Technical Note Decolourization of azo dye methyl red by Saccharomyces cerevis MTCC 463 J.P. Jadhav, G.K. Parshetti, S.D. Kalme, S.P. Govindwar * Department of Biochemistry, Shivaji University, Kolhapur 416 004, Maharashtra, India Received 13 May 2006; received in revised form 11 December 2006; accepted 15 December 2006 Available online 9 February 2007 Abstract Saccharomyces cerevisiae MTCC 463 decolourizes toxic azo dye, methylred by degradation process. Methyl red (100 mg l 1 ) is degraded completely within 16 min in plain distilled water under static anoxic condition, at the room temperature. Effect of physico- chemical parameters (pH of medium, composition of medium, concentration of cells, concentration of dye, temperature and on methylred decolourization focused the optimal condition required for decolourization. Biodegradation (fate of metabolism) of methyl red in plain distilled water was found to be pH dependent. Cells of Saccharomyces cerevisiae could degrade methyl r up to 10 cycles in plain distilled water. Analysis of samples extracted with ethyl acetate from decolourized culture flasks in p water (pH 6.5) and at pH 9 using UV–VIS, TLC, HPLC and FTIR confirm biodegradation of methyl red into several different me bolites. A study of the enzymes responsible for the biodegradation of methyl red in the control and cells obtained after deco plain distilled water (pH 6.5) and at pH 9 showed different levels of the activities of laccase, lignin peroxidase, NADH-DCIP re azoreductase, tyrosinase and aminopyrine N-demethylase. A significant increase in the activities of lignin peroxidase and NA reductase was observed in the cells obtained after decolourization in plain distilled water (pH 6.5), however cells obtained at increased activities of azoreductase, tyrosinase, lignin peroxidase and NADH-DCIP reductase. High efficiency to decolourize m in plain distilled water and low requirement of environmental conditions enables this yeast to be used in biological treatmen effluent containing azo dye, methyl red. Ó 2006 Elsevier Ltd. All rights reserved. Keywords:Saccharomyces cerevisiae; Methyl red; Azo dyes; Decolourization; Biodegradation; Yeast; Azoreductase 1. Introduction Large numbers of chemically different dyes are used for various industrial applications and significant proportion appears in the form of wastewater and is spilled into the environment (Meyer,1981).Among these, azo dyesare prominent class of colourants used in tattooing, cosmetics, printing,consumer’s products as well as in textile dying because oftheirchemicalstability and versatility. Their durability howevercausespollution oncethe dyes are released in to the environment. In addition, some azo dyes are toxic and mutagenic (Holme, 1984).Severalphysical and chemical methods have been suggested for the treat- ment of dye contaminated wastewater but not widely used because of the high cost and secondary pollution that can be generated by excessive use of chemicals. In contrast, microbialdegradation of these dyes does not have similar problem so it is necessary to establish biological wastewa- ter treatment of azo dye considering enzymes involved in it. Degradation of azo dye is feasible only if the azo linkage is first cleaved. Saccharomyces cerevisiae cells also showed bioaccumul tion of diazo reactive textile dye (Remazol Blue, Remazol Black B and Remazol Red RB) during the growth in molas- ses (Aksu, 2003).In comparative study on biosorption capacities of differentkinds of dried yeasts for Remazol Blue, Candida lipolytica showed highest dye uptake capacit 0045-6535/$ - see front matter Ó 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.chemosphere.2006.12.087 * Corresponding author. Tel.: +91 231 2609152; fax: +91 231 2691533. E-mail address: spg_biochem@unishivaji.ac.in (S.P. Govindwar). www.elsevier.com/locate/chemosphere Chemosphere 68 (2007) 394–400