Biodegradation perspectives of azo dyes by yeasts

Azo dyes are the largest class of synthetic dyes, which are widely used in the textile industry. The amount of dyestuff does not bind to the fibers and is lost in wastewater during textile processing. The discharge of colored effluents into the environment is not only aesthetically unpleasing. Moreover, dyes and their break-down products cause toxic effects and they affect photosynthetic activity of aquatic systems by reducing light penetration. A number of microorganisms belonging to different taxonomic groups of bacteria, algae, fungi and yeast have been reported for their ability to decolorize azo dyes. In the literature the ability to decolorize azo dyes by yeasts, compared to bacterial and fungal species, has been studied in a few reports. Within this review, an attempt is made to elucidate some basic biological aspects associated with the azo dye degradation by yeasts and enzymes involved that are responsible for degradation process.