Bacterial Enzymes and Their Role in Decolorization of Azo Dyes - Microbial Degradation of Synthetic Dyes in Wastewaters - page 145

Bacterial Enzymes and Their Role
in Decolorization of Azo Dyes

Amar A. Telke, Avinash A. Kadam and Sanjay P. Govindwar

1 Introduction

Azo dyes are one of the largest groups of textile dyes, extensively used for dyeing
purposes. A signi cant proportion of these dyes were entering into the surrounding

environment in the form of wastewater. Discharge of such wastewater into natural
water resources has created an aesthetic problem to aquatic life and human being.
Several physico-chemical methods have been employed for azo dye decolorization,
but they have facing several problems, such as generation of toxic by-products and
economical unfeasibility. Several reports have been stated that bacteria, fungi and
plants have ability to decolorize and detoxify azo dyes. However, ubiquitous nature
of bacteria makes them as invaluable tool for the textile dye decolorization. Bac-
terial genera, such as Pseudomonas, Bacillus, Rhodococcus, were reported for rapid
azo dye decolorizing biological agents (Kalyani et al. 2008 ; Telke et al. 2008 ). The
azo dye decolorization by bacteria has been associated with the production of
oxidoreductive enzymes, such as lignin peroxidase (Ghodake et al. 2008 ), laccase
(Telke et al. 2009 ), azoreductases and other non speci

c reductases (Chen et al.
2005 ; Dhanve et al. 2008a , b ). Azo dye decolorization by puri ed bacterial

enzymes was demonstrated in several reports. Previous reviews have indicated that
azo dye decolorization was associated with reductive cleavage of azo bond by