Microbial Violacein as a Sustainable Pigment for Textile Dyeing: Biosynthesis, Dye–Fiber Interactions, and Industrial Perspectives

Environmental concerns regarding the persistence and toxicity of synthetic colourants have stimulated increasing interest in sustainable bio-based pigments for textile applications. Among emerging alternatives, violacein, a purple indole-derived pigment produced by several bacterial species, has attracted considerable attention due to its intense colouration, molecular stability, and intrinsic antimicrobial and antioxidant properties. This review provides a comprehensive analysis of recent advances in violacein research, with particular emphasis on its applicability in textile dyeing and functional fabrics. Developments in microbial biosynthesis, extraction, and purification strategies are discussed alongside reported dyeing performance on both natural and synthetic fibres. Key parameters including dye–fibre interactions, colour strength, fastness properties, and process optimisation are evaluated to assess material performance and industrial relevance. The environmental implications of violacein-based dyeing systems are also analysed within the context of sustainable textile production. Challenges associated with large-scale microbial production, pigment standardisation, regulatory constraints, and economic feasibility are critically discussed. Finally, emerging market perspectives and future research directions are highlighted. Overall, violacein is presented as a promising bio-based pigment with significant potential to contribute to sustainable textile colouration and multifunctional material development.