Journal of Scientific Research and Reports

Violacein is a blue-violet bisindole bacterial pigment whose microbial origin, strong chromophore, and reported antimicrobial activity have encouraged its consideration as a bio-based alternative to petrochemically derived textile colourants. Yet the sustainability and industrial readiness of violacein dyeing remain much less certain than the frequently invoked label of a natural pigment implies. This critical narrative review integrates evidence on violacein biosynthesis, fermentation engineering, textile application, dye-fibre interactions, fastness, functional performance, safety, and process translation. Literature was selected through live searches of multidisciplinary and life-science scholarly sources, with bibliographic identity, retraction status, and digital object identifiers verified before inclusion. The biosynthetic evidence is mechanistically mature: the VioA-VioE enzyme sequence converts L-tryptophan through oxidative coupling, rearrangement, and oxygenation steps, while producer physiology and pathway regulation strongly influence pigment composition and productivity. Production has advanced from native strains to heterologous hosts, fed-batch culture, and agro-industrial feedstocks, but reported titres remain difficult to compare because studies quantify different mixtures of violacein, deoxyviolacein, crude pigment, and purified product. Direct textile evidence is far narrower. Verified studies demonstrate colouration of polyamide, silk, wool, cotton, regenerated cellulose, polyester-containing fabrics, and related substrates, but only a small number quantify colour strength, process variables, fastness, or retained antimicrobial function. Polyamide currently has the strongest integrated evidence, including in-process dyeing during fermentation, whereas proposed molecular interactions with cellulose, protein fibres, and polyester are still based largely on chemical plausibility rather than direct adsorption or spectroscopic proof. Light stability, shade reproducibility, solvent-intensive recovery, leaching, toxicological uncertainty, and absent comparative life-cycle and techno-economic evidence are principal barriers. Violacein is therefore best regarded as a technically credible but conditionally sustainable textile colourant whose industrial case depends on standardised pigment analytics, solvent-minimised process integration, fibre-specific dyeing science, durability testing, safety assessment, and system-level environmental and economic validation.