In the beginning of the white rot decay, the cellulose
macromolecules are mainly left intact, which also gives
the white appearance for the decayed wood. This ability
of white rot fungi is utilised in so called biopulping, i.e.
the fungal pretreatment of wood chips prior to paper
manufacture with intention to reduce the consumption
of electricity or chemicals. Decomposition
of the wood and plant cell wall lignin is possible due to
the fungal production of particular lignin-modifying
enzymes (LMEs), which are extracellular and metalcontaining
oxidoreductases, mainly heme-containing
peroxidases and laccases .
Lignin is the second most abundant biopolymer on
Earth after the plant polysaccharide cellulose . Biological
role of lignin is to strengthen the plant cell walls
by adhesion of the layers of cellulose microfibrils, and
thereby also enhance water transport and resistance to
pathogens . Due to the vast amount (several Gtn)
of lignocellulose annually produced by terrestrial
plants , decomposition of lignin by the white rot
basidiomycetes and their LMEs is essential for cycling
of organic carbon and releasing the more easily degradable
plant polysaccharides available for other microbes.
LMEs are considered to play a crucial role in formation
and modification of the predominantly lignin-derived
humic acids in soils , particularly in forests that
cover ca 30% of Earth’s land surface