Production of laccase isoforms by Pleurotus pulmonarius in response to presence of phenolic and aromatic compounds.

The effect of several phenolic and aromatic monomers structurally-related to lignin on production of laccase by the white rot fungus P. pulmonarius (Fr.) Quélet 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.