Potential and prospects of reductases in azo dye degradation: a review

Synthetic dyes, particularly azo dyes, pose environmental and health risks because of their toxicity and persistence. To reduce these negative effects, it is necessary to degrade and detoxify these dyes into simple, non-toxic substances. Enzymes from various organisms play crucial roles in dye degradation and detoxification, making biological treatments cost-effective and environmentally friendly. Reductases are key players in breaking the azo bonds in azo dyes under limited oxygen conditions. This review emphasizes the importance of reductases in azo dye degradation and the exploration of various organisms that produce these enzymes. Azorereductases and NADH-DCIP reductases have been extensively investigated and have been shown to degrade azo dyes efficiently. These enzymes play key roles in azo dye degradation and detoxification by catalyzing the cleavage of azo linkages in the presence of redox coenzymes, such as NADH, NADPH, and FADH 2 . However, despite their effectiveness, different conditions, such as pH, temperature, dye concentration, and incubation time, affect enzyme activity during degradation; thus, optimization is required for efficient decolorization. Further studies are necessary to identify new species and strains, isolate and characterize enzymes, and determine the possible pathways for degrading azo dyes. • Azo dyes' environmental hazards have attracted researchers' attention. • Reductive enzymes efficiently decolorize azo dyes by breaking the azo bonds. • Several studies have reported the evolvement and potential of reductase in azo dye degradation. • Azoreductase and NADH-DCIP reductase are primary reductases involved in the degradation. • Enzyme activity varies with environmental and growth conditions during dye degradation.