Thermostable laccases produced by a white-rot fungus from Peniophora species

A strain of Peniophora species was shown to produce laccase, which is a new feature for this species. Peniophora secreted several laccase isoforms with pI-values 3.7-4.2 when grown on glucose and soya meal medium. The Peniophora laccases were typical for Basidiomycetes with respect to pH-dependence, specific activity and inhibitors. The interesting exceptional feature of Peniophora laccases was their good thermostability. At 60°C, the half-life of the isoforms in the culture filtrate was approximately 5 h and at 70°C for 15 min. Also, the isolated main isoform with pI-value 4.1 and molecular mass 63 kDa was similarly thermostable. The N-terminal amino acid sequence, altogether 22 amino acid residues, of the separated isoform was 50-63% identical with those of the Basidiomycete laccases analyzed recently.