Studies On Immobilized Yeast For Decolorization Of Azo Dyes

Abstract Azo dyes that are extensively used in textile industries are recalcitrant xenobiotic compounds causing a serious damage to the environment. Degradation of azo dyes being a necessity diverse dye dumped soils were screened for dye degrading yeasts. One efficient yeast isolate capable of decolorizing both mono-azo dyes and di-azo dyes was selected immobilized by entrapment method and studied for decolorization efficiency. The isolate was morphologically culturally and biochemically identified as Saccharomyces sp. Sodium alginate entrapped yeast cells were studied for decolorization of commercially available textile dyes having azo groups. The extent of colour removal in the culture medium was assessed through the decrease in dye absorbance of the supernatants. The immobilized yeasts decolorization abilities were different and varied with inoculum size incubation time and nutrients like carbon and nitrogen sources. The fermentation conditions like pH temperature and aeration had no profound effect. The decolorization ranged from 70-100. Complete decolorization was seen within 12 and 18 hrs depending on inoculum size. The immobilized beads with yeasts could be reused efficiently for three cycles. The dye degrading immobilized Saccharomyces isolate could be commercially significant as it is efficiently degrading both mono-azo and di-azo dyes different dye waste waters in a semi-continuous manner and so could also be used for detoxification of industrial effluents.