Question

Which step in the Gram stain is the critical step in differentiating Gram negative cells from Gram positive cells?

Answer 1

Answer:

The rapid decolorization with ethanol or acetone

and counterstaining with safranin

When a decolorizer such as alcohol or acetone is added, it interacts with the lipids of the cell membrane. A gram-negative cell loses its outer lipopolysaccharide membrane, and the inner peptidoglycan layer is left exposed: when safranin is added they will turn red. Conversely, gram-positives retain the Cristal violet and will color in purple