The decolorizing capacity of 26 white rot fungi from Argentina was investigated. Extracellular production of ligninolytic enzymes by mycelium growing on solid malt extract/glucose medium supplemented with different dyes (Malachite Green, Azure B, Poly R-478, Anthraquinone Blue, Congo Red and Xylidine), dye decolorization and the relationship between these two processes were studied. Only ten strains decolorized all the dyes, all ten strains produced laccase, lignin peroxidase and manganese peroxidase on solid medium. However, six of the strains could not decolorize any of the dyes; all six strains tested negative for lignin peroxidase, and produced less than 0.05 U/g agar of manganese peroxidase. Comparing the isolates with the well-known dye-degrader Phanerochaete chrysosporium, a new fungus was identified: Coriolus versicolor f. antarcticus, potentially a candidate for use in biodecoloration processes. Eighteen day-old cultures of this fungus were able to decolorize in an hour 28%, 30%, 43%, 88% and 98% of Xylidine (24 mg/l), Poly R-478 (75 mg/l), Remazol Brilliant Blue R (9 mg/l), Malachite Green (6 mg/l) and Indigo Carmine (23 mg/l), respectively. Laccase activity was 0.13 U/ml, but neither lignin peroxidase nor manganese peroxidase were detected in the extracellular fluids for that day of incubation. (C) 2003 Elsevier Ltd. All rights reserved.