Azo dyes are recalcitrant xenobiotic compounds used extensively in textile industries. Textile industries generate and discharge millions of liters of untreated Azo-dye containing effluents in the form of wastewater, which cannot and is not totally degraded by conventional wastewater treatment processes. This, thus causes a serious damage to the environment and needs biological treatment. Degradation of azo dyes being a necessity, diverse dye dumped soils were screened for dye degrading microorganisms especially yeasts. Yeast was only screened as they are efficient degraders and also GRAS organisms. One efficient yeast isolate identified as Saccharomyces sp. which is capable of decolorizing both mono and di-azo dyes was selected, immobilized and studied for azo dye decolourization. The entrapped yeast cells were studied for decolourization of commercially available textile dyes having azo groups. The immobilized yeastâ€™s decolourization abilities were different and varied with different concentrations of carbon and nitrogen sources. The decolourization ranged from 70-100%. Complete decolourization was seen within 12 and 18 hours depending on bead size, number and also the nutrient source. The immobilized beads of size 0.02 cu.sq.mm, numbering 20 for 20ml medium with 106 yeasts cells could be reused efficiently for three cycles. The dye degrading immobilized Saccharomyces isolate could be commercially significant as it is efficiently degrading both mono and di-azo dyes, dye waste waters in a semi-continuous manner and so can be used for industrial effluent treatment.
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