Introduction

Fungi are the main decomposers of dead plant material and many fungal species are known as plant pathogens. Saprophytic fungi are able to get energy and nutrients from a large variety of organic compounds and therefore they are found in practically all terrestrial habitats in which there is life. Fungi can colonize new locations efficiently by spreading through their spores. A saprophytic fungus is always competing for nutrients against bacteria and other fungal species in its habitat. In many cases fungi benefit from their ability to degrade complex plant polymers more completely than bacteria and they also compete by antagonism against other saprophytic microbes. Yeasts are not generally able to decompose plant cell walls with polymeric components and thus saprophytic fungi are mainly filamentous. Saprophytic fungal species can be found in all fungal classes.

The saprophytic fungi are divided into three groups according to their mode of action on plant material. Soft-rot fungi cause softening of wood, degrading preferably plant polysaccharides but are often capable of slow lignin degradation as well. These species mostly belong to Ascomycetes. Brown-rot fungi degrade plant polysaccharides and leave behind a brown, modified lignin residue. White-rot fungi invade the lumens of wood cells and cause progressive thinning of the cell wall. They can degrade both plant polysaccharides and lignin efficiently. The members of the two latter groups mostly belong to Basidiomycetes.