Answer and explanation
All color is lost after washing gram-negative bacteria with alcohol. Gram-negative bacteria do not keep the color when washed with alcohol due to the fact that the outer face of the exterior membrane of Gram-negative bacteria consists of lipopolysaccharides, a part of which is integrated into the membrane lipids.
So what happens is that the outer membrane of Gram negative bacteria is degraded and the thinner peptidoglycan layer of Gram negative cells is unable to retain the crystal violet-iodine complex and the color is lost.
