英語(yǔ)翻譯
Decolorization of textile dye by Candida albicans isolated from industrial effluents
Vivian Vitor .Carlos Renato Corso
Received:20 March 2008/Accepted:30 July 2008/Published online:20 August 2008 Society for Industrial Microbiology 2008
Abstract The aim of the present work was to observe microbial decolorization and biodegradation of the Direct Violet 51 azo dye by Candida albicans isolated from industrial effluents and study the metabolites formed after egradation.C.albicans was used in the removal of the dye in order to further biosorption and biodegradation at different pHvalues inaqueoussolutions.A comparative study of biodegradation analysis was carried out using UV–vis and FTIR spectroscopy,which revealed significant changes in peak positions when compared to the dye spectrum.Theses changes in dye structure appeared after 72 h at pH 2.50; after 240 h at pH 4.50; and after 280 h at pH 6.50,indicating the different by-products formed during the biodegradation process.Hence,the yeast C.albicans was able to remove the color substance,demonstrating a potential enzymatic capacity to modify the chemical structure of pigments found in industrial effluents.
Keywords Textile dyes .Biodegradation .Decolorization Candida albicans Direct Violet 51 Biosorption
Introduction
Dyes and dyestuff are used in textile,pharmaceutical,leather and cosmetic industries.The main use occurs in textile manufacturing,resulting in wastewater that contains a variety of these pollutants.The release of dyes is a cause of concern due to the effects on the environment and human health [13].A number of these dyes are very stable in the presence of light,water and chemicals.Degradation is used in the bioremediation of these dyes and is an attractive solution due to its lower cost and environmentally friendlier technology when compared to chemical and physical treatment processes [14].
The annual world production of dyestuff amounts to more than 7 9 10 tons [17].It is estimated that 10–15% of the total production of colorants is lost during synthesis and dyeing processes [5].Pigmented industrial effluent is the most obvious indicator of water pollution.The discharge of highly pigmented synthetic dye is not only aesthetically unpleasing,but causes considerable harmful effects when released in bodies of water.Some methods try to solve this problem through the study of decolorization kinetics and the mineralization of reactive azo dyes in aqueous solution through UV/H2O2 oxidation as an appropriate procedure in a textile wastewater pretreatment step [15].However,treatment with biological agents remains the best solution of such a problem.A large number of microorganisms belonging to different taxonomic groups of bacteria,algae,fungi and yeast and have been reported for their ability to decolorize azo dye[10,11,20].
Dye removal by yeast occurs through the physical biosorption of the dye in a non-specific manner to the periphery of the cell,followed by specific accumulation in the wall and interior of the cell.Yeast biomass is an inexpensive,readily available source of biomass that has potential for dye accumulation at lower pH values [4].Candida tropicalis was investigated in the removal of the textile dyes Remazol Blue,Reactive Black and Reactive Red.The results reveal that yeast can bioaccumulate the selected dyes to different extents.Remazol Blue and Reactive Black were bioaccumulated to a greater extent,whereas Reactive Red was bioaccumulated within a more limited range.In the present study,Candida albicans isolated from industrial effluents was used in the removal of the Direct Violet 51 azo dye in order to further biosorption and bio- degradation at different pH values in aqueous solutions.