The cell wall is the part of the bacterial cell is most involved in gram staining. This is because the two types of gram bacteria which are known as the gram positive and gram negative bacteria have different and unique cell wall constituents.
The gram positive bacteria have a cell wall composed of peptidoglycan while the gram negative bacteria have cell wall composed of a thin layer of peptidoglycan and an outer layer of lipopolysaccharide. They give different results when stained ; gram positive bacteria retains the crystal violet color of the reagent used while the gram negative bacteria gives a pale reddish color.
