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Keywords:

  • white-rot;
  • soft-rot;
  • peroxidase;
  • peroxygenase;
  • Klason lignin

Abstract

The degradation of lignocellulose and the secretion of extracellular oxidoreductases were investigated in beech-wood (Fagus sylvatica) microcosms using 11 representative fungi of four different ecophysiological and taxonomic groups causing: (1) classic white rot of wood (e.g. Phlebia radiata), (2) ‘nonspecific’ wood rot (e.g. Agrocybe aegerita), (3) white rot of leaf litter (Stropharia rugosoannulata) or (4) soft rot of wood (e.g. Xylaria polymorpha). All strong white rotters produced manganese-oxidizing peroxidases as the key enzymes of ligninolysis (75–2200 mU g−1), whereas lignin peroxidase activity was not detectable in the wood extracts. Interestingly, activities of two recently discovered peroxidases – aromatic peroxygenase and a manganese-independent peroxidase of the DyP-type – were detected in the culture extracts of A. aegerita (up to 125 mU g−1) and Auricularia auricula-judae (up to 400 mU g−1), respectively. The activity of classic peroxidases correlated to some extent with the removal of wood components (e.g. Klason lignin) and the release of small water-soluble fragments (0.5–1.0 kDa) characterized by aromatic constituents. In contrast, laccase activity correlated with the formation of high-molecular mass fragments (30–200 kDa). The differences observed in the degradation patterns allow to distinguish the rot types caused by basidiomycetes and ascomycetes and may be suitable for following the effects of oxidative key enzymes (ligninolytic peroxidases vs. laccases, role of novel peroxidases) during wood decay.