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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


Removal of heavy metals from treated wood using biological methods
2005 - IRG/WP 05-50226
Heavy metals were removed from wood treated with copper based preservatives using brown-rot fungus Fomitopsis palustris. The amount of effective elements removed by treatment methods was examined. The relationship between oxalic acid concentration and the amount of heavy metals removed from each treated wood was also investigated. The relationship between fungus weight and removal rate was also included. The removal rates of heavy metals were examined at the different mass of chips and different retention rates and different specimen sizes. Effective element removal rate of preservative-treated wood was compared with different cultivation methods. Based on the results of lab-scale experiment, an air lifting bioreactor was employed for its large-scale operation. The efficiency of bioreactor was evaluated.
Dong-won Son, Dong-heub Lee


Decay and termite durabilities of heat-treated wood
2004 - IRG/WP 04-40272
Decay and termite resistances of Plato-treated timbers were evaluated using a modified JIS decay test method, feeding test in a laboratory scale and a field exposure against Reticulitermes speratus (Kolbe) or Coptotermes formosanus Shiraki. The results showed that no significant decay durability of the treated timbers although mass loss from decay slightly decreased in case of treated timbers. Treated alder and birch were drastically fed by termite in a laboratory scale feeding test. Filed trials also showed the same results as the laboratory scale test.
S Doi, K Hanataa, E Kamonji, Yuuji Miyazaki


Preservative ability of wood to be fixed hydroxyl apatite substituted for antimicrobial metals
2001 - IRG/WP 01-30272
We succeeded in forming hydroxy apatite (HAp) in wood. HAp is non-toxicity and safe. Preservative ability of the wood, which substituted one part of Ca of constituent element of this HA p for antibacterial metals was measured. When Ca was substituted for Ag or Zn, mass loss in decay by brown-rot fungus F. palustris was restrained in about 50% (Ag) ~30% (Zn) of value of control specimen. However, when Ca was substituted for Cu, because F. palustris was copper-resistant microorganism, there was hardly the preservative ability. In case of decay by white-rot fungus T. versicolor, when Ca was substituted for Ag or Cu, the preservative ability was shown. In particular high preservative ability was provided when Ca was substituted for Cu + Zn or Ag + Zn. However, there was hardly the preservative ability when Ca was substituted for only Zn.
Y Haruhiko, I Sumaru


Variation of natural durability of sugi (Cryptomeria japonica) wood in 15 clones examined by decay test (Preliminary report)
2004 - IRG/WP 04-10526
Natural durability of wood in 27 trees from 15 clones of sugi (Cryptomeria japonica)  was investigated by an accelerated decay test. Thirty years old trees were collected from a clonal trial in Ibaraki prefecture, Japan. Natural durability is usually evaluated in heartwood. Mass losses of heartwood caused by a brown rot decay fungus, Fomitopsis palustris and a white rot decay fungus, Pycnoporus coccineus were ranged from 0% to 29% and 0% to 14% respectively. The coefficients of their variation among 27 sample trees were 80 % and 38% in mass loss of heartwood by these fungi. Heartwood from one clone was subjected to be low level of mass loss by both fungi. Trees from the clone could be classified into durable. It might be possible to select sugi clones having durable heartwood.
K Yamamoto, A Tamura, R Nakada


Targeted inhibition of wood decay (Using everything but the kitchen sink)
1997 - IRG/WP 97-10203
Low molecular weight oxidative decay agents have been implicated in the degradation of wood by brown-rot decay as evidenced by chemical analysis of brown-rotted wood and detection of oxalic acid and hydroxy radicals. Fenton chemistry (H2O2 / Fe++) is often proposed as the mechanism for generating hydroxy radicals. Previous authors have shown iron to enhance the brown-rot hydrolysis of wood, while others have shown suppression of brown-rot by organic and inorganic metal chelators. We have attempted to inhibit brown-rot and white-rot decay of southern pine and maple wood blocks in a series of soil block decay tests using a variety of chemicals targeted specifically at key components of proposed brown-rot mechanisms. Included in these tests were inorganic and organic chelators, calcium coordinating compounds, wood binding dyes, microbial siderophores and common antioxidants -- some previously tested. All chemicals were screened at 1% aqueous (w/v). Only 2 of 28 compounds were effective in significantly reducing wood weight loss by all fungi tested in 12 weeks: napthaloylhydroxylamine (NHA) -- a calcium precipitating agent; and ruthenium red (RR) -- a pectin stain. Both compounds bind preferentially to pit tori and ray parenchyma cells as observed by light microscopy. Targetting the woody substrate for inhibition of decay looks more promising than targetting fungal physiology
F Green III, T A Kuster, T L Highley


A possible role of unique TCA cycles in wood-rotting basidiomycetes
2003 - IRG/WP 03-10461
The copper tolerant brown-rot fungus, Fomitopsis palustris, acquires metabolic energy by use of the constitutively-occurring Kornberg’s glyoxylate cycle coordinating with oxalate biosynthesis and glucose oxidation (Erman Munir et al. Proc. Natl. Acad. Sci. USA, (2001) 98, 11126-11130). Furthermore, this fungus does not have the normal TCA cycle, lacking 2-oxoglutarate dehydrogenase which is a key ezyme of the TCA cycle of most living things. This paper reports that most wood decay fungi tested lack 2-oxoglutarate dehydrogenase (ODH) and that much greater activities of glutamate dehydrogenase compensating the absence of ODH were detected from both white- and brown-rot fungi.
E Munir, T Hattori, M Shimada


Silicic acid-Boric acid complexes as wood preservatives
2001 - IRG/WP 01-30273
A silicic acid monomer aqueous solution (SAMS) or colloidal silicic acid solution (CSAS) was combined with various metal compounds or boric acid. Agents where SAMS or CSAS was combined with boric acid gave good protection against decay caused by the brown-rot fungus Fomitopsis palustris, the treated wood (Cryptomera japonica D. Don) specimens after the leaching test maintained a high resistance to decay. The leaching and decay tests revealed high quantities of chemicals leaching from wood treated with SAMS-metal agents. However, when wood was treated with SAMS-boric acid, there was little leaching of agent in either test. The mechanism of resistance of wood, which was treated with boric acid mixed with CSAS or SAMS, to the brown-rot fungus F. palustris were investigated. When the concentration of boric acid was high, mycelial growth was inhibited completely and no protein production was detected. When the amount of boric acid was low, the xylanase, mannase and cellulase activities were lower than with control wood powder. When wood was treated with silicic acid only, its resistance to termites increased, but not to the marked extent observed after treatment with a mixture of silicic and boric acids. Also, increasing the quantity of boric acid increased the mortality rate of termites, and shortened the time to death. From field tests on stakes over three years, it was shown that even if stakes were placed near the termite exit, those treated with silicic acid and high levels of boric acid maintained their original form. Combustion tests showed that with high levels of boric acid, flaming and glowing combustion times were shortened. When boric acid-methanol solution was added at of rate of not less than 25 ml for 100 ml of CSAS, flaming and glowing combustion were not observed. Though the charring length of the wood- specimen, which was treated with silicic acid¡boric acid agent, decreased to 1/3 of that of control wood, the charring lengths were not influenced by the level of boric acid. However, the volume of smoke decreased relative to the amount of boric acid that had been added. When powdery boric acid was combined with CSAS, it was considered that the treated woods have higher anti-weather properties than when boric acid-methanol solution was mixed with CSAS. The agent- preparation method adopted should be considered carefully after taking the treatment process and the intended use of the preservative-treated wood into account.
H Yamaguchi


Chemically modified tannin and tannin-copper complexes as preservatives for wood
2001 - IRG/WP 01-30271
The efficacy of Mimosa tannin, chemically modified tannin, and tannin-copper complexes as wood preservatives was studied. When the tannin-ammonia-CuCl2 solutions were impregnated into wood specimens in a one-step procedure, a large quantity of the tannin-copper complex was fixed in the specimens. Little of the complex was leached from specimens by a weathering treatment, and these specimens showed satisfactory decay resistance in a basidiomycete laboratory test according to the Japanese Industrial Standard (JIS) K 1571-1998. Only the tannin-treated wood had a retention of agent after treatment, in increasing order from untreated tannin (MT), resorcinolated tannin (RMT) and catecholated tannin (CMT). When RMT or CMT was mixed with ammonia¡copper, the wood retained twice as much of these solutions as the MT-ammonia-copper solution. The solutions penetrated 2~13mm from the tangential sections of the logs. Presumably, chemical modification increased the degree of retention by altering the structure of the tannin and increasing its hydrophilic properties. The degree of retention of RMT-NH3-Cu and CMT-NH3-Cu in logs with cross-sections ranged from 268 kg/m3 to 326 kg/m3. Wood decay by F. palustris was markedly suppressed by processing wood with agents made by mixing chemically modified tannins with ammonia and cupric chloride. When wood powder was treated with these agents, mycelial growth and generated protein increased to some extent. The preservative effects of the chemically modified tannins (RMT and CMT) or compound agents composed of the tannins and ammonia¡copper were considered to be due to inhibition of the activities of mannase and Cx-cellulase. In the culture medium which treated wood powder was put in with these agents, drop of pH by oxalic acid, which Fomitopsis palustris produces, is not generated. The potency of the effect was thought to be due to chelation of copper, an essential trace element for wood decay by F. palustris, by the tannin, and/or neutralization or suppression of oxalic acid production by ammonia-copper. Also, these active ingredients hindered eating-damage of wood by the termites. However, the mortality of the termites during the eating-damage test (over 21d) did not reach 100% for all active ingredients. The fact that living termites were still present suggests that tannin-ammonia-copper is not perfect for destroying termites.
H Yamaguchi


A physiological role of the glyoxylate and TCA cycles in fruitbody formation of the coppertolerant brown-rot fungus Fomitopsis palustris
2002 - IRG/WP 02-10430
Changes in activity of the representative enzymes involved in biosynthesis of oxalic acid (oxalate) and carbon metabolism of glucose were investigated in relation to the fruit body formation of the copper-tolerant brown-rot fungus Fomitopsis palustris. Changes in specific activities of the two glyoxylate (GLOX) cycle key enzymes (isocitrate lyase (ICL) and malate synthase (MS)), the two oxalate-forming enzymes (oxaloacetase (OXA) and glyoxylate dehydrogenase (GLOXDH)), and a tricarboxylic acid (TCA) cycle enzyme (isocitrate dehydrogenase (IDH)), were measured during the fungal growth. The enzymes for GLOX cycle and oxalate synthesis in mycelia showed greater activities at the stage of mycelial growth than at the fruiting stage. At the fruiting stage, the IDH/ICL activity ratios was reversed, rising from 0.3 to 2.0. Thus, the results obtained indicate that IDH of the TCA cycle plays a more important role than ICL of GLOX cycle for the fruit body formation of F. palustris, whereas ICL is more important than IDH for the oxalate biosynthesis at the earlier satge of the cultivation.
Jeong-Jun Yoon, T Hattori, M Shimada


Sensitivity to Copper of Basidiospores from Copper Tolerant Fungi: Fomitopsis palustris and Oligoporus placentus
2010 - IRG/WP 10-10707
Copper continues to be an important fungicide in wood preservation. It is the primary component of the preservatives that have replaced chromated copper arsenate for treated wood in residential construction in North America. However, a co-biocide is normally needed to protect against copper tolerant organisms. Previous work has shown that the spores of at least one copper tolerant fungus, Oligoporus placentus, were not very tolerant of copper. This explained the unexpectedly good performance of copper-only preservatives when just exposed to spores and not exposed to mycelium of such fungi. This work was designed to determine if the same was true of another copper-tolerant fungus that produces basidiospores in agar culture. An agar medium bio-assay was used to assess inhibition of basidiospore germination and mycelial growth of Fomitopsis palustris (Berk. et Curt) with O. placentus (Fr.) Gilb. & Ryvarden, as a known reference. The spores of F. palustris and O. placentus had the same copper sensitivity. The basidiospores were sensitive to copper concentrations between 20 and 50 times lower than their corresponding mycelium. These data confirm that spores of copper tolerant fungi are not very tolerant of copper.
C S Woo, P I Morris


Biological performance of wood- and bamboo-polypropylene composites: Effects of particle content, particle size and Zn borate
2012 - IRG/WP 12-40577
Particle content and size of wood material in wood plastic composites (WPCs) can affect efficacy of WPCs against fungi and termites. This study evaluated fungal and termite resistance of WPCs manufactured by using two different levels of particle content (50 and 70%) and three different particle sizes (30, 60, and 100 mesh). In fungal resistance tests, Tyromyces palustris, a standardized test fungus, Schizophyllum commune and Pycnoporus coccineus observed previously on commercial WPC products in field tests by various researchers were employed. Termite resistance tests were performed in laboratory conditions using the subterranean termites, Coptotermes formosanus. Mold growth on the WPCs was evaluated in a test period of 4 weeks. In general, WPC specimens containing higher particle content and smaller particle size resulted in increased mass losses in decay resistance tests. As particle content increased, mass losses in the specimens in termite resistance tests increased; however, decreased particle size caused slightly decreased mass losses. The composite specimens along with Zn borate treated specimens were completely colonized by the fungi in a short period of 4 weeks.
S N Kartal, S Aysal, E Terzi, T Yoshimura, K Tsunoda


Characterization of Pectinases from Brown-rot Fungus Fomitopsis palustris
2019 - IRG/WP 19-10951
Brown-rot fungi occur on softwood used as building materials and cause destructive breakdown of wood structure. Therefore, a more accurate understanding is important from the perspective of wood protection. Previous studies have reported that hyphae of brown-rot fungi go through bordered pits on tracheids when the fungi grow into softwood [Francis W.M.R.Schwarze (2007)], and torus existing in the middle of the bordered pits contains pectin abundantly [D. Maschek et al. (2013)]. However, there is a little information on pectin degrading enzymes from brown-rot fungi. In this study, pectinases from brown-rot fungus Fomitopsis palustris were purified and characterized. Fomitopsis palustris was cultivated on the liquid medium containing 2% pectin, and the culture supernatant after the cultivation was recovered by filtration. Proteins in the supernatant were concentrated with 70% saturated (NH4)2SO4, and a polygalacturonase was purified as one of the pectinases by applying to 4 steps of column chromatography. Enzymatic activity was assayed by using sodium polygalacturonate, the main chain of pectin. Purified polygalacturonase was designated as PG-A, and its properties were analysed. Purified PG-A degraded sodium polygalacturonate acting in an endo-like manner. PG-A was not able to degrade calcium polygalacturonate gel that was prepared by mixing sodium polygalacturonate with calcium chloride in distilled water. Pectin in wood is known to be gelling with calcium ions, therefore, PG-A was suggested to degrade pectin in wood in cooperation with other molecules. We presumed that oxalic acid plays an additional role when PG-A degrades pectin in wood. PG-A was found to be able to degrade calcium polygalacturonate gel in the presence of oxalic acid. Moreover, the thermal stability of PG-A was increased in oxalate buffer at pH 3.0 compared to that in phosphate buffer at pH 7.0, which also indicates the importance of oxalate in pectin degradation by PG-A. In addition to calcium polygalacturonate gel, PG-A was unable to degrade methylesterified pectin, which has a similar structure to pectin in wood. We have partially purified pectinmethylesterase from Fomitopsis palustris, and the investigation of the relationship between PG-A and pectinmethylesterase is now under way.
Y Tanaka, N Konno, T Suzuki, N Habu


The evaluation of synergistic effects of chemicals on fungicidal efficacy in crossed-paper tests
1991 - IRG/WP 2383
The mixing effects of wood preservatives were evaluated using the crossed-paper technique. Two filter paper strips (0.7 x 8 cm²) were treated by soaking with different chemicals [fungicides, a termiticide (chlorpyrifos or phoxim), a surface-active agent, a synergistic agent, and a stabilizer], and placed at right angles to each other on a fully grown mycelial mat of a test fungus in a Petri dish. When the four organoiodine fungicides were incorporated with chlorpyrifos or surface active agent, only 3-iodo-2-propynyl butyl carbamate (IPBC) showed the desirable synergistic effect against every wood-decaying fungus tested. Other fungicides did not always tend to produce the synergistic effect with the addition of a surface active agent. 4-Chlorophenyl-3-iodopropargyl formal (IF-1000) appeared to indicate an undesirable antagonistic effect when mixed with either chlorpyrifos or a surface active agent. 3-Bromo-2, 3 diiodo-2-propenylethyl carbamate (EBIP) did not show any synergistic action by mixing with chlorpyrifos and/or a surface active agent, although the fungicidal enhancement was induced satisfactorily by mixing the fungicide with chlorpyrifos, a stabilizer and/or a synergistic agent, especially against Tyromyces palustris and Coriolus versicolor. Similarity of the results obtained in the present investigation and in the previous laboratory decay tests leads to the conclusion that the crossed-paper technique is suitable for the evaluation of the mixing effect of chemicals on fungicidal efficacy.
Dong-heub Lee, K Tsunoda, M Takahashi


A laboratory method for assessing the effectiveness of fungicides in preventing the spread of decay fungi within packages of unseasoned lumber
1983 - IRG/WP 2202
To study the deterioration caused by decay fungi in the laboratory, a method for testing fungicides for their effectiveness in preventing spread of decay was devised. Some experiments using this method are reported here.
A J Cserjesi, E L Johnson, A Byrne


Fungicidal and termiticidal effectiveness of alkylammonium compounds
1983 - IRG/WP 3232
This paper is related to effectiveness of several AAC's against wood decay fungi and termites by Japanese standardized test methods.
K Tsunoda, K Nishimoto


First draft of a monographic card for Fomitopsis pinicola (Fr.) Karst
1980 - IRG/WP 196
P W Perrin


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


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


Studies on the preservation of structrual plywood - Part 1: Decay resistance of structural plywood
1974 - IRG/WP 238
The weight loss and the decreases in the compression strength and in the modulus of elasticity were measured to determine the decay resistance of structural plywood (lauan). Test pieces (50x25xA mm³) were exposed to the wood destroying fungi (Coriolus versicolor and Coriolellus palustris) for 2-3 or 2-4 months. After exposure, the measurement of the compression strength was carried out on the pieces of different thickness (A = 6,12 and 18 mm) and different fibre direction of the face veneer (0°, 45° and 90° to the long side of the test piece). The results obtained were as follows: 1.: The weight loss was small. The greatest weight loss was 9.4% on decaying by Coriolellus palustris for 4 months. 2.: The decreases in the compression strength and in the modulus of elasticity were greater than the weight loss. On decaying by Coriolellus palustris for 4 months, the ratio of decrease of the compression strength was 75% (6 mm - 0°). 3.: For differences of the thickness and of the fibre direction, the weight loss and the decreases the modulus of elasticity in the compression strength and in the modulus of elasticity showed tendencies in order 0° > 45° > 90° and 6 > 12 > 18 mm. 4.: According to the experiment, the face veneer is liable to be easily attacked by the wood destroying fungi, but the decrease in the compression strength was great. So, the face veneer and the cross section should be protected with preservatives for structural use.
K Minami, Y Kenjo, S Sugiyama


Lignin-copper, a new wood preservative without arsenic and chromium
1992 - IRG/WP 92-3702
A more environmentally sound treatment for wood with preservatives containing no arsenic or chromium, has been developed and studied on a laboratory scale. The method involves a first step impregnation with an aqueous solution containing modified, water-soluble kraft lignin followed by a second step involving impregnation with a copper salt solution to give fixation of the lignin into a water-insoluble form and to achieve complementary protection. The two steps can be performed without intermediate drying of the wood in a conventional reactor for vacuum-pressure impregnation. The treatment has been shown to give good protection against degrading fungi, tunnelling bacteria and termites, and a lower growth of mould on the wood surface. Field tests (NTR test) indicate, after 4 years of exposure, very good protection gained by this new treatment. Fibre and particle boards made from wood fibres and wood particles, treated with this method show increased dimensional stability and rot resistance.
B Ohlsson, R Simonson


Protection of Ochroma pyramidale from fungal decay with N,N-napthaloylhyroxylamine
1998 - IRG/WP 98-30182
Fungal decay of wood in service results in billions of dollars (U.S.) in losses annually. Recent environmental restrictions, both U.S. and international, are limiting and eliminating the use of broad-spectrum, heavy metal biocides for wood preservation. Restrictions result primarily from problems with disposal. New wood preservatives need to be developed and tested which specifically target key elements in the sequence of fungal decay mechanisms. Our laboratory has been experimenting with chemicals which inhibit pectin hydrolysis during incipient brown-rot and white-rot decay in southern pine sapwood (Inter. Biodeter. Biodegrad. 39:103). In the present paper these results are extended to include the tropical hardwood Ochroma pyramidale (balsa). Balsa blocks (24x18x12mm) were exposed to two brown-rot fungi and one white-rot fungus in ASTM soil block tests for 10 weeks. CCA (6.4 km/m3 ) was compared with the calcium binding agent N,N-napthaloylhydroxylamine (NHA; 1.6, 3.2 & 6.4 km/m3 ) in leached and unleached blocks. CCA protected balsa with minimal weight loss (> 7.4%) with no leaching effects. NHA (6.4 km/m3 ) protected balsa (0.3-1.2%) weight loss but leaching raised the weight losses to 25% with the brown-rot fungus Tyromyces palustris. We conclude that NHA can protect balsa against G. trabeum and T. versicolor with comparable efficiency to CCA (leached and unleached) but not T. palustris.
F Green III, T L Highley


Immunogold labelling of size marker proteins in brown rot-degraded pine wood
1990 - IRG/WP 1428
Pine wood degraded by Fomitopsis pinicola was infiltrated with a mixture of ovalbumin (45 kDa) and myoglobin (16.7 kDa). After crosslinking of the proteins with glutaraldehyde and preparation for electron microscopy ultrathin sections were labeled with gold-conjugated antibodies. Simultaneous labeling of both proteins on the same section showed that at 50-70% weight loss ovalbumin did not penetrate the brown rot-degraded wood cell walls at all, while partial penetration was observed with myoglobin. Considerable areas of the wood cell walls were not penetrated even by the small myoglobin molecules, although extensive degradation was evident. The results suggest that not only the initial brown rot attack, but all chemical reactions taking place inside the wood cell walls, depolymerization of cellulose to soluble oligosaccharides as well as lignin modification, are caused by a low molecular weight fungal agent.
E Srebotnik, K Messner


Spatial arrangement of lignin peroxidase in pine decayed by Phanerochaete chrysosporium and Fomitopsis pinicola
1988 - IRG/WP 1343
By applying immunoelectronmicroscopic methods, lignin peroxidase of the white rot fungus Phanerochaete chrysosporium has been localized in the cytoplasm of hyphae, close to the plasmalemma and on the plasmalemma. Infiltration of wood specimen with culture filtrates, concentrated 300-fold, gave clear information on the penetration of the enzyme into the wood cell wall. Penetration was restricted to superficial areas. No diffusion of enzymes into the cell wall took place in white rot. Likewise, infiltration of wood. degraded by the brown rot fungus Fomitopsis pinicola, did not indicate free diffusion of the enzyme within the cell wall. This was taken as a proof of non-ezymatic cell wall degradation in brown rot.
E Srebotnik, K Messner


Fungal resistance of smoke-dried Cryptomeria japonica wood
1998 - IRG/WP 98-40118
Performance of smoke dried wood on fungal resistance was studied. The maximum temperature of the smoke seasoning was 80-90°C in the drying room and 70-80°C within the wood for 6 days during the treatment for 15 days. Decay resistance of smoke-dried Cryptomeria japonica wood was evaluated using a brown rot fungus, Tyromyces palustris. Weight losses of untreated wood, smoke-dried wood, and smoke-dried wood followed by surface removal of 3 mm in thickness were 53%, 16%, and 21% respectively. After leaching for ten days, their weight losses were 38%, 51%, and 46% respectively. Smoke-dried wood had decay resistant some extent against the brown rot fungus, however its effectiveness disappeared completely during leaching. Smoke-drying did not have any effect on preventing the mould growth.
K Yamamoto, I Momohara, T Nishimura


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