Which chemical is used as a decolorizer in the Gram staining procedure?

In the Gram staining procedure, the decolorizer used is typically alcohol or acetone. This step is crucial because it differentiates between Gram-positive and Gram-negative bacteria based on the structural differences in their cell walls.

During the staining process, initial staining with crystal violet is followed by a mordant, usually iodine, which forms a complex with the crystal violet to enhance its binding to the bacterial cells. When the decolorizer (alcohol or acetone) is applied, it removes the crystal violet from Gram-negative bacteria, which have a thinner peptidoglycan layer surrounded by an outer membrane. A significant feature of Gram-negative bacteria is that they lose the initial crystal violet color during this decolorization step, allowing for the subsequent application of a counterstain (often safranin), which will stain these bacteria red or pink.

In contrast, Gram-positive bacteria, which have a thicker peptidoglycan layer, retain the crystal violet even after the decolorizing step, keeping them purple. This differential staining process is fundamental in microbiology for identifying and classifying bacterial species based on their cell wall composition.

Therefore, alcohol or acetone's role as the decolorizer is critical in achieving a reliable and informative