Chapter Four

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2.2 Definition and Biological Role of Saprobic Fungi
The overlapping definition for a saprobe given in Hawksworth et al. (1995)
and Kirk et al. (2001) in the “Dictionary of the Fungi (8 th edition and 9 th edition,
respectively) stated that “a saprobe is an organism that derives its nutrition from the
dead remains of other organisms, e.g. plants and animals, and commonly causes
decay”. The most important role of fungal saprobes is in the decomposer of organic
matter (Table 2.3). Fungi can degrade complex structural materials such as wood and
insect cuticles by producing various enzymes (Techa, 2001), these enzymes are
excreted into the substrate and the mycelium subsequently take-up digested
compounds through their cell wall (de Hoog et al., 2000). Saprobic fungi usually live
on dead vegetable matter (sticks, leaves, logs), as they are the only multi-celled
organisms that can digest both cellulose and lignin, the two major components of
wood (and, in fact, the two major components of plants’ cell walls in general). The
most important saprobic fungi in the ecosystem are basidiomycetes, especially white
rot fungi, but also some of hyphomycetes (e.g Aspergillus fumigatus, Coriolus
versicolor, Gleoporus dichrous, Lentinus edodes, Polyporus abientinus and Polyporus
hirsutus). The degradative ability of saprobic fungi is very important in ecosystems as
they can decay large or small pieces of dead organic matter and enhance humus
synthesis and bring about nutrient cycling.