Improved conditions for the aerobic reductive decolourisation of azo dyes by Candida zeylanoides

A number of anaerobic and aerobic bacterial species are known to decolourise azo dyes through the reduction of the azo bonds, forming the corresponding amines. In this work, we describe improved decolourisation conditions for model azo dyes by the ascomycete yeast Candida zeylanoides. The dyes were...

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Bibliographic Details
Published in:	Enzyme and microbial technology Vol. 31; no. 6; pp. 848 - 854
Main Authors:	Ramalho, Patricia A, Scholze, H, Cardoso, M.Helena, Ramalho, M.Teresa, Oliveira-Campos, A.M
Format:	Journal Article
Language:	English
Published:	Amsterdam Elsevier Inc 01-11-2002 Elsevier Science
Subjects:	Ascomycetes Azo dyes Biological and medical sciences Biological treatment of waters Biotechnology Candida zeylanoides Decolourisation Environment and pollution Fundamental and applied biological sciences. Psychology Industrial applications and implications. Economical aspects Methyl orange Orange II Yeasts Yeasts Decolourisation Methyl orange Azo dyes Orange II Candida zeylanoides Discoloration Aerobiosis Yeast Biological purification Fungi Azo dye Fungi Imperfecti Waste water purification Thallophyta
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Summary:	A number of anaerobic and aerobic bacterial species are known to decolourise azo dyes through the reduction of the azo bonds, forming the corresponding amines. In this work, we describe improved decolourisation conditions for model azo dyes by the ascomycete yeast Candida zeylanoides. The dyes were derived from the diazonium salts of metanilic and sulfanilic acids and N, N-dimethylaniline or 2-naphthol as coupling components. Total decolourisation times observed in culture media supplemented with 0.2 mM dye ranged from 40 to 60 h. The initial decolourisation rates were 14–52 μmol (g dry cell) −1 h −1, depending on dye structure. In the course of decolourisation either metanilic acid or sulfanilic acid were detected in the supernatant fluid, showing that decolourization by this yeast strain is due to azo bond reduction. None of those aminobenzenesulfonates supported microorganism growth as carbon and energy source but both could be used, to a limited extent, as nitrogen sources. The azo reductase activity is not significantly affected by pre-adaptation of the microorganism to the dyes.
Bibliography:	ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23
ISSN:	0141-0229 1879-0909
DOI:	10.1016/S0141-0229(02)00189-8