Screening of dye-decolorizing activity of isolated yeasts from the ecoregion of Las Yungas (Tucumán, Argentina).

HIPÓLITO F. PAJOT; JULIA I. FARIÑA; LUCÍA I.C. DE FIGUEROA

Rio de Janeiro

Congreso; 11th Internacional Congress on Yeasts; 2004

International Commission on Yeasts

Synthetic dyestuffs are extensively used in textile, paper, printing industries and dye houses. Effluent discharge from those activities is a cause of health concern and colour removal has become a research topic receiving great attention in water-pollution control. The disposal of dye-containing effluents into receiving waters irreversible damages the environment by affecting photosynthetic activity and generating toxic and/or carcinogenic effects of proper dyes and other auxiliary chemicals. Reactive dyes are typically azo-based chromophores combined with different types of reactive groups e.g. vinyl sulfone, chlorotriazine. They differ from all other classes of dyes in that they bind to the textile fibres, such as cotton, through covalent bonds. They provide certain advantages like bright colour, water fast, simple application techniques with low energy consumption. Dye removal from effluents become difficult since they are stable to light, heat and oxidizing agents. Conventional methods including chemical coagulation/flocculation, ozonation, oxidation or adsorption may achieve certain efficiency in the removal of reactive dyes though their high initial and operational unfortunately restrict their use by dyeing and finishing industries (Aksu et al., 2003). Microbial decolourisation is nowadays seen as a cost-effective method being considered as a promising ‘ecofriendly’ alternative to the conventional techniques. In contrast to the anaerobic microbial processes which may lead to carcinogenic aromatic amines, those involving fungal ligninolytic enzymes with low substrate-specificity become suitable for aerobic dye degradation avoiding thus hazardous product formation. “Yungas Andinas” is the name of the mountain forests in northwest Argentina and South Bolivia. This ecoregion is extremely fascinating from a bio-geographic perspective as it contains what may be the last of the isolated ‘evergreen’ forests resulting from Quaternary glaciations. little is known on the yeast diversity of this area. The aim of this study was to investigate the ability of several yeasts isolated from the unexploited ecoregion of Las Yungas to decolourize commercial azo dyes. To this end, the optimization of a screening and selection scheme was accomplished as described below.