For complete decomposition and partial mineralisation
of plant lignocellulose, additional fungal enzymes are
required. On the contrary to cellulose, lignin does not
supply a carbon or energy source for the wood-decaying
fungi [4, 5]. The efficiently lignin-degrading and biopulping
white rot basidiomycetes somewhat decompose cellulose but may as well utilise hemicellulose, thereby
leaving most of the wood cellulose intact [17, 24]. These
fungi typically express multiple MNPs and laccases with
concomitant secretion of organic acids, principally
oxalic acid [38, 139, 140].
The H2O2-producing and quinone-redox-cycling extracellular
enzymes are well justified as additions into
the pool of lignin-modifying enzymes, and are accordingly
listed in the FOLy (Fungal Oxidative Lignin Enzymes)
database (http://foly.esil.univ-mrs.fr) together
with the fungal LMPs and laccases. The novel DyP-type,
heme containing peroxidases [57] may as well participate
in conversion of lignocellulose and lignin, due to
their apparent LMP-like activities, such as oxidation
and bleaching of coloured compounds and potential for
cleavage of lignin substructure linkages, which was
recently demonstrated for a DyP enzyme from the
basidiomycete Auricularia auricula-judae [141].