Crystal Violet Solution

Crystal violet, also known as gentian violet or methyl violet, is the N-hexamethylated derivative of pararosaniline. It is a basic, cationic, acidotropic protein dye used in histological and bacteriological staining. It is well-known for its antibacterial and antifungal properties.

It stains the fatty portions of sebaceous sweat a deep purple color. Crystal violet can also be used to enhance bloody fingerprints. This dye is harmful if inhaled, swallowed or absorbed through skin, contact may cause cancer, severe eye irritation in human beings.

Crystal violet solution for use in Brown-Hopps method for Gram-positive and Gram-negative bacterial staining.

Crystal violet is the primary stain in Gram staining. It infiltrates the peptidoglycan-rich cell wall of Gram-positive bacteria, and forms entrapped complexes with Gram′s iodine that retain the purple color post-decolorization. Thus, Gram-positive bacteria can be differentiated from Gram-negative bacteria whose peptidoglycan layer is considerably thinner.

The antimicrobial effects of crystal violet can be attributed to free radical generation and formation of unionized bacterial complexes with the dye. It has also been reported to inhibit protein synthesis and bacterial cell wall formation. It is especially effective against Gram-positive bacteria.