Decolorizing kinetics of a recombinant Escherichia coli SS125 strain harboring azoreductase gene from Bacillus latrosporus RRK1

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.