Discoloration of indigo dyes by eco-friendly biocatalysts

Abstract

Indigo is one of the most commonly used dyes worldwide. However, indigo dyeing technology and physicochemical treatment processes have generated potentially hazardous by-products and sludge, causing serious environmental pollution. Among indigo-treating technologies, biological treatments using a “green” catalysts of laccase and oxidase enzymes have been spotlighted. This review comprehensively assessed the whole cell-based discoloration and in vitro enzyme treatment of indigo (carmine) and process engineering, including enzyme immobilization and aggregation, for indigo degradation. Although both have various advantages, effective process design to obtain desirable biomass and enzyme production strategy with cost-effective manner should be considered for indigoids treatment. In addition, the supply of electron mediators and the removal of unexpected byproducts by the laccase should also be considered throughout the whole process. Therefore, further researches on enzyme and process engineering such as chemo-enzymatic process to obtain the desired performances at the industrial level were suggested.