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A solid-state system to obtain rapid in vivo industrial dye decolourisation by the white-rot fungus Pleurotus pulmonarius is proposed. When cultivated on glucose\ammonium tartrate–corncob solid-state medium, P. pulmonarius decolourised structurally different synthetic dyes (including azo, triphenylmethane, heterocyclic and polymeric dyes). Amido black, congo red, trypan blue, methyl green, remazol brilliant blue R (RBB), methyl violet, ethyl violet and brilliant cresyl blue were completely decolourised after 6 days of cultivation, while methylene blue and Poly R-478 were partially decolourised. The capability of fungal culture to decolourise industrial dyes appears to be due to high titres of laccase (480 U/ml) produced in response to the presence of soluble phenolics.

The effect of several phenolic and aromatic monomers structurally-related to lignin on production of laccase by the white rot fungus P. pulmonarius (Fr.) Quelet has been studied. In the absence of an inducer, laccase was maximally produced after depletion of carbon and nitrogen sources. Among 15 phenolic and aromatic compounds tested, ferulic acid and vanillin were the most efficient inducers, increasing the production of laccase activity up to 10 times. A mixture of ferulic acid and vanillin was more efficient to induce the production of laccase than the isolated phenolics. At least three laccase isoforms designated as lcc1, lcc2 and lcc3 were identified by eletrophoretic analysis of P. pulmonarius culture filtrates. The lcc1 and lcc2 isoforms were produced by non-induced cultures, while lcc3 was found only in induced-culture filtrates.