PCR amplified product containing gene responsible for dye decolorization was cloned and expressed in Escherichia coli. The resulting recombinant strain E coli SS125 decolorized 200 mg/l azo dye (Remazol Red) at 30 degrees C at 255 mg cell/l/h, while the host E coli (DH5 alpha) had no color removal ability. The dependence of the decolorization rate on initial dye concentration and the maximum rate occurred with the dye at 100 mg l(-1). The decolorization rate of E coli SS125 was optimal at 37-45 degrees C. Aeration strongly-inhibited the decolorization, but decolorization occurred effectively under static and anaerobic incubation conditions. The E coli SS125 strain also exhibited excellent stability during reported batch operation. (C) 2007 Elsevier Ltd. All rights reserved.