Ecology of dye Decolorizing yeasts

Abstract

Textile dyes are among the most recalcitrant pollutants. Industrial effluents containing textile dyes are usually disposed in large amounts into natural water bodies on a daily basis. Their pollution hazard is based on components which may be carcinogenic or toxic to living organisms. Also, because of their marked colour, they affect light penetration, modifying photo-synthetic activity in aquatic environments. Physical and chemical methods may be used for dye removal from industrial effluents. These approaches are expensive, have operational problems and may lead to bigger problems. Several studies have been reported on decolourization of numerous dyes using white rot fungi (WRF). These organisms could mineralize many types of synthetic dyes through their oxidative and non-specific lignonolytic system. However, the strict conditions for enzyme production and the jeopardy of bacterial contamination in non-sterile conditions in dye-containing wastewaters, made difficult the application of white rot fungi for textile dye effluents. Yeasts, on the other hand, have many advantages. Not only because of their fast growth, but also because their ability resist unfavorable environments. Unfortunately, the ecology of dye-degrading yeasts is still poorly understood. In this chapter, we review several methods for textile dye effluent treatment. Then, we focus on dye decolorizing yeast, exploring the still fragmentary information on their ecology, taxonomy and biotechnological applications in the field of textile dyes bioremediation.