The correct answer is: B) alcohol-acetone
Gram staining includes next steps:
• Fixation- usually by heating or by using methanol
• Primary stain (crystal violet)- it stains all cells blue/purple
• Mordant- added to form a crystal violet iodine
• Decolorization- distinguishes gram-positive from gram-negative cells. Acetone or ethanol are usually used. Acetone/ethanol extracts blue dye from Gram - bacteria (the lipid-rich, thin wall) more than from the, Gram + bacteria (lipid poor, thick walled). The Gram -bacteria appear colorless and Gram + bacteria remain blue.
• Safranin-the red dye stains the decolorized Gram- bacteria.
