engleski

Enzymatic degradation of stains and dyes

Synthetic dyes used in the textile- or pulp- and paper industry are often harmful or toxic compounds and represent a worldwide ecological problem. In the presented work we aim to develop an eco-friendly, enzymatic approach for dye removal. We investigated 6 different oxidoreductases for their potential to specifically decolorize and detoxify 207 industrially relevant dyes including anthraquinone-, azo-, trimethylmethane-, and indigo chromophores. Utilized enzymes were cellobiose dehydrogenase from the plant-pathogenic fungus Sclerotium rolfsii, laccases from the ascomycete Botrytis aclada and the basidiomycete Trametes pubescens, glucose oxidase from Aspergillus niger, glucose dehydrogenase from Glomerella cingulata and horseradish peroxidase. Decolorization was studied at alkaline, neutral and acidic pH using UV/vis spectroscopy in the 96-well plate format. Absorbances of most of the investigated dyes could be reduced by at least 50% within 24 hours of incubation at room temperature. Highest rates of decolorization were observed at pH 4 for most of the enzymes. Horseradish peroxidase efficiently degraded 79 of the 175 dyes diluted in water (45%) followed by laccase from T. pubescens (27%), laccase from B. aclada (27%), cellobiose dehydrogenase (15%) and glucose dehydrogenase (5.7%). Glucose oxidase (4%) was least successful, indicating that peroxide has little effect on the chromophores. Toxicity of three dyes was investigated using freshwater algae Selenastrum capricornutum. Ongoing research aims to assess the toxicity and chemical structure of the reaction products. Elucidation of the kinetic parameters of the reactions might help to define enzyme mixtures for efficient dye decolorization.

Dye; Decolorization; Enzymes

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