Enzymatic decolorization and degradation of azo dyes – A review

•Azo dyes are aromatic compounds with one or more –NN– groups.•Synthetic dyes are used in the textile, food, paper, printing, and leather industries.•The release of these dyes into ecosystem has harmful effect on living organisms.•Enzymatic Decolorization and Degradation of Azo Dyes has been proved to be the best option for degradation of these dyes.

Azo dyes are aromatic compounds with one or more –NN– groups. These dyes are the most important and largest class of synthetic dyes used in commercial applications. Several methods have already been used to treat textile effluents including physico-chemical methods such as filtration, carbon activated, coagulation and chemical flocculation. Although these methods are effective, but they are expensive and involve formation of concentrated sludge that creates a secondary disposal problem. In recent years, use of bioremediation based technologies for treating textile wastewater containing dyes has attracted much interest. The ability of microorganisms and their dye degrading enzymes to decolorize and metabolize the dyes has long been known and has proved to be the best option for bioremediation. As far as decolorization and degradation of textile dyes are concerned, azoreductases, laccases, peroxidases and many other important enzymes seem to have shown great potential to decolorize the textile dyes and these enzymes are considered as effective molecular weapon for bioremediation of azo dyes.