Gram staining solution

Gram staining is a widely used differential staining method in bacteriology. After initial crystal violet staining and iodine solution mordant staining, a water-insoluble crystal violet and iodine complex is formed in the cell wall, which is Gram-positive. The bacterial cell wall is thicker, the peptidoglycan network has many layers and the cross-linking is dense. When ethanol is decolorized, the peptidoglycan dehydration reduces the pore size, so the crystal violet-iodine complex is retained on the cell membrane, which is purple. Gram-negative bacteria have thin cell walls, high lipid content in the outer membrane layer, thin peptidoglycan layer and poor cross-linking. After decolorization, the lipid outer membrane quickly dissolves, the gaps are enlarged, and the crystal violet and iodine complexes dissolve, so ethanol After bleaching, it is re-stained with saffron to turn red.