title: Characterisation of the initial degradation stage of Scots pine (Pinus sylvestris L.) sapwood after attack by brown-rot fungus Coniophora puteana.
abstract: In our study, early period degradation (10 days) of Scots pine (Pinus sylvestris L.) sapwood by the brown-rot fungus Coniophora puteana (Schum.: Fr.) Karst. (BAM Ebw.15) was followed at the wood chemical composition and ultrastructure-level, and highlighted the generation of reactive oxygen species (ROS). An advanced decay period of 50 days was chosen for comparison of the degradation dynamics. Scanning UV microspectrophotometry (UMSP) analyses of lignin distribution in wood cells revealed that the linkages of lignin and polysaccharides were already disrupted in the early period of fungal attack. An increase in the lignin absorption A(280) value from 0.24 (control) to 0.44 in decayed wood was attributed to its oxidative modification which has been proposed to be generated by Fenton reaction derived ROS. The wood weight loss in the initial degradation period was 2%, whilst cellulose and lignin content decreased by 6.7% and 1%, respectively. Lignin methoxyl (-OCH3) content decreased from 15.1% (control) to 14.2% in decayed wood. Diffuse reflectance Fourier-transform infrared (DRIFT) spectroscopy corroborated the moderate loss in the hemicellulose and lignin degradation accompanying degradation. Electron paramagnetic resonance spectra and spin trapping confirmed the generation of ROS, such as hydroxyl radicals (HO∙), in the early wood degradation period. Our results showed that irreversible changes in wood structure started immediately after wood colonisation by fungal hyphae and the results generated here will assist in the understanding of the biochemical mechanisms of wood biodegradation by brown-rot fungi with the ultimate aim of developing novel wood protection methods.
authors.affiliation: Latvian State Institute of Wood Chemistry, Dzerbenes Str. 27, Riga, LV-1006, Latvia. ilzeirbe@edi.lv
authors.forename: Ilze
authors.initials: I
authors.lastname: Irbe
authors.forename: Ingeborga
authors.initials: I
authors.lastname: Andersone
authors.forename: Bruno
authors.initials: B
authors.lastname: Andersons
authors.forename: Guna
authors.initials: G
authors.lastname: Noldt
authors.forename: Tatiana
authors.initials: T
authors.lastname: Dizhbite
authors.forename: Nina
authors.initials: N
authors.lastname: Kurnosova
authors.forename: Mari
authors.initials: M
authors.lastname: Nuopponen
authors.forename: Derek
authors.initials: D
authors.lastname: Stewart
mesh_terms: D000935:Antifungal Agents / Q000138:chemical synthesis; D001487:Basidiomycota / Q000378:metabolism*; D001673:Biodegradation, Environmental; D002473:Cell Wall / Q000378:metabolism; D004578:Electron Spin Resonance Spectroscopy; D017665:Hydroxyl Radical / Q000378:metabolism; D008031:Lignin / Q000378:metabolism*; D041605:Pinus sylvestris / Q000378:metabolism* / Q000382:microbiology; D011134:Polysaccharides / Q000378:metabolism; D013056:Spectrophotometry, Ultraviolet; D017550:Spectroscopy, Fourier Transform Infrared; D014934:Wood / Q000378:metabolism* / Q000382:microbiology
chemical_list: D000935:Antifungal Agents; D011134:Polysaccharides; D017665:Hydroxyl Radical; C007916:hemicellulose; D008031:Lignin