Enhanced Decolorization of Reactive black 5 by Laccase-Natural Redox Mediator System using Response Surface Methodology

Response surface methodology (RSM) was applied for the decolourization of the azo dye Reactive black 5 (RB-5) using commercial laccase from a white rot fungus Trametes versicolor. It was observed that the presence of syringaldehyde is essential for decolourization of RB-5 because laccase alone did not decolorize the dye. Syringaldehyde (SYD) was found to be an effective natural redox mediator. The effect and interaction of dye, mediator, and enzyme concentration on RB-5 decolorization was evaluated by Response Surface Methodology using Box-Behnken design. Seventeen experiments were conducted as designed by the above design and a quadratic model was obtained for dye decolour-ization through this design. The experimental values were in good agreement with predicted values and the model was highly significant, the correlation coefficient being 0.994. SYD showed main effect on RB-5 decolorization whereas enzyme had low effect. The optimum concentration of dye, enzyme and SYD were found to be 84 µM, 53 mg/L and 150.3 µM, respectively for maximum decolourization (92 %) of the dye. The validation experiment also showed good correlation between experimental and predicted responses.

ISMAT BIBI, HAQ NAWAZ BHATTI, MUHAMMAD ARIF AND ABDUL WADOOD