What is the result of under-decolorization during the Gram staining process?

During the Gram staining process, under-decolorization typically leads to Gram-negative bacteria retaining the crystal violet stain, causing them to appear purple instead of pink. Gram-negative bacteria normally lose the crystal violet color during the decolorization step because they have a thinner peptidoglycan layer and an outer membrane that does not retain the stain in the presence of alcohol or acetone used in that step.

In the case of under-decolorization, the decolorizing agent does not adequately penetrate the cell wall of the Gram-negative bacteria, which leads to the incorrect retention of the purple crystal violet stain. As a result, what should appear pink (indicating a Gram-negative result) instead shows a purple coloration, misidentifying the Gram-negative bacteria as Gram-positive. This can lead to confusion in identifying the type of bacteria based on Gram staining results.