Violacein: A Promising Bacterial Secondary Metabolite

Abstract

Pigment is a secondary metabolite produced by microorganisms. As a natural product, bacterial pigments are being studied for their applications in pharmaceutical, food and cosmetic industry. Purple and blue bacterial pigments are less common. Violacein, a purple pigment is an indole derivative with molecular mass of 343.3. Some bacteria like Pseudoalteromonas sp. 520P1, Chromobacterium violaceum, Janthinobacterium lividum, Duganella violaceinigra, Collimonas and Iodobacter species are reported for violacein production. It is produced by vio operon comprising of vioABCDE genes. Violacein production is beneficial to the bacterial cell as it acts as a respiratory pigment involved in the regulation of tryptophan production, active in defensive mechanism and helps cell survival in stressed conditions. Carbon source, pH, temperature, incubation period and agitation rate are factors affecting violacein production. Violacein has shown antibacterial, antifungal, antiviral, anticancer and antiparasitic activity. It also displayed immunostimulatory, gastroprotective and antioxidant properties. Violacein gained industrial importance as a coloring agent in cosmetic, food and textile industries. This review intended to describe the violacein production by bacteria, its advantages to bacteria producing it, factors affecting its production and its applications.