|
A wood-decay fungus is a variety of fungus that digests moist wood, causing it to rot. Some species of wood-decay fungi attack dead wood, such as brown rot, and some, such as ''Armillaria'' (honey fungus), are parasitic and colonize living trees. Fungi that not only grow on wood but actually cause it to decay, are called lignicolous fungi. Various lignicolous fungi consume wood in various ways; for example, some attack the carbohydrates in wood and some others decay lignin. The rate of decay of wooden materials in various climates can be estimated by empirical models.〔Viitanen, T. et al. (2010). Towards modelling of decay risk of wooden materials. European Journal of Wood and Wood Products 68:303-313.〕 Wood-decay fungi can be classified according to the type of decay that they cause. The best-known types are brown rot, soft rot, and white rot.〔〔 Each produce different enzymes, can degrade different plant materials, and can colonise different environmental niches.〔Vane, C. H., et al. (2005). "Decay of cultivated apricot wood (Prunus armeniaca) by the ascomycete Hypocrea sulphurea, using solid state 13C NMR and off-line TMAH thermochemolysis with GC–MS." International Biodeterioration & Biodegradation 55(3): 175-185.〕 The residual products of decomposition from fungal action have variable pH, solubility and redox potentials. Over time this residue will become incorporated in the soil and sediment, so can have a noticeable effect on the environment of that area.〔 ==Brown rot== Brown-rot fungi break down hemicellulose and cellulose. Cellulose is broken down by hydrogen peroxide (H2O2) that is produced during the breakdown of hemicellulose.〔 Because hydrogen peroxide is a small molecule, it can diffuse rapidly through the wood, leading to a decay that is not confined to the direct surroundings of the fungal hyphae. As a result of this type of decay, the wood shrinks, shows a brown discoloration, and cracks into roughly cubical pieces; hence the name ''brown rot'' or ''cubical brown rot''. Brown rot in a dry, crumbly condition is sometimes incorrectly referred to as ''dry rot'' in general. The term ''brown rot'' replaced the general use of the term ''dry rot'', as wood must be damp to decay, although it may become dry later. Dry rot is a generic name for certain species of brown-rot fungus. Brown-rot fungi of particular economic importance include ''Serpula lacrymans'' (true dry rot), ''Fibroporia vaillantii'' (mine fungus), and ''Coniophora puteana'' (cellar fungus), which may attack timber in buildings. Other brown-rot fungi include the sulfur shelf, ''Phaeolus schweinitzii'', and ''Fomitopsis pinicola''.〔 Brown-rot fungal decay is characterised by extensive demethylation of lignins whereas white-rot tends to produce low yields of molecules with demethylated functional groups.〔Vane, C. H., et al. (2001). "The effect of fungal decay (Agaricus bisporus) on wheat straw lignin using pyrolysis–GC–MS in the presence of tetramethylammonium hydroxide (TMAH)." Journal of Analytical and Applied Pyrolysis 60(1): 69-78.〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Wood-decay fungus」の詳細全文を読む スポンサード リンク
|