A comprehensive review on violacein production by microbial fermentation

Violacein is a natural purple secondary metabolite with a wide range of biological activities including antibacterial, anticancer, antioxidant, and antiparasitic properties, rendering it a highly promising candidate for applications in medicine, agriculture, and food industries. Despite its availability from natural sources, a profound understanding of its production mechanisms has long been lacking. High-level production of violacein has been achieved through integrated strategies, including heterologous expression of its biosynthetic pathway in recombinant strains, enhancement of tryptophan precursor supply, and optimization of fermentation conditions. These approaches offer a flexible and scalable platform for violacein biosynthesis. Furthermore, recent efforts have focused on utilizing agro-industrial waste as a cost-effective and sustainable feedstock to further improve production efficiency and environmental compatibility. This review provides a comprehensive overview of the latest advancements in violacein production, examines the challenges associated with its application, and proposes strategies for optimizing gene expression, refining fermentation protocols, and utilizing low-cost raw materials to facilitate the efficient and sustainable violacein production.