Study of the sorption-desorption properties of pine wood at the initial stage of decay by wood-rot fungi 10th EWLP, Stockholm, Sweden, August 25–28, 2008

Holzforschung ◽  
2009 ◽  
Vol 63 (6) ◽  
Author(s):  
Jelena Chirkova ◽  
Ilze Irbe ◽  
Ingeborga Andersone ◽  
Bruno Andersons

Abstract Hot water extraction of pine wood was carried out after 10 days of exposure to brown-rot fungi (Gloeophyllum trabeum, Coniophora puteana and Poria placenta) and a white-rot fungus (Coriolus versicolor). The microstructure of the wood cell wall was analysed by the water vapour sorption method. The content and composition of monosaccharides in the extracts were determined by high performance liquid chromatography. Despite the absence of essential mass losses at the initial stage of the contact with the fungi, slight changes in the cell wall microstructure can be observed, namely, the hydrophobisation and the change in the character of porosity in the region of 1–10 nm pore sizes. After hot water treatment, the mass decreases considerably, i.e., to 25% for the control and brown-rot treated samples and more than 30% for the white-rot treated sample. The sorption-desorption isotherms for the washed control sample and brown-rot samples were not changed practically, but the isotherm was changed clearly in the case of the white-rot treated sample. The microstructure of the white-rot sample changed after hot water washing radically and was accompanied with the formation of wide mesopores in the range of 5–9 nm width.

2014 ◽  
Vol 19 (2) ◽  
pp. 323-330
Author(s):  
Zdzisław Tagoński

Studies were carried-out on the ability of 18 strains of 15 white-rot and brown-rot basidiomycetons fungi to degrade wood components and to synthesize cellulolytic enzymes and laccase. 28,5% lignin and 26,1% carbohydrates of pine wood meal, 46,2% lignin and 67,8% carbohydrates of beech wood meal was degraded after 6 weeks incubation by the white-rot fungus <i>Phanerochate chrysosporium</i>. The highest activity of laccase was obtained in from fungi <i>Coriotus zonatus</i> and <i>Fomes fomentarius</i>.


1995 ◽  
Vol 73 (S1) ◽  
pp. 999-1010 ◽  
Author(s):  
Robert A. Blanchette

Degradation of the lignocellulose complex in wood varies depending on the microorganism causing decay. The degradative processes of white-, brown-, and soft-rot fungi as well as different forms of bacterial degradation are presented. Ultrastructural methods were used to elucidate cell-wall alterations that occurred during the various stages of decay. In wood inoculated with the white-rot fungus Ceriporiopsis subvermispora, changes in the cell wall, such as electron-dense zones after staining with uranyl acetate, were evident during incipient stages of decay. The ratio of syringyl:guaiacyl lignin of different woods, different cell types, and even the different layers within a cell wall influenced the type and extent of decay by white-rot fungi. Soft rots caused unique changes in the lignocellulose matrix. The type of wood substrate governed the form (type I or type II) of soft rot that occurred. Brown-rot fungi depolymerized cellulose early in the decay process and degraded cellulose without prior removal of lignin. Bacterial degradation was common in waterlogged woods and three forms, tunneling, erosion and cavitation, are discussed. In addition to an improved understanding of decay processes in living trees and forest products, knowledge of decomposition mechanisms is important to utilize effectively these microorganisms for new industrial bioprocessing technologies. Key words: biodegradation, white rot, brown rot, soft rot, bacterial degradation.


1997 ◽  
Vol 53 (2-3) ◽  
pp. 203-213 ◽  
Author(s):  
Robert A. Blanchette ◽  
Eugene W. Krueger ◽  
John E. Haight ◽  
Masood Akhtar ◽  
Danny E. Akin

Forests ◽  
2020 ◽  
Vol 11 (4) ◽  
pp. 367 ◽  
Author(s):  
Mingming He ◽  
Dandan Xu ◽  
Changgui Li ◽  
Yuzhen Ma ◽  
Xiaohan Dai ◽  
...  

Wood is susceptible to swelling deformation and decay fungi due to moisture adsorption that originates from the dynamic nanopores of the cell wall and the abundant hydroxyl groups in wood components. This study employed as a modifier maleic anhydride (MAn), with the help of acetone as solvent, to diffuse into the wood cell wall, bulk nanopores, and further chemically bond to the hydroxyl groups of wood components, reducing the numbers of free hydroxyl groups and weakening the diffusion of water molecules into the wood cell wall. The derived MAn-bulked wood, compared to the control wood, presented a reduction in water absorptivity (RWA) of ~23% as well as an anti-swelling efficiency (ASE) of ~39% after immersion in water for 228 h, and showed an improvement in decay resistance of 81.42% against white-rot fungus and 69.79% against brown-rot fungus, respectively. The method of combined cell wall bulking and hydroxyl group bonding could effectively improve the dimensional stability and decay resistance with lower doses of modifier, providing a new strategy for wood durability improvement.


Forests ◽  
2019 ◽  
Vol 10 (12) ◽  
pp. 1102 ◽  
Author(s):  
Ladislav Reinprecht ◽  
Miroslav Repák

The European beech (Fagus sylvatica L.) wood was thermally modified in the presence of paraffin at the temperatures of 190 or 210 °C for 1, 2, 3 or 4 h. A significant increase in its resistance to the brown-rot fungus Poria placenta (by 71.4%–98.4%) and the white-rot fungus Trametes versicolor (by 50.1%–99.5%) was observed as a result of all modification modes. However, an increase in the resistance of beech wood surfaces to the mold Aspergillus niger was achieved only under more severe modification regimes taking 4 h at 190 or 210 °C. Water resistance of paraffin-thermally modified beech wood improved—soaking reduced by 30.2%–35.8% and volume swelling by 26.8%–62.9% after 336 h of exposure in water. On the contrary, its mechanical properties worsened—impact bending strength decreased by 17.8%–48.3% and Brinell hardness by 2.4%–63.9%.


1997 ◽  
Vol 45 (5) ◽  
pp. 1911-1915 ◽  
Author(s):  
Robert G. May ◽  
Irene Sparrer ◽  
Enamul Hoque ◽  
Heinrich Sandermann

2019 ◽  
Vol 78 (1) ◽  
pp. 161-171 ◽  
Author(s):  
Michael Altgen ◽  
Suvi Kyyrö ◽  
Olli Paajanen ◽  
Lauri Rautkari

AbstractThe thermal degradation of wood is affected by a number of process parameters, which may also cause variations in the resistance against decay fungi. This study compares changes in the chemical composition, water-related properties and decay resistance of Scots pine sapwood that was either thermally modified (TM) in dry state at elevated temperatures (≥ 185 °C) or treated in pressurized hot water at mild temperatures (≤ 170 °C). The thermal decomposition of easily degradable hemicelluloses reduced the mass loss caused by Rhodonia placenta, and it was suggested that the cumulative mass loss is a better indicator of an actual decay inhibition. Pressurized hot water extraction (HWE) did not improve the decay resistance to the same extent as TM, which was assigned to differences in the wood-water interactions. Cross-linking reactions during TM caused a swelling restraint and an effective reduction in moisture content. This decreased the water-swollen cell wall porosity, which presumably hindered the transport of degradation agents through the cell wall and/or reduced the accessibility of wood constituents for degradation agents. This effect was absent in hot water-extracted wood and strong decay occurred even when most hemicelluloses were already removed during HWE.


Sign in / Sign up

Export Citation Format

Share Document