Highly Efficient Biodecolorization/Degradation of Congo Red and Alizarin Yellow R by Chloroperoxidase from Caldariomyces fumago: Catalytic Mechanism and Degradation Pathway

Chloroperoxidase (CPO) from Caldariomyces fumago could mediate a very efficient oxidative decolorization/degradation of aqueous azo dye. The decolorization efficiencies for Congo Red and Alizarin Yellow R reached 88.25% in 3 min and 92.38% in 5 min, respectively, under mild conditions at enzyme concentrations of 0.025 and 0.03 μmol L –1, respectively. Compared with the typical mechanism involved in oxidative decolorization of azo dyes catalyzed by other peroxidases, a different enzymatic catalytic cycle was found in this work. The oxidative decolorization was carried out in bulk solution, which would get rid of the restriction of substrate required by the channel access to the substrate pocket in the enzymatic active site. Nine degradation products of Congo Red were detected by HPLC–MS analysis, and two types of degradation pathways were proposed accordingly. The strong toleration of the typical salt species in industrial effluents by this system ensured that it has potential applications in treatment of industrial wastewater.