Yeast-mediated decolorization

In recent years, a growing interest in the research devoted to the biodegradation of azo dyes have been putting in evidence both the feasibility of yeast-mediated decolorization and the metabolic versatility exhibited by yeasts. Taken together, these are very encouraging findings, since the majority of yeast species have never been screened for azo dyes bioremediation. 

Mechanisms of Yeast-Mediated Azo Dyes Decolorization 2.1 Yeast Definition... 

The yeast-mediated enzymatic biodegradation of azo dyes can be accomplished either by reductive reactions or by oxidative reactions. In general, reductive reactions led to cleavage of azo dyes into aromatic amines, which are further mineralized by yeasts. Enzymes putatively involved in this process are NADH-dependent reductases [24] and an azoreductase [16], which is dependent on the extracellular activity of a component of the plasma membrane redox system, identified as a ferric reductase [19]. Recently, significant increase in the activities of NADH-dependent reductase and azoreductase was observed in the cells of Trichosporon beigelii obtained at the end of the decolorization process [25]. 

One of the first reports on yeast-mediated color removal by a putative process of biosorption of azo dyes by yeast (Rhodotorula sp.) biomass belongs to [31]. Yeast species such as Kluveromyces marxianus removed the diazo dye remazol black B [10], Candida catenulata and Candida kefyr removed more than 90% of amaranth by biosorption [6]. Biosorption uptake of the textile azo dyes remazol blue, reactive black, and reactive red by S. cerevisiae and C. tropicalis varied according to the selected dye, dye concentration, and exposure time [5, 7]. In a recent screening work carried out by [32], from the 44 yeast strains tested for their decolorization ability, 12 of them removed the dye Reactive Brilliant Red K-2BP by biosorption, among them the following were identified S. cerevisiae, Saccharomyces uvarum, Torulopsis Candida, and Saccharomycopsis lipolytica. 

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