Decolorization of Solophenyl Red 3BL Polyazo Dye by Laccase-Mediator System: Optimization through Response Surface Methodology

Mohamed Neifar,Amel Kamoun,Semia Ellouze-Chaabouni,Raoudha Ellouze-Ghorbel,Atef Jaouani

doi:10.4061/2011/179050

Mohamed Neifar, Amel Kamoun + Show 3 more

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https://doi.org/10.4061/2011/179050

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Journal: Enzyme Research	Publication Date: Aug 2, 2011
Citations: 30	License type: CC BY 3.0

Affiliation: University of Sfax, Tunis University

Abstract

The decolorization of direct Solophenyl red 3BL (SR), a polyazo dye extensively used in textile industry was studied. The Fomes fomentarius laccase alone did not decolorize SR. The natural redox mediator, acetosyringone (AS), was necessary for decolorization to occur. Box-Behnken design was used to evaluate the effects of three parameters, namely, enzyme concentration (0.5–2.5 U mL−1), redox mediator concentration (3–30 μM), and incubation time (1–24 h), on the SR decolorization yield. The fitted mathematical model allowed us to plot response surfaces as well as isoresponse curves and to determine optimal decolorization conditions. The results clearly indicated that the AS concentration was the main factor influencing the SR decolorization yield. The selected optimal conditions were enzyme concentration 0.8 U mL−1, mediator concentration 33 μM, and time 14 h 30 min. These conditions allowed 79.66% of SR decolorization versus 80.70% for the predicted value. These results showed a promising future of applying laccase-AS system for industrial wastewater bioremediation.

Highlights

Waste waters of the textile industries, well implanted in Tunisia, contain considerable amounts of nonfixed dyes and especially of azo dyes
Some fungal laccases as well as laccase mediator systems are efficient in dye decolorization
Preliminary results showed that F. fomentarius laccase did not decolorize Solophenyl red 3BL (SR), indicating that the presence of a mediator is required

Summary

Introduction

Waste waters of the textile industries, well implanted in Tunisia, contain considerable amounts of nonfixed dyes and especially of azo dyes. Some of the dyes cannot be oxidized, or partly oxidized by laccase because they are too large to penetrate into the enzyme active site or have a high redox potential. Laccase mediators, such as 1-hydroxybenzotriazole (HBT), 2,2-azino-bis 3ethylbenzothiaoline-6-sufonic acid (ABTS), and Remazol Brilliant Blue R (RBBR), are found to extend or permit the oxidation of nonspecific substrate by laccase [8, 9]

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