, which helps retain the crystal violet-iodine complex. When the decolorizer is applied, it removes the crystal violet-iodine complex from Gram-negative bacteria but not from Gram-positive bacteria. If the decolorizer is left on for too long or is too strong, it can remove the crystal violet-iodine complex from Gram-positive bacteria as well, causing them to appear pink after the application of the counterstain, safranin.

What Is the Best Explanation for a Gram-Positive Bacterium Appearing