Violacein is a naturally-occurring bis-

indole Indole is an aromatic heterocyclic organic compound with the formula C8 H7 N. It has a bicyclic structure, consisting of a six-membered benzene ring fused to a five-membered pyrrole ring. Indole is widely distributed in the natural environmen ...

pigment A pigment is a colored material that is completely or nearly insoluble in water. In contrast, dyes are typically soluble, at least at some stage in their use. Generally dyes are often organic compounds whereas pigments are often inorganic compo ...

with

antibiotic An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting bacterial infections, and antibiotic medications are widely used in the treatment and prevention of ...

(anti-bacterial, anti-viral, anti-fungal and anti-tumor) properties. Violacein is produced by several species of

bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among ...

, including ''

Chromobacterium violaceum ''Chromobacterium violaceum'' is a Gram-negative, facultative anaerobic, non-sporing coccobacillus. It is motile with the help of a single flagellum which is located at the pole of the coccobacillus. Usually, there are one or two more lateral f ...

'', and gives these organisms their striking purple hues. Violacein shows increasing commercially interesting uses, especially for industrial applications in cosmetics, medicines and fabrics.

Biosynthesis

Violacein is formed by

enzymatic Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products. ...

condensation of two

tryptophan Tryptophan (symbol Trp or W) is an α-amino acid that is used in the biosynthesis of proteins. Tryptophan contains an α-amino group, an α- carboxylic acid group, and a side chain indole, making it a polar molecule with a non-polar aromatic ...

molecules, requiring the action of five proteins. The genes required for its production, ''vioABCDE'', and the regulatory mechanisms employed have been studied within a small number of violacein-producing strains. Production of violacein is controlled by

quorum sensing In biology, quorum sensing or quorum signalling (QS) is the ability to detect and respond to cell population density by gene regulation. As one example, QS enables bacteria to restrict the expression of specific genes to the high cell densities at ...

using acyl-homoserine lactones (AHLs). Only a few genera of bacteria have been reported to produce violacein. These include ''Chromobacterium'', '' Duganella'', ''

Pseudoalteromonas ''Pseudoalteromonas'' is a genus of marine bacteria. In 1995, Gauthier ''et al'' proposed ''Pseudoalteromonas'' as a new genus to be split from ''Alteromonas''. The ''Pseudoalteromonas'' species that were described before 1995 were originally pa ...

'', '' Janthinobacterium'', ''Iodobacter'', '' Rugamonas'', and ''Massilia''''''.

Antibiotic activity

Violacein is known to have diverse biological activities, including as a

cytotoxic Cytotoxicity is the quality of being toxic to cells. Examples of toxic agents are an immune cell or some types of venom, e.g. from the puff adder (''Bitis arietans'') or brown recluse spider (''Loxosceles reclusa''). Cell physiology Treating cells ...

anticancer agent and antibacterial action against ''

Staphylococcus aureus ''Staphylococcus aureus'' is a Gram-positive spherically shaped bacterium, a member of the Bacillota, and is a usual member of the microbiota of the body, frequently found in the upper respiratory tract and on the skin. It is often positive ...

'' and other

gram-positive In bacteriology, gram-positive bacteria are bacteria that give a positive result in the Gram stain test, which is traditionally used to quickly classify bacteria into two broad categories according to their type of cell wall. Gram-positive bacte ...

pathogens. Determining the biological roles of this pigmented molecule has been of particular interest to researchers, and understanding violacein's function and mechanism of action is relevant to potential applications. Commercial production of violacein and related compounds has proven difficult so improving fermentative yields of violacein is being pursued through

genetic engineering Genetic engineering, also called genetic modification or genetic manipulation, is the modification and manipulation of an organism's genes using technology. It is a set of technologies used to change the genetic makeup of cells, including t ...

and

synthetic biology Synthetic biology (SynBio) is a multidisciplinary area of research that seeks to create new biological parts, devices, and systems, or to redesign systems that are already found in nature. It is a branch of science that encompasses a broad ran ...

Biosynthesis

Antibiotic activity

References

Further reading