Your search resulted in 1157 documents. Displaying 25 entries per page.
Effect of acetylation on decay resistance of wood against brown-rot, white-rot and soft-rot fungi
1989 - IRG/WP 3540
Effect of acetylation on decay resistance of wood was investigated using wood blocks of Cryptomeria japonica, Pinus densiflora, Albizia falcata and Fagus crenata. Blocks were treated with uncatalyzed acetic anhydride for different lengths of time and exposed to Tyromyces palustris, Serpula lacrymans, Coriolus versicolor and unsterilized soil. The action of OH-radical on acetylated wood was also examined using Fenton's reagent. The enhancement of decay resistance by acetylation was revealed clearly for all cases of exposures but varying with fungal and wood species used. For a brown-rot fungus Tyromyces palustris, the weight loss reached almost nil in all woods at 20 WPG (weight percent gain) of acetylation, after the striking decrease from 10 to 15 WPG. For a white-rot fungus Coriolus versicolor, it was counted until 12-15 WPG in the perishable hardwoods used, but not in a softwood Cryptomeria japonica, even at 6 WPG. In cases of another brown-rotter Serpula lacrymans and soil burial, effect of acetylation was intermediate between Tyromyces palustris and Coriolus versicolor. Anti-degradation mechanism by acetylation was discussed, from these weight loss - weight gain relationships, and the IR-and 13C-NMR spectral analyses of fungus-exposed wood.
M Takahashi, Y Imamura, M Tanahashi
Questionnaire - Fungal decay types
1985 - IRG/WP 1265
Effects of acetylation on the dimensional stability and decay resistance of kenaf (Hibiscus cannabinus L.) fiberboard
1996 - IRG/WP 96-40059
The objective of this study was to investigate the influence of the acetylation treated kenaf fiber, Phenol formaldehyde resin content level, and three fungi species on the dimensional stability and decay resistance of high density non wood composition boards. A standard ASTM method was used to evaluate weight loss and thickness change. The linear shrinkage and expansion of each species were also determined. All specimens were exposed to decay chambers for 16 weeks. Test results indicated that most of the main factors significantly influence the thickness, length changes, and decay resistance of the high density kenaf fiberboards.
P Chow, T Harp, R Meimban, J A Youngquist, R M Rowell
Physical properties of ß-1,4-Xylanase produced by Postia (=Poria) placenta: Implications for the control of brown rot
1987 - IRG/WP 1318
The degradation of hemicelluloses is an early event in wood decay by brown-rot fungi. An understanding of the physical properties of hemicellulases may suggest target mechanisms for the development of new control agents. Endo-b-1,4-xylanase was partially purified by column chromatography from wood decayed by Postia (= Poria) placenta. The enzyme was extremely resistant to denaturing conditions; no loss of activity was detected after 2 h in 9 M urea or 6 M guanidine-HCl. Boiling the enzyme for 5 min in 2.5% SDS + 0.5% b-mercaptoethanol reduced its activity by 65%, as measured by the production of reducing sugars. The activity of a-D-galactosidase, another enzyme detected in large quantities in the decayed wood, was reduced by 98% under these conditions. Optimum pH and temperature ranges were pH 2-6 and 50-60°C, respectively. The enzyme appears to be a glycoprotein containing 50-60% carbohydrate (w/w); the carbohydrate moiety may protect the enzyme from adverse environmental conditions. The control of brown rot by in situ inactivation of xylanase may not be feasible because of the enzyme's extreme stability.
J A Micales, F Green III, C A Clausen, T L Highley
The dry rot fungus and other fungi in houses. Part 2
1993 - IRG/WP 93-10001
A new concept of oxalic acid biosynthesis in physiology of copper-tolerant brown-rot fungi
2001 - IRG/WP 01-10394
Recently, a wide variety of roles of oxalic acid (oxalate) in wood decay systems have been receiving much attention. Copper tolerance of wood-rotting basidiomycetes has been believed to be due to the detoxification of copper wood preservatives by oxalate produced by these fungi. However, biochemical mechanism of oxalate biosynthesis in relation to physiology of wood-rotting fungi has not been elucidated although two oxalate-forming enzymes, oxaloacetase and glyoxylate dehydrogenase, have been studied in our laboratory. Recently, a new role of glyoxylate cycle in oxalate biosynthesis in wood- rotting fungi has been presented, and the cycle commonly occurred to varying extents among the fungi although they were grown on glucose. Enzymatic analyses showed that isocitrate was cleaved by isocitrate lyase in the glyoxylate cycle rather than oxidized by isocitrate dehydrogenase in tricarboxylic acid (TCA) cycle, and the fungi were found to lack a normal TCA cycle due to the absence of - ketoglutarate dehydrogenase. It is noteworthy that glucose was efficiently converted to oxalate in a theoretical yield of about 80%, accumulating in the culture media of F. palustris. The results further indicate that acetyl-CoA derived from glucose was not completely oxidized to CO2 in TCA cycle but was mainly converted to oxalate with help of the other coupling metabolic cycles, including glyoxylate cycle. Formation of oxalate from several intermediary metabolites using cell-free extracts of F. palustris confirmed that oxalate is also the final product of the metabolic pathway in the in vitro system. Thus, it is proposed as a new concept that most of copper-tolerant brown-rot fungi may acquire the energy by oxidizing glucose to oxalate, i.e. oxalate fermentation expressed in the following equation; Glucose + 5O2 --> 2 Oxalate + 2CO2 + 4H2O.
E Munir, T Hattori, M Shimada
Durability of larch (Larix spp.) wood against brown-rot fungi
1997 - IRG/WP 97-10228
Durability of the heartwood of Larix decidua, L. sibirica, L. gmelinii, L. gmelinii var japonica, L. gmelinii var olgensis and L. sibirica x decidua against brown rot fungi Coniophora puteana, Poria placenta and Gloeophyllum trabeum was tested according to EN 113 test method. Parallel samples were used to study the amount and composition of wood extractives. The sample trees originated from the research forest of Punkaharju Research Station. The average age of the trees was 60 years. In addition, from L. sibirica also trees at 25 and 102 years were used. Results show that the durability of larch is depending on species, age of the tree, the wood part (inner or outer heartwood) and fungus. The average durability of larch heartwood was equal to class 3 or 4 (moderately or slightly durable, according to the standard EN350:2) and comparable with the durability of pine heartwood (Pinus sylvestris L). However, the durability of L. gmelinii var olgensis and L. sibirica (102 years old) was on the higher level than that of the other studied species but the durability varied even within the same board. Also the durability of wood from L. sibirica grown in the Russian side (Siberia) was studied. It was equal to that of the trees grown in Finland. The average amount of resin acids of larch heartwood was only about 0.1% (dry weight). In contrast, the heartwood of scots pine may contain up to 4.0% of resin acids. Resin acids are found to inhibit the linear growth of certain fungi. Interestingly, the largest amounts of resin acids (0.3%) were found in the heartwood of L. gmelinii which also showed high durability. The concentration of water soluble extracts (mainly arabinogalactan) of larch heartwood was quite large, varying between 3.2 - 20.5%. The concentration of water soluble extracts in the heartwood increased along the age of the trees. Lowest level of extractives were found in Larix decidua which was also the least decay resistant species. The durability of wood in different targets and the role of different chemical compounds of larch heartwood on decay resistance needs to be clarified.
H Viitanen, L Paajanen, P Saranpää, P Viitaniemi
Gloeophyllum trabeum and Gloeophyllum abietinum, the most frequent brown rot fungi in fir wood joinery
1999 - IRG/WP 99-10319
In Croatia the primary raw material for joinery production is silver fir wood (Abies alba Mill). L-joints made of home-grown fir sapwood and prepared according to EN 330: 1993 were used to establish the infection and colonisation of micro-organisms, particularly wood decay fungi, to compare the performance of untreated and 1% TnBTO treated L-joints. The L-joints were coated with two types of coat, and 36 months exposed in Zagreb. The first type of coat was alkyd paint and the second was a stain, in three different colours: white, brown, and black. The influence of the preservative, and the type of coat were most important factors which affected the rate of colonisation. The influence of coat colours was significant at the the beginning of exposure. The fastest and the strongest colonisation occurred in untreated L-joints coated with alkyd paint and the lowest colonisation occurred in treated L-joints coated with stain. It was due to the well known vaporous diffusivity of the stains and the low natural permeability of fir sapwood. The most frequently isolated fungi were Gloeophyllum trabeum (Pers.: Fr.) Murr. and Gloeophyllum abietinum (Bull.: Fr.) Karst.
R Despot, M Glavas
The influence of crystalline and amorphous cellulose on extracellular hydrogen peroxide production by brown-rot fungi
1991 - IRG/WP 1482
The production of hydrogen peroxide (H2O2) has been suggested to play a key role in the degradation of wood by wood-rotting fungi. The production of extracellular hydrogen peroxide was studied by a quantitative method which detects the oxidation of the 2,2-azinobis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) by H2O2 and horseradish peroxidase (HRP) in liquid culture medium. The carbon sources used were crystalline and amorphous cellulose. Two brown-rotters, Serpula lacrymans and Poria placenta, were able to produce clearly detectable amounts of extracellular hydrogen peroxide in liquid medium which contained crystalline cellulose as carbon source. No detectable H2O2 was produced in conditions where amorphous medium was used as carbon source. This result suggests that the conformational structure of the substrate may induce H2O2 production by brown-rot fungi.
A-C Ritschkoff, L Viikari
Electron microscopic detection and chemical analysis of three-lamellar structures in wood-destroying fungi
1984 - IRG/WP 1240
In the course of transmission electron microscopical investigations of pine wood decay by various brown- and white-rot fungi extracellular three-lamellar structures (TLS) formed by the fungi were found in specimens stained with ruthenium red. These structures occured in the lumen of the wood cell surrounding the hypha at the outermost layer of the fungal cell wall. In the course of the investigations these structures were also detected in fungi cultivated with glucose on a rotary shaker, where they showed forms similar to tubuli and vesicles. The three-lamellar structures formed by the white-rot fungus Sporotrichum pulverulentum, which were contained in the outermost cell wall layer, were isolated by disintegration of the fungal pellet and subsequent digestion of the fungal cell wall by snail enzyme. It was found that these structures are resistant to the enzymatic digestion and are composed of 80 to 90% carbohydrates, mainly consisting of glucose monomeres, 5 to 10% proteins, containing 5 fractions with molecular weights between 30000 and 200000, and finally 5 to 10% lipids which do not contain any phospholipid.
R Foisner, K Messner, H Stachelberger, M Röhr
Cytochemical localization of hydrogen peroxide in brown rot fungus Tyromyces palustris by cerium chloride technique
1999 - IRG/WP 99-10299
Cerium chloride (CeCl3) was used to localize H2O2 cytochemically for studying relationship between ultrastructural and functional characteristics of cellulose degradation by brown rot fungi. This technique proved very useful in localizing discrete electron-densereactionproducts at high resolution with minimal nonspecific deposition. The cytochemical localization of extracellular H2O2 by CeCl3 using TEM demonstrated the presence of H2O2 within the fungal hyphae. Furthermore, our results give an indication of the diffusion of extarcellular H2O2 from brown-rot decay fungi into the intact wood cell walls in the early stages of decay.
Yoon Soo Kim, Seung-Gon Wi
Some physiological characteristics of a non-degradative strain of Postia (=Poria) placenta
1988 - IRG/WP 1341
The decay capacity of 14 strains of the brown-rot fungus Postia (= Poria) placenta was determined using soil-wood block tests. One isolate was identified as being unable to degrade wood and was determined to be monokaryotic. It retained the ability to produce extracellular carbohydrate-degrading enzymes, although regulation of certain enzymes was atypical under certain cultural conditions. It produced H2O2 and oxalic acid under a variety of carbon and nitrogen regimes, and did not contain double-stranded RNA. It failed to produce large quantities of extracellular polysaccharides in culture. An understanding of the physiology of this isolate would further our knowledge of decay mechanisms leading to safer preservation protocols.
J A Micales, T L Highley
Extracellular layers of wood decay fungi and copper tolerance
1983 - IRG/WP 1180
Extracellular layers around the hyphae of brown, white and soft rot fungi have been examined using electron microscopy. These layers were isolated for identification. Particular interest was directed towards the extracellular layers of copper-tolerant soft rot fungi.
D M Francis, L E Leightley
Decay patterns observed in butylene oxide modified ponderosa pine attacked by Fomitopsis pinicola
1983 - IRG/WP 1183
Small blocks of ponderosa pine chemically modified by butylene oxide to three different weight percent gains (WPG) were decayed for 2 months with the brown rot fungus Fomitopsis pinicola. Wood substance loss and the type of decay pattern recognised were fairly similar both for control and blocks treated to 8 and 15 WPG. No difference in attack was observed between radial or tangential walls in latewood tracheids. Microscopical examination of undecayed wood blocks treated to 23.7 WPG revealed numerous cracks in both the middle lamella regions of radial walls and in cell corners of latewood tracheids. The fungus had gained entry to the cracks, possibly via bordered pits and rays. Attack started from the cracks and progressed along the middle lamella and towards the cell lumen.
T Nilsson, R M Rowell
Non-enzymatic Gloeophyllum trabeum decay mechanisms: Further study
2001 - IRG/WP 01-10395
Information will be presented on the mechanisms involved in, and potential application of, non-enzymatic wood decay by brown rot decay fungi. Specifically, the hypothesized role of low molecular weight phenolate derivatives will be discussed in relation to non-enzymatic degradation of wood. The mechanism of binding of iron by cellulose, and binding and reduction of iron by fungal derivatives and model compounds is examined. Positive and negative aspects of potential application of these compounds in the generation of free radicals will be discussed.
B Goodell, J Jellison
Conditions for basidiospore production in the brown rot fungus Gloeophyllum separium in axenic culture
1984 - IRG/WP 1232
Attempts to control and optimize the production of hymenial structures and basidiospore production in Gloeophyllum sepiarium in axenic culture resulted in the proposal of the following conditions as being suitable. The dikaryotic mycelia originally isolated from basidiocarps could consistently be induced to produce hymenial structures and pure basidiospore collects if illuminated by near ultraviolet light with emission maximum at 355 nm ("black light") at a temperature of 15°C on a chemically defined medium, where the concentration of the carbon and the nitrogen sources were shown to be of critical significance. The necessary conditions for basidiospore production in lignicolous fungi in general are is briefly discussed.
Monographic card: Coniophora puteana (Schum. ex Fr.) Karst. (Second draft)
1978 - IRG/WP 171
Effects of some essential oils on wood destroying organisms
1993 - IRG/WP 93-10047
Three wood destroying fungi: Botryodiplodia theobromae Pat. (stain), Gloeophyllum sepiarium (brown rot), and Pycnoporus sanguineus (white rot) were exposed to six plant essential oils: the peppermint, kaffir lime or leech lime, lavender, tarragon, holy basil, and the eucalyptus. The peppermint oil showed most effective to inhibit fungal growth, while eucalypus oil was the least effective. The other oils inhibition rate varied according to the species of fungi. In the experiment of the powder post beetles Heterobostrychus aequalis Waterh., the insects were killed within three days in the oil of tarragon, eucalyptus and holy basil, while in lavender oil they could live to ten days the same as controls. But on the contrary in the oil of peppermint and kaffir lime, some of them could even lived longer than the controls.
K Atisongkroh, C Anantachoke, P Lekuthai, S Pensook, T Kittirattrakarn
Monographic information on Serpula (Merulius) lacrymans (Schum. ex Fr.) S. F. Gray, according to the 'Model Questionnaire for preparation of monographic cards for wood-destroying fungi'
1978 - IRG/WP 170
J Segmüller, O Wälchli
Oxalic acid production of fifteen brown-rot fungi in copper citrate- treated southern yellow pine
2001 - IRG/WP 01-10388
Non-arsenical copper-based wood preservatives have grown in number since the 1980's as a response to environmental concerns posed by arsenicals. Interest in copper tolerant decay fungi has increased accordingly. Oxalic acid (OA) production by brown-rot fungi has been proposed as one mechanism of copper tolerance. Fifteen brown-rot fungi representing the genera Postia, Wolfiporia, Serpula, Gloeophyllum, Laetiporus, Coniophora, Antrodia, and Tyromyces were evaluated for OA production bi- weekly in southern yellow pine (SYP) blocks treated with 1.2% AI copper citrate (CC). Ten fungi were designated copper tolerant and produced 2 to 17 times more OA in the CC-treated blocks than in untreated SYP after 2 weeks. Weight losses ranged from 20 to 55% in CC-treated SYP after 10 wks. Five fungi were copper-sensitive, producing low levels of OA and low weight losses on CC-treated blocks. In this study, early induction of OA appears to closely correlate with copper tolerance. We conclude that brown-rot fungi able to exceed and maintain an OA concentration of >400 mM in this study effectively decayed SYP treated with copper citrate.
F Green III, C A Clausen
Involvement of hydrogen peroxide in wood decay by brown-rot and white-rot fungi
1985 - IRG/WP 1256
To gain further understanding of the role of H2O2 in wood degradation by brown- and white-rot fungi, we studied the following: (a) extracellular H2O2 production, (b) effect of various hydroxyl radical (·OH) and singlet O2 (1O2) quenching agents on wood and cellulose degradation, (c) intracellular H2O2 production and catalase activity, and (d) cytochemical localization of H2O2 with diaminobenzidine (DAB) during wood degradation. Extracellular H2O2 detection varied with the growth media and chromogen. The chromogen 2,2'-azino-di-(3-ethyl benzthiazoline-6-sulphonic acid) (ABTS) was more sensitive than o-dianisidine. Extracellular H2O2 was not detected in half of the brown-rot fungi. One white-rot fungus did not produce detectable amounts of H2O2. ·OH and 1O2 quenching agents generally did not inhibit decay of wood or decomposition of cellulose by either brown- or white-rot fungi. DAB did not detect the presence of H2O2 within or outside cells of the brown-rot fungus, Poria placenta. Nor was H2O2 -generating activity detected in sonicated extracts of this fungus. With the white-rot fungus, Coriolus versicolor, H2O2 occurred predominantly in the periplasmic space, but also in the cytoplasm and hyphal sheath. Sonicates of Coriolus versicolor contained H2O2 -generating activity. These observations provide further support for H2O2 involvement in degradation of wood by white-rot fungi, but raise doubts concerning its participation in wood degradation by brown-rot fungi.
T L Highley, L L Murmanis
Characterization of glycopeptide from white-, brown- and soft rot fungi
2002 - IRG/WP 02-10424
Extracellular low-molecular-weight substances that catalyze a redox reaction between O2 and electron donors to produce hydroxyl radicals have been isolated from wood degrading cultures of white-rot, brown-rot, and soft-rot fungi. They contained protein, neutral carbohydrate, and Fe(II). These substances were glycosylated (glycated) peptides and suggested to form Amadori product (ketoamine). The glycopeptides are involved in all three types of decay.
H Tanaka, S Itakura, A Enoki
Ibuprofen inhibits in vitro growth of brown-rot fungi
1996 - IRG/WP 96-10160
Ibuprofen, a phenyl propionic acid derivative (2-(4-isobutylphenyl)propionic acid) inhibited growth in vitro of 17 brown-rot fungi at a concentration of 100 µg/mL, while exhibiting no growth inhibition for 8 white-rot fungi at the same concentration. Propionic acid did not inhibit fungal growth in vitro. Morphological changes were noted in fungi that were able to grow in the presence of ibuprofen.
C A Clausen
Monographic information on Serpula incrassata (Berk. and Curt.) Donk
1980 - IRG/WP 1128
J G Palmer, W E Eslyn
Effect of mineral wools on growth and decay capacities of Serpula lacrymans and some other brown-rot fungi
1991 - IRG/WP 1481
The influence of stone wool and glass wool on growth and decay capacities of Serpula lacrymans and some other brown-rot fungi was studied. Mass losses of pine wood caused by Serpula lacrymans and Gloeophyllum trabeum were increased when stone wool was present. Glass wool had no influence on mass losses. Coniophora puteana, Serpula lacrymans and Gloeophyllum trabeum grew into stone wool and destroyed it easily to powder. Poria placenta did not even grow into stone wool to a noticeable degree compared to the other.
L Paajanen, A-C Ritschkoff