The effect of anthraquinone-2-sulfonate covalently immobilized in PUF (AQS-PUF) on the decolorization of azo dyes by Escherichia coil K12 was investigated The results showed that AQS-PUF mediated biodecolorization rate of azo dye amaranth increased over 5-fold compared with that lacking AQS, and the kinetics of its biodecolorization could be described using Quiroga second order equation During the above process, a lot of the cells of E colt K12 were attached in the walls of AQS-PUF pores After 10 repeated experiments using AQS-PUF, immobilized AQS-mediated biodecolorization efficiency of amaranth retained over 98.7% of their original value. Moreover, AQS-PUF could greatly enhance the decolorization rates of a broad range of azo dyes These results indicated that AQS-PUF as a biocarrier exhibited high catalytic activity and good stability for potential applications (C) 2010 Elsevier Ltd. All rights reserved.