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Targeted inhibition of wood decay fungi: degradation of cotton cellulose
1999 - IRG/WP 99-10321
Brown-rot decay is responsible for 80% of the damage and replacement of wood in service. For nearly thirty years, researchers have postulated a one-electron oxidase system combining Fe+2 oxalic acid, and H2O2 in the production of hydroxy radicals which ultimately oxidize cellulose in situ. Recently, researchers have been investigating antioxicants, in combination with biocides (Schultz, et al.,1998), as targeted inhibitors of the decay process and potential wood preservatives. In order to target the cellulolytic mechanisms of brown-rot and white-rot decay fungi, cotton cellulose was treated with free radical scavengers, antioxidants, dyes and hydroxy-radical detectors 2,2'-Azino-bis (3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) in order to assess their ability to retard cellulose hydrolysis. Weight loss of cotton cellulose is the most reliable and accurate measure of exoglucanase activity. Cotton cellulose was exposed to G. trabeum MAD 617, T. palustris 6137 and T. versicolor MAD 697 in soil-block tests. After 12 weeks exposure, cotton was evaluated for weight loss, change in DP, and elemental analysis by ICP spectroscopy. Only 2 out of 11 compounds tested (NHA and ruthenium red) showed less than 1% weight loss for all three fungi tested. All other compounds were selective, underscoring difficulties in sharply targeting decay mechanisms. Weight loss and DP of cellulose are analogous to degradation and strength loss of wood caused by decay fungi.
F Green III, T A Kuster


Reactivity of alkoxysilanes with cellulose and lignin in presence of catalysts
2018 - IRG/WP 18-40831
The origin of research was another step in development of a new conservation method for wood cultural heritage. Wood silanisation seemed to be an alternative method to waterlogged wood PEG treatment. The superior aim from the practical point of view was to increase dimensional stability and reduce the hygroscopicity of archaeological wood. The aim of the study was to identify interactions between wood main components and selected alkoxysilanes. Celullose and lignin were modified with alkoxysilanes in presence of catalysts. The scope included methyltrimethoxysilane (MTMOS) and methyltriethoxysilane (TEMS) as modifying agents. Aluminium acetylacetonate (Al(acac)3) and acetic acid (AcOH) were used as catalysts. Samples were measured by using FT-IR. It turned out that cellulose was not so readily reactive to alkoxysilanes as lignin. However, cellulose can react with silanols, which are the product of hydrolysis of alkoxysilanes. For this purpose, catalysts were used to enhance the durability of the interactions between alkoxysilanes and wood main components. In case of lignin, no catalyst addition was needed. In case of cellulose, results clearly showed better reactivity of alkoxysialnes in the presence of catalysts. These results are confirmed by peaks on spectra appeared at e.g. 1270 cm-1 and 777 cm-1. Depending on the formulations the intensity of peaks were different between each other. They corresponded to the Si-CH3 groups. In the case of lignin, peak at 920 cm-1 corresponded to Si-OH bonds which proved that hydrolysis was occurred.
J Siuda, W Perdoch, B Mazela, M Zborowska


Leaching of components from water-borne paints and fungitoxic effects
1995 - IRG/WP 95-20062
Water-borne model paints, acrylics and alkyd emulsion paints, of known composition were leached according to a procedure modified in accordance with ASTM 6271.1. The effectiveness of fungicidal compounds in the painted specimens before and after leaching was evaluated with a biotest in which Penicillium brevicompactum was used as a test fungus. The leaching of the fungicide Troysan Polyphase according to the biotest varied to a high extent depending on differences in paint composition. Fungicide efficiency in relation to paint formulation and fungicide mobility in a paint film is briefly discussed.
J Bjurman


Response of the Formosan Subterranean Termite (Coptotermes formosanus) to Cellulose Insulation Treated with Boric Acid in Choice and No-Choice Tests.
2004 - IRG/WP 04-10532
The tunneling ability of the Formosan subterranean termite Coptotermes formosanus Shiraki through a cellulose insulation material containing11.1% boric acid was tested in choice and no-choice bioassays. We examined tunneling behavior and mortality of termites exposed to treated and untreated insulation material in miniature simulated wall voids. In a choice test termites tunneled through untreated insulation in all but one of the replicates used. Termites were unable to fully penetrate any of the replicates containing treated insulation and experienced a significantly higher mortality (78.4 ± 18.4%) than termites exposed to untreated insulation (11.6 ± 5.6%, F = 60.4, df = 1, P < 0.0001). In a no- choice test termites fully penetrated all replicates containing untreated insulation and experienced 37.1 ± 37.2% mortality. Termites exposed to treated insulation in this test experienced a significantly higher mortality of 100.0% (F = 14.3, df = 1, P < 0.005), and did not fully penetrate the treated insulation.
M E Mankowski, J K Grace


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


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


A discussion of current theories concerning CCA fixation
1983 - IRG/WP 3238
The understanding of the fixation mechanism of CCA and related preservatives in wood has been greatly improved by a significant series of recent scientific papers. In view of recent concerns in New Zealand regarding the long-term efficacy of CCA in high decay-hazard situations, it was considered appropriate to review this recent work and to contrast it with theories presented by previous workers.
D V Plackett


Contribution of wood components on the absorption of copper amine
2000 - IRG/WP 00-30216
The contribution of wood components on the absorption of copper amine was investigated. Holocellulose, lignin and xylan absorbed significant amount of copper. The amount of copper absorbed by cellulose was almost negligible. The removal of extractive also decreased the amount of copper absorption. This study clearly indicates the importance of lignin, hemicellulose in the absorption of copper amine in wood.
D P Kamdem, Jun Zhang


Defining fungal decay types - Final proposal
1988 - IRG/WP 1355
The term soft rot is proposed for all forms of decay caused by Ascomycetes and non-basidiomyceteous Fungi imperfecti. The terms brown rot and white rot should be used only for decay caused by Basidiomycetes. Brown rot is characterized by extensive depolymerization of the cellulose and limited lignin degradation. White rot is characterised by significant degradation of the lignin component in wood.
T Nilsson


The potential for accelerated ageing to determine the persistence of active ingredients in timber
2006 - IRG/WP 06-20323
Fast screening methods for evaluating the persistence of active ingredients in timber are proposed. This is an outline proposal which is intended to provoke discussion and further development of the methods. Reliable and accurate analytical methods are key to these tests.
L D A Saunders, M R Powell


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


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


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&apos;-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


A novel defaunation method of the protozoa to investigate cellulose metabolism in Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae)
1994 - IRG/WP 94-10050
The largest protozoa in the hindgut of workers of Formosan subterranean termite, Coptotermes formosanus Shiraki, was selectively eliminated by forced-feeding on low-molecular weight cellulose (LC) with a mean DP of 17. Although one week&apos;s feeding on LC caused perfect disappearance of Pseudotrichonympha grassii Koidzumi, the selective defaunation method itself had no detrimental effect on the health conditions of termite on the basis of survival rates and weight changes of workers in the latter feeding. In addition, the fact that the defaunated workers repidly recovered their wood-attacking activity by being mixed with normally faunated workers could well support this assumption. By the results of changes of protozoan fauna when selectively defaunated workers were forced to feed on various cellulose substrates, it was suggested that each protozoan species had its inherent role in cellulose metabolism.
T Yoshimura, K Tsunoda, M Takahashi


Immunogold localisation of catalytic domain of endocellulase in the cellulosic substrates
1997 - IRG/WP 97-10205
The reaction of catalytic domain of endocellulase on the cellulosic substrates was visualised by using immunogold labelling procedures to obtain a better understanding of the mechanism of enzymatic cellulose hydrolysis. Polyclonal antibody was produced against the catalytic domain of endo-l, 4-ß-glucanase (EGI) from a ruminal anaerobic bacterium Ruminococcus albus F-40. Immuno-TEM works showed the positive labelling of polyclonal antibody of catalytic domain endocellulase on the cellulosic structures. Gold particles occurred mostly in the disrupted terminal areas of cellulose microfibrils. In contrast, gold labelling on the central part of microfibril was not so much distributed as that in the terminal part. The catalytic domain of endocellulase was presented mainly in the outer membrane of bacterial cells, suggesting that this enzyme is a cell surface protein serving to degrade the cellulosic substrates. The labelling density between the whole endocellulase and the catalytic domain of endocellulase was different. Micromorphological characteristics of cellulose degradation by this bacterium were also examined by SEM and TEM.
Yoon Soo Kim, Seung-Gon Wi, Kyu Ho Myung, K Ohmiya, S Karita


The hydrolysis of organo-boron compounds in treated particleborard
2000 - IRG/WP 00-40180
Standard particleboard (manufactured for interior applications) was treated with trimethylborate and modified trimethylborate and then left to hydrolyse for specified periods. The percentage residual trimethylborate was determined by placing samples in kerosene and analysing the kerosene for boron after 3 days of leaching. There was a significant correlation between the percentage hydrolysis of trimethylborate and the original trimethylborate concentration in the wood. The specific gravity of modified trimethylborate formulations also influenced the apparent rate of hydrolysis.
K M Filcock, P Vinden


Ultrastructure of degraded, CCA-treated Pinus radiata wood from a marine pile
1990 - IRG/WP 1461
During an inspection of marine piles, 12 years after installation, severe degradation was noted on one of them in the vicinity of a corroded eye-bolt. The wood was dark brown in colour and tended to crumble easily. Wood fragments were examined by light microscopy and scanning and transmission electron microscopy and were also analysed for carbohydrates and lignin. Light microscopy showed numerous cracks in tracheid walls resulting in delamination at middle lamella - S1 and S1 - S2 junctures and also in fractures across the tracheid wall. Chemical analysis showed extensive losses in hemicelluloses and also losses in cellulose. Observations with polarised light microscopy supported the data from chemical analysis on cellulose degradation. Although presence of microbial flora in the lumen of wood cells was revealed by scanning electron microscopy, transmission electron microscopy showed only occasional soft rot decay zones in the S2 layer. We suggest that the degradation of Pinus radiata wood cell wall is primarily due to chemical attack, fungal decay playing a minor role.
A P Singh, M E Hedley


Identification of terminal structures in cellulose degraded by the brown-rot fungus Postia placenta
1989 - IRG/WP 1389
To gain insight into the biochemical mechanism employed by brown-rot fungi to depolymerize cellulose, we identified the end-groups of chemically pure cellulose that had been depolymerized by the brown-rot fungus, Postia placenta. The depolymerized cellulose was acid hydrolyzed and the anion fractions isolated by ion chromatography. Sugar acids were identified by gas chromatographic and mass spectrocopic analysis. Cellulose degraded by Fenton&apos;s reagent (H2O2/Fe2+) was also analyzed. The two systems generated the same sugar acids but not in the same quantities. The acids identified include glyceric and erythronic, indicating oxidative cleavage of the vicinal diol carbon-carbon bonds within glucosyl residues in the cellulose polymer. Gluconic and arabonic acids were also identified as major products. No uronic acids were produced in either systems.
T K Kirk, T L Highley, R E Ibach, M D Mozuch


An electron spin resonance study of manganese changes in wood decayed by the brown-rot fungus, Postia placenta
1988 - IRG/WP 1359
Electron spin resonance (ESR) spectrometry was used to examine wood decay by the brown-rot fungus, Postia placenta. Wood slivers of Douglas-fir, white fir, redwood, sweetgum and yellow poplar were incubated for 4 weeks in custom-made quartz ESR tubes with or without Postia placenta. In all wood species without fungus, a weak partially resolved signal (about g=2, presumably due to manganese) was detected. No manganese-like signal was found in aerial hyphae of the fungus. Wood slivers with fungus had a smooth, well-resolved manganese signal with a larger amplitude than wood without fungus, indicating a larger amount of paramagnetic manganese. The ratio of amplitudes for slivers with and without fungus increased with incubation time, reflecting an accumulation of paramagnetic manganese during decay. Due to the nature of this closed system without culture media, the accumulation of paramagnetic manganese is most likely due to the change of wood manganese by the fungus.
B Illman, D C Meinholtz, T L Highley


Natural weathering of wood in a sunny climate effects on surface chemistry and paint adhesion
1997 - IRG/WP 97-20109
Radiata pine veneers and blocks were exposed to natural weathering under Australian summer conditions over a period of 30 days. Infrared spectroscopy revealed that there was perceptible surface delignification after 4 hours exposure, substantial surface delignification after 3 days exposure and almost complete surface delignification after 6 days. Viscometry determinations on holocellulose samples from weathered veneers and unweathered controls indicated significant depolymerisation of cellulose after short periods of weathering. A tape test was used to assess the adhesion of acrylic latex primers to weathered blocks. The adhesion of exterior acrylic primers decreased on weathered wood surfaces and was significantly lower on specimens that were weathered for 5 to 10 days. An oil-modified acrylic primer showed greater adhesion to weathered wood surfaces. Primer adhesion was lower on weathered radial surfaces than on similarly exposed tangential surfaces. The practical implications of these findings for the coating of exterior wood with acrylic latex primers and the development of photoprotective treatments for wood are discussed briefly.
P D Evans, P D Thay, K J Schmalzl


Effect of angle of exposure on degradation of radiata pine during weathering trials
1988 - IRG/WP 2301
The importance of angle of exposure on the degree of weathering of materials has not been adequately resolved. In conventional tests, specimens are exposed at an angle of 45° facing the equator, but more recently experiments on polymeric materials have suggested that an angle of 0° may be preferable since this angle maximises levels of received ultra-violet radiation. In this paper the degradation of Radiata pine (Pinus radiata D. Don) during weathering was assessed at 5 angles of exposure (0°, 45°, 60°, 70°, 90°) over 50 days by measuring changes in weight and chemical composition. In order to confirm previous observations measurements of received ultra-violet radiation (< 320 nm) at these angles of exposure were also made using polysulphone polymer film dosimeters. Roth weight loss and chemical data indicate that degradation of Radiata pine during weathering was negatively correlated (p < 0.001) with increasing angle of exposure. The implications of these findings for the conduct of weathering trials are discussed.
P D Evans


Soft rot decay in acetylated wood. Chemical and anatomical changes in decayed wood
2002 - IRG/WP 02-40231
Acetylated Beech (Fagus sylvatica) and Scots Pine (Pinus sylvestris) wood were studied in soil beds under laboratory conditions for longer periods. High mass losses and dynamic MOE losses were measured in non-acetylated wood and at lower weight percent gains (WPG). Rapid losses of lignin, holocellulose and ?-cellulose occurred in non-acetylated beech wood and no losses were detected at the highest WPG. Changes in chemical composition of acetylated beech wood at lower WPGs was measured. Slight changes in chemical composition of non-acetylated Scots pine wood were also observed and minor changes in acetylated wood at all WPGs; except in holocellulose. An intensive anatomical study was performed by light microscopy and SEM microscopy. The results are presented and discussed. Results showed a significant prevention of acetylation against fungal growth above 8 % and 10 % WPGs in beech and pine respectively.
B Mohebby, H Militz


Preservative effect of cellulose insulation material against some mould fungi and brown rot fungus Coniophora puteana in pine sapwood
1991 - IRG/WP 1484
The influence of mineral wool and loose-fill cellulose wool on biodeterioration of pine sapwood was studied. The test fungi were mould fungi Aspergillus versicolor, Cladosporium sphaerospermum, Penicillium sp. and Aureobasidium pullullans and brown rot fungus Coniophora puteana. Cellulose wool inhibited the growth of mould fungi on the face of wood contacted with insulation material at RH of 97 and 100%. During 6 months&apos; incubation boron compounds added in cellulose wool diffused into the wood. No growth of brown rot fungus was detected in "treated wood". Mineral wool had no preventive effect on the growth of mould fungi and brown rot fungus Coniophora puteana.
H Viitanen


Effects of alkali treatment on some mechanical and chemical properties of creosote treated oaks
1991 - IRG/WP 2366
To date, there is a lack of information on the effects of chemical treatment on the performance of creosote preservative treated oak sleepers. This factorial experiment was designed to analyze three main effects: species (Quercus alba and Quercus rubra) creosote treatment (treated and untreated), and alkali (NaOH) soaking (0, 1, and 10 percent). The modulus of elasticity (MOE) and fiber stress at proportional limit in compression perpendicular to grain, hardness modulus, surface hardness, alcohol-benzene extractives, hot-water extractives, 1% NaOH extractives, lignin, pentosans, holocellulose, and alpha-cellulose content were determined on specimens. The test results indicated that species, creosote treatment, and alkali soaking significantly affect both the mechanical and chemical properties of the oak sleepers.
P Chow, A J Reinschmidt, E J Barenberg, L C Chang


Biochemical relationships between biodegradation of cellulose and formation of oxalic acid in brown-rot wood decay
1991 - IRG/WP 1472
Non-enzymic hydrolysis of cellulose with low concentrations of oxalic acid was examined. The incubation of pine wood pulp with 1% oxalic acid (pH 1.3) at 35°C for 4 weeks reduced the original viscosity to 60%. Reducing sugars were liberated from various cellulosic samples by the oxalic acid treatment. However, crystallinities of cellulose in those samples did not change before and after the treatments. Then, the enzymatic formation of oxalic acid was investigated in relation to cellulose biodegradation by brown-rot fungi. We succeeded in isolating oxaloacetase from the brown-rot fungus Tyromyces palustris in cell-free extracts which catalyze hydrolysis of oxaloacetate to produce oxalate and acetate. During the brown-rot wood decay process, oxaloacetase may play an important role in degradation of wood carbohydrate.
M Shimada, Y Akamatsu, A Ohta, M Takahashi


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