Decolorization of an azo dye, Reactive Black 5 and MnP production by yeast isolate: Debaryomyces polymorphus

The optimum conditions for decolorization of an azo dye, C.I. Reactive Black 5 (RB5) and the kinetic characteristics of manganese-dependent peroxidase (MnP) production by yeast isolate, Debaryomyces polymorphus, were investigated. D. polymorphus could completely degrade 200 mg l−1 of non-hydrolyzed and hydrolyzed C.I. Reactive Black 5 within 24 h of cultivation at an inoculum size of 1.4 g l−1 wet cells in 50 ml medium consisting of 5 g l−1 glucose and 0.5-1.0 g l−1 ammonium sulphate (pH 5-7). In addition, the MnP activities during the cultivation were evaluated in the absence and presence of 200 mg l−1C.I. Reactive Black 5. Maximum activity of MnP (1555.6 U l−1) was detected at 24 h cultivation in the presence of the dye, and a significant reduction of the enzyme activity was observed thereafter. The presence of C.I. Reactive Black 5 in the culture was found to be indispensable to the production of MnP by D. polymorphus. A good correlation was found between the dye degradation and the enzyme production.