title: Biodegradation of oak (Quercus alba) wood during growth of the shiitake mushroom (Lentinula edodes): a molecular approach.
abstract: The chemical transformations that occur during growth of the shiitake mushroom (Lentinula edodes) on oak (Quercus alba) were investigated to improve mushroom cultivation and utilization of the spent substrate. Oak logs were decayed by L. edodes over 8 years, during which time they were sampled at six intervals (30, 40, 66, 76, 77, and 101 months). Fresh and decayed oak samples were analyzed using solid-state (13)C NMR and pyrolysis-gas chromatography-mass spectrometry as well as off-line thermochemolysis with tetramethylammonium hydroxide. Degraded oak exhibited lower carbon contents and increased oxygen content compared to the control. Solid-state (13)C NMR analysis revealed that polysaccharides were the major component of both fresh and decayed oak but that L. edodes mediated the preferential loss of cellulose and xylans as compared to lignin, which remained in an altered form. Several trends point toward the degradation of lignin, including a decrease in the proportion of syringyl units as compared to guaiacyl units and a reduction in side-chain length. An increase in guaiacyl and syringyl acid-to-aldehyde ratios occurred with growth, which suggested that the fungus had caused oxidation of Calpha-Cbeta bonds. The overall effect of L. edodes on oak is similar to that of many white-rot fungi, which simultaneously degrade all cell wall components.
authors.affiliation: British Geological Survey, Kingsley Dunham Centre, Keyworth, Nottingham NG12 5GG, United Kingdom. chv@bgs.ac.uk
authors.forename: Christopher H
authors.initials: CH
authors.lastname: Vane
authors.forename: Trevor C
authors.initials: TC
authors.lastname: Drage
authors.forename: Colin E
authors.initials: CE
authors.lastname: Snape
mesh_terms: D002244:Carbon / Q000032:analysis; D002482:Cellulose / Q000032:analysis; D008401:Gas Chromatography-Mass Spectrometry; D006358:Hot Temperature; D008031:Lignin / Q000032:analysis; D009682:Magnetic Resonance Spectroscopy; D010100:Oxygen / Q000032:analysis; D011134:Polysaccharides / Q000032:analysis; D000644:Quaternary Ammonium Compounds / Q000737:chemistry; D029963:Quercus / Q000737:chemistry; D020942:Shiitake Mushrooms / Q000254:growth & development* / Q000378:metabolism; D013997:Time Factors; D014934:Wood; D014990:Xylans / Q000032:analysis
chemical_list: D011134:Polysaccharides; D000644:Quaternary Ammonium Compounds; D014990:Xylans; D002244:Carbon; D002482:Cellulose; D008031:Lignin; C027917:tetramethylammonium; D010100:Oxygen