Limited studies have been published in the literature about white rot fungal pellets for producing laccase enzyme during repeated-batch mode. The highest laccase activity of growing cells of F. trogii in copper-supplemented agitated and static batch cultures was 4.61 +/-0.88 and 3.12 +/- 0.79 U/ml, respectively. These values were 2.96 +/-0.34 and 2.34 +/- 0.46 U/ml for T. versicolor, in that respect. However, in copper-supplemented repeated-batch cultures of F. trogii and T. versicolor pellets, laccase activity increased to 40.29 +/- 1.97 and 12.09 +/- 0.72 U/ml, respectively. A cumulative total laccase activity of 223 U/ml was determined from seven times recycled pellets from F. trogii. This value for T. versicolor pellets was 59 U/ml. This indicates that repeated-batch method is suitable for long-term laccase activity. Pellets of F. trogii from Cu-supplemented repeated-batch cultures were more effective laccase producers than pellets of T. versicolor. Repeated-batch mode showed excellent performance for laccase production and this method could be an attractive way of stimulating the production of this biotechnologically important enzyme. Copper was used as stimulating agent for the production of laccase which is necessary for laccase synthesis rather than for the activation of preexisting laccase enzyme of these fungi. In addition, Congo Red, Indigo Carmine, Orange II and Remazol Brilliant Blue R dyes could be effectively decolorized by culture filtrates of pellets of these fungi. (c) 2006 Elsevier Inc. All rights reserved.