Studies on the Textile Dye Decolorization Ability of Yeasts Isolated from Polluted and non-Polluted Environments in Tucumán, Argentina (poster)

H.F. PAJOT; J.I. FARIÑA; L.I.C. FIGUEROA

Orlando, Florida, USA

Congreso; 106th General Meeting of the American Society for Microbiology; 2006

American Society of Microbiology (ASM)

Background. Effluent discharge from textile and dyestuff industries is a cause of health concern and their treatment has become a current topic of research. Ability for dye decolorization may be expected in microorganisms from dye-polluted sites and also from lignin-degrading microbiota. Methods. Yeasts isolated from textile factory effluents (Maravilla Stream, Tucumán) and from Las Yungas rainforest (Tucumán, Argentina) were compared on their biodecolorization efficiency. Samples from Phoebe porphyria trees and underlying soil were resuspended, plated onto YM-agar and incubated at 26°C. Polluted-site samples were used for 100 mL-microcosms with Normal Decolorization Medium (NDM) plus 200 ppm Vilmafix Blue RR BB, incubated at 250 rpm and 26°C with 20-mg dye pulses at 36 and 72 h. Isolates were confronted to 6 different textile dyes in solid medium. Liquid cultures were examined for dye removal (at dye lopt) and isolates showing higher values were selected. Supernatants, biomass and sonicated fractions were evaluated for dye-peroxidase, laccase, peroxidase, Mn-peroxidase and azoreductase according to standard protocols. Results. Sixty-one and 100 yeast isolates were obtained from Las Yungas and effluent microcosms, respectively. After screening, 5 isolates were selected from each site. Despite isolates from polluted site showed low decolorization on solid medium, they led to the highest dye removal values (~100%) at 36 h. Those from Las Yungas showed higher indexes on solid medium and slightly lower dye removal (~ 95%). Enzyme activities, under the conditions assayed, could not be yet detected in culture or sonication supernatants. However, dye decolorizing activity was found in biomass suspensions (intact cells and cell-walls) at pH 3. Conclusions. These results suggest that the enzymatic activity responsible for dye decolorization may be cell-wall- or membrane associated. Further optimization of enzymatic conditions and/or ultrafiltration steps may lead to the detection of further enzymes or to a better elucidation of the implicated mechanisms on decolorization by the selected yeasts.