Process Biochemistry 34 (1999) 31 – 37 Decolorization of polymeric dyes by a novel Penicillium isolate Zuoxing Zheng a , Robert E. Levin a , Jennifer L. Pinkham b , Kalidas Shetty a, * a Department of Food Science, Uniersity of Massachusetts, Amherst, MA 01003, USA b Department of Biochemistry and Molecular Biology, Uniersity of Massachusetts, Amherst, MA 01003, USA Received 24 November 1997; received in revised form 9 March 1998; accepted 2 April 1998 Abstract A novel polymeric dye-degrading fungal strain ATCC 74414 was isolated. Taxonomic identification including morphological and cultural characterization indicated that this isolate was a strain of Penicillium. Strain ATCC 74414 aerobically decolorized both Poly R-478 and Poly S-119 in liquid media containing 0.01% of polymeric dyes. The decolorization rate was examined in three distinct liquid media: Schenk and Hildebrandt-K 2 SO 4 medium (SHK), potato dextrose broth (PDB), and half Murashige- Skoog medium (HMS). Strain ATCC 74414 rapidly decolorized R-478 in SHK medium but the color was subsequently released from the mycelial mass into the medium after 2–3 days, indicating that the decolorization in SHK medium could be due to adsorption of Poly R-478 by the mycelia. In contrast, in HMS and PDB media ATCC 74414 decolorized Poly R-478 more steadily, and the dye was initially adsorbed onto the mycelia and was subsequently decolorized without being released into the medium. Strain ATCC 74414 also decolorized Poly S-119 steadily in SHK, HMS and PDB media. It appears that the decolorization process involved initial mycelial adsorption of dye compounds, which was probably followed by biodegradation through microbial metabolism, and the decolorization may be affected by medium constituents. Although aerobic decolorization may not necessarily lead to complete mineralization of dyes, these results have suggested the potential of strain ATCC 74414 in bioremediation of dye-contaminated water and soil. © 1999 Published by Elsevier Science Ltd. All rights reserved. Keywords: decolorization; Penicillium; polymeric dyes 1. Introduction Synthetic dyes are extensively used in textile dyeing, paper printing, color photography, pharmaceutical, food, cosmetic, and other industries [1]. Approximately 10,000 different dyes and pigments are used industri- ally, and over 0.7 million tons of synthetic dyes are produced annually worldwide. It is estimated that 10 – 15% of the dyes are lost in the effluent during such dyeing processes [2]. Major classes of synthetic dyes include azo, anthraquinone, and triarylmethane dyes, and many of them are toxic or even carcinogenic compounds with long turnover times [3]. Therefore, the discharge of highly colored synthetic dye effluents from those industries can result in serious environmental pollution problems. While many physical and chemical methods including adsorption, coagulation, precipitation, filtration, and oxidation have been used for the treatment of dye-con- taining effluents, adsorption is the most widely used method at present due to its convenience and efficiency [4,5]. The most commonly used adsorbent for color removal is activated carbon, but it is relatively expen- sive and the synthetic dyes are not degraded [6]. Biolog- ical methods, being simple to use and low in cost, have been the main focus in recent studies on dye biodegra- dation [7 – 10]. Many synthetic dyes are generally recal- citrant to bacterial degradation [11–13], but more recent studies have demonstrated that many bacteria are able to degrade azo dyes aerobically and anaerobi- cally [7,14 – 17]. Bioremediation of azo dye-contami- nated wastewater has been proposed as a two-step process. The first step required is an anaerobic reduc- tion of the azo bond, resulting in the production of two aromatic amines. An aerobic digestion of the resulting aromatic amines by a mixed bacterial population leads * To whom all correspondence should be addressed. Tel. 1-413- 545-1022; fax: 1-413-545-1262; e-mail: kalidas@foodsci.umass.edu. 0032-9592/99/$ - see front matter © 1999 Published by Elsevier Science Ltd. All rights reserved. PII:S0032-9592(98)00061-2