The effect of some activators of manganese-dependent peroxidase (MnP) production, Mn2+, Tween 80, phenylmethylsulphonylfloride (PMSF), oxygen, temperature, pH, and glycerol and nitrogen amount to solid-state cultures of Phanerochaete chrysosporium B KM-F-1767 (ATCC 24725) was studied. Polystyrene foam beads were employed as support material. Supplementing the cultures with Tween 80 (0.05%, v/v) and Mn2+ (174 muM) a maximum MnP activity of 421 U/l was achieved. This value was approximately two times higher than that obtained in the control cultures (without Tween 80). Decolorization of some azo dyes was also achieved with MnP that produced in solid-state culture of R chrysosporium. (C) 2003 Elsevier Ltd. All rights reserved.