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Colonization of treated and untreated decking materials by bacteria, fungi and algae quantified by qPCR
2015 - IRG/WP 15-20568
The use of durable wood species for wood decking in outdoor applications, e.g. garden terrace (use class 3) is gaining more and more interest on the part of consumers and architects. To get detailed information on the practical use of deckings, a project was started in 2010. In total 71 different decking materials (0.03 m²) were installed and evaluated over 30 months. Beside other parameters, the emphasis was to evaluate the applicability of qPCR (quantitative Polymerase Chain Reaction) technique for measuring the dynamics of increase in biomass of the organism groups responsible for biofilm formation. For this purpose 8 decking materials (durable, not durable, modified and waterbased varnish treated wood species) were investigated concerning surface growth of biofilm forming microorganisms (bacteria, fungi and algae). The surface treatment of the decking material (larch and acetylated pine) with wood preservatives improved the performance concerning the biofilm building, and made them even more resistant to growth of microorganisms than the deckings from species with high natural durability. Periodical maintenance of the decking comprising cleaning, sanding and in some cases also rebrushing of the panels showed an influence on the estimation of biomass directly due to the removal of the biofilm.
E Stoyanova, B Schmöllerl, A Steitz, N Pfabigan, R Gründlinger

Characterization of biofilm formation on wood treated with vegetable oils by color-based image interpretation method
2015 - IRG/WP 15-40697
The protection of wood in order to extend its service life is an important issue nowadays. As an alternative to traditional wood coatings biofilms can be used. It is a living protective coating for the wood surface against UV and bio-degradation that has the ability to recover from local damage, such as cracks. This paper presents preliminary results of biofilm formation from an 8-month’s field test experiment containing yellow pine (Pinus) and beech (Fagus) impregnated with an olive and linseed oil. Oil treated samples together with non-oil treated as a reference were exposed to natural outdoor conditions on the roof of Eindhoven University of Technology in the Netherlands. Biofilm formation was monitored periodically by imaging wood surface of samples with a digital camera. A method to analyze biofilm appearance on different wood types and oils was proposed. The analysis is based on quantification of the darkening of the wood surface. Current results show that olive oil and beech is the best combination for biofilm formation. The reason for that might be the difference in wood structure and the fact that olive oil cross-link slower compare to linseed oil. Further studies on the role and state of oil, substrate and weather conditions are needed.
K Filippovych, H Huinink, L van der Ven, O C G Adan

Dynamics of biofilm formation on wood impregnated with vegetable oils
2016 - IRG/WP 16-40769
Biofilms can be used as a living protective coating for wood, showing advantages compared to traditional wood-coatings regarding sustainability and self-repair. Biofilms can be formed on oil impregnated wood. Such an oil-biofilm system has the potential of protecting the wood against UV and bio degradation, creating a homogeneously black surface with self-healing properties. Results of biofilm formation from an 18 month’s field test experiment containing beech (Fagus sylvatica), yellow pine (Pinus sylvestris) and Douglas-fir (Pseudotsuga menziesii) impregnated with olive and raw linseed oil are presented in this paper. Oil treated wood samples were exposed to natural outdoor conditions on the roof of the Eindhoven University of Technology in the Netherlands. Biofilm formation was monitored by imaging the wood surface with a digital camera. Current results show that biofilm formation on olive oil and combination of beech and linseed oil was completed in a period of 1 year.
K Filippovych, H Huinink, L van der Ven, O C G Adan

Fungal and bacterial attack of CCA-treated Pinus radiata timbers from a water-cooling tower
1991 - IRG/WP 1488
Transmission electron microscopy of decaying CCA-treated Pinus radiata timbers from an industrial water cooling tower showed presence of a thick biofilm covering some areas of the wood. The biofilm contained various morphologically distinct forms of microorganisms embedded in a slime. The study provided evidence of the activity of soft rot fungi and tunnelling and erosion bacteria in wood cells. The extent of damage to wood cells due to microbial activity varied, combined fungal and bacterial attack having the most damaging impact.
A P Singh, M E Hedley, D R Page, C S Han, K Atisongkroh

Biological control with Trichoderma harzianum in relation to the formation for spores the production of soluble metabolites
1994 - IRG/WP 94-10073
The amount of spores produced by three strains of Trichoderma harzianum on the aerial mycelium of agar cultures and in shake cultures, respectively, correlated with the inhibition zones exerted against Phanerochaete chrysosporium in an agar diffusion test. The amount of soluble antifungal metabolites as well as the protein content also correlated with the inhibition zones and the amount of spores produced. The antifungal metabolites were identified to be trichorzianines. They were the only compounds with antifungal activity. It is concluded that the trichorzianines are responsible for the biocontrol effect by soluble metabolites and that they are produced during conidiogenesis.
J Bürgel, E Horvath, J Haschka, K Messner

The formation of organotin carboxylates in bis(tributyltin) oxide - treated Pinus sylvestris sapwood
1990 - IRG/WP 3618
Tributyltin compounds have been successfully used for many years as wood preservatives, although their chemical nature in timber have not been fully elucidated. This study by 119Sn and 13C NMR spectroscopy has shown that, on impregnation into Pinus sylvestris sapwood, bis(tributyltin) oxide, (Bu3Sn)2O, is rapidly converted to tributyltin carboxylates, Bu3SnOCO·R, via reaction with components of the wood resin. It is further suggested that the formation of these species is a prerequisite for the known disproportionation reaction which occurs in (Bu3Sn)2O - treated timber.
S J Blunden, R Hill

Suppression of aerial hypha formation by spent culture filtrate of a non-degradative strain of Postia placenta
1991 - IRG/WP 1498
ME20, a wild-type monokaryotic strain of the brown-rot fungus Postia placenta, does not cause significant weight losses in standard soil-wood block decay tests and fails to form aerial hyphae in liquid and agar culture. This abnormal morphological feature may be caused by the same aberrant physiology that prevents the strain from degrading wood efficiently. ME20 releases elevated levels of the autolytic enzymes laminarinase and protease into culture media. These autolytic enzymes may degrade the cell wall and hyphal sheath, thus preventing aerial hypha formation and limiting wood colonization. If abnormally high levels of autolytic enzymes suppress aerial hypha formation, any strain of Postia placenta grown in their presence should take on the appearance of ME20. MAD698, a standard floccose test strain of Postia placenta, was grown in fresh media containing increasing concentrations of filter-sterilized spent culture filtrate of ME20. Aerial hypha formation was strongly inhibited or prevented when the spent culture filtrate made up 40% or more of the medium. Spent media from MAD698 caused a similar effect but only at higher concentrations (80 and 100%). The suppression does not appear to be caused by extracellular autolytic enzymes since commercial preparations of laminarinase, chitinase, and protease did not reproduce this effect. The suppressive agent appeared in ME20 culture filtrate after only two weeks of growth. It has a molecular weight of less than 10,000 and is resistant to boiling. Additional research is needed to characterize ist nature, thus identifying a potential biorational inhibitor of wood-decay fungi.
J A Micales

Ultrastructural observations on wood-degrading erosion bacteria
1986 - IRG/WP 1283
G F Daniel, T Nilsson

Sludge formation in timber treatment with CCA preservatives. Origin and elimination
1984 - IRG/WP 3276
The exact distributions between lignin and holocellulose and retentions on wood of copper, chromium and arsenic as a function of various sets of conditions in a factorial experiment in which combinations of three temperatures of treatment, three CCA solution concentrations, four pH's of the initial CCA solution and two timber species, namely Pinus radiata and Eucalyptus grandis, are reported. Temperature and concentration appear to have an equally important effect on the preservative chemicals retentions and distribution in timber. pH, has also an effect but somewhat less marked than temperature and concentration, with the exception of the formation of sludges. Multivariable regression equations describing the amounts of Cu, Cr and As fixed on lignin and holocellulose for both pine and eucalyptus are also presented. The timber species treated also appears to have an important influence on the amounts of chemicals fixed and their distribution. Eucalyptus appears to be much less tolerant than pine to extremes of treating conditions. The influence of treating time under the most common treating conditions is also briefly discussed.
A Pizzi, W E Conradie, A Jansen

Formation of soft rot cavities in relation to concentric layers in wood fibre walls
1983 - IRG/WP 1185
A large number of timber species attacked by soft rot have been examined using light microscopy. The S2 layers in a large number of the timbers exhibited special structural features in the form of thin concentric layers. Several observations indicate that these layers may be characterised as "weak" zones by being more easily degradable than the surrounding wall layers. The chemical structure of the concentric layers is not known although some suggestions regarding their composition are given. It was observed that soft rot cavities regularly formed in the thin concentric layers. A hypothesis is put forward suggesting that T-branching occurs as a response to a chemical stimulus, possibly by sugars released by penetrating hyphae when they transverse the thin concentric layers.
T Nilsson, G F Daniel

Termite-tunnels formation on the surface of termite-resistant wood species in field sites
2001 - IRG/WP 01-10400
In this report, termite-tunnels formation by the subterranean termite, Coptotermes formosanus Shiraki on the surface of termite-resistant wood species, namely, Hinoki (Chamaecyparis abtsu), Yoshino Hinoki (Chamaecyparis abtsu), Miyazaki Hinoki (Chamaecyparis abtsu), Hiba (Chamaecyparis abtsu) and Japanese cedar (Cryptomeria japonica) was conducted in field sites. Westernhemlock (Tsuga heterophylla), Douglas- fir (Pseudotsuga taxifolia) and Ryukyu pine (Pinus luchuensis) were used as the control. 62 The termite-resistant woods species were classified either as heartwood timber (H) or sapwood timber with a heartwood center (S) and also classified based on their prefecture of origin. Otherwise, the termite- resistant wood species for the termite test were examined in using the forms on the surface of all the termite-resistant wood species by the subterranean termite, Coptotermes formosanus Shiraki. It was found that even for termite-resistant wood species treatment with preservative chemicals is required.
Y Kadekaru, K Kinjo, S Yaga

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

Diffuse cavity formation in soft rot of pine
1992 - IRG/WP 92-1541
A new type of soft rot of southern pine longitudinal tracheids is described. In this type, soft rot cavities form by diffuse degradation of the S2 cell wall layer by hyphae growing within the cell wall. Erosion is diffuse and irregular as opposed to the restricted, periodic erosion typical of type 1 soft rot cavity formation. Proboscis hyphae remain small (diameter 0.6 to 0.8 µm) and rapidly autolyze. These proboscis hyphae are not easily recognizable with light microscopy, especially at later decay stages, and require transmission electron microscopy to confirm their presence. This may be an alternative interpretation of the type 2 soft rot of softwoods described previously as being caused by lumenal hyphae through an intact S3.
S E Anagnost, J J Worrall, C J K Wang

Settlement of fouling organisms on CCA-treated Scots pine in the marine environment
1997 - IRG/WP 97-50094
As part of an EU project to investigate the effects of CCA loading on non-target marine fouling animals, exposure panels of Scots pine treated to 12, 24 and 48 kgm-3 CCA and untreated controls were submerged at seven coastal sites (Portsmouth, UK: Kristineberg, Sweden: La Tremblade (2 sites), France: Ria Formosa, Portugal: Sagres, Portugal: Athens, Greece). Inspections were made at 6 and 12 months and the fouling community on treated and untreated panels was assessed both qualitatively and quantitatively. Over the course of the field trial patterns of fouling that were common at several of the sites were recorded. It was found that with increasing CCA loading there was a significant increase in the abundance of several species of calcareous organism. This effect was less pronounced or was absent with non-calcareous animals. There were no noticeable differences in fouling patterns between two formulations of CCA. SEM studies of the surface of CCA treated timber after 7 days submergence showed a higher biofilm accumulation than on untreated timber. The significance of these early stages of biofilm build-up will be discussed in relation to later biota settlement.
C J Brown, R A Eaton

Basisiospore production by Lentinus lepideus in vitro
1987 - IRG/WP 2276
Evaluation of fungicides active against the lower fungi by spore based bioassays is very common. Possibilities of using similar assays to evaluate preservatives against brown rot and white rot fungi, especially for use in above ground constructions, are limited by the lack of methods for production of basidiospores. Tested media containing glucose 10-30 g/l and ammonium tartrate concentrations 2-20 g/l supported fairly good spore production. Media buffered with the organic buffer 2 (N-morpholino) ethane sulfonate (MES) with phosphate concentrations of 12.5-50 mM supported good spore production.
J Bjurman

Investigation of the suitability of silver fir (Abies alba Mill.) for thermal modification
2004 - IRG/WP 04-40275
In this study the suitability of silver fir (Abies alba Mill.) was examined for thermal modification. Comparative experimental investigations were performed with silver fir and Norway spruce (Picea abies Karst.) after thermal treatments. Besides properties, which characterize the quality of heat treatments, like dimensional stability and resistance against fungal attack, strength properties of the heat treated material were tested, i.e. bending strength, modulus of elasticity (MOE), impact bending strength and resistance to abrasion. Silver fir was found to be slightly more suitable for thermal modification than spruce, when treated at 180 °C, whereas thermal modification at 220°C showed a comparable suitability for both species. Advantages of silver fir were found for its impact bending strength, durability, and formation of cracks after weathering.
C Brischke, A O Rapp

Timber preservatives and corrosion
1983 - IRG/WP 3228
A survey of preservative treated timber commodities has illustrated problems that may be caused by corrosion. After treatment, timber should be compatible with commonly used fasteners. Whilst many corrosion methods have been used in the past, no standardized method is used by workers in timber preservation. The Queensland Department of Forestry is developing laboratory test methods for assessing corrosivity of timber preservatives and treated timber. These methods will be followed by in service trials.
R I Davis

Regulation of hyphal sheath formation iron-chelator production by the brown rot fungi Gloeophyllum trabeum and Postia placenta
1994 - IRG/WP 94-10074
Hyphal sheath formation and iron-chelator production by liquid cultures of the brown rot fungi Gloeophyllum trabeum and Postia placenta were monitored over time. The effects of incubation at various temperatures, pH's and concentrations of iron, manganese and nitrogen were determined. Hyphal sheath production was observed microscopically and quantified with JAVA video analysis. The hyphal sheath was found on young and rejuvenated hyphae around the growing points and along the length of hyphae but not on the necrotic hyphae. Sheath formation was first detected after 4-6 days growth and increased until day 15. Sheath production was significantly greater in fungi growing at low concentrations of metals (0-50 µM iron or manganese) than in fungigrowing under other conditions. Increasing nitrogen concentration was correlated with decreased sheath production in Gloeophyllum trabeum. Iron-chelator production, as monitored by the chrome azurol S (CAS) assay, did not occur in detectable quantities until 3 weeks after inoculation. Iron-chelator production correlated with low concentrations of metals, but was not influenced by the sources or types of nitrogen. High levels of manganese (1000 µM) and iron (200 µM) repressed both iron-chelator production and hyphal sheath formation. Temperature and pH influenced the formation of hyphal sheath and iron-chelator production by both brown rot fungi. Gloeophyllum trabeum produced more hyphal sheath in pH 3.5 at 35°C than in the other conditions tested. Postia placenta yielded more sheath in pH 4.5 at 25°C than under other conditions.No significant relationship was observed between pH and the production of iron-chelator. Hyphal sheath formation and iron-chelator production have previously been implicated in the process of wood degradation by basidiomycetes.
Y Chen, J Jellison

Formation of polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDF) during the combustion of impregnated wood
1995 - IRG/WP 95-50040-19
Wood waste and industrial wood residues often contain various preservatives. The waste management for these residuals can be recycling, deposition or combustion. Among the three possibilities, combustion seems to be the most efficient way of disposal. To obtain detailed information about emissions of organic compounds with environmental impact, especially polychlorinated dibenzo-p-dioxins (PCDD) and furans (PCDF), different impregnated wood materials were incinerated in two furnaces after mixing with non-treated wood in a ratio of 1:4. The combustion process of residues containing organic or inorganic preservatives is influenced by the elementary composition of the preservative and the thermal and oxidative reaction paths in the flame. It was found that the concentrations of PCDD and PCDF in the exhaust gas can be kept low under good combustion conditions. However, a non-regular incineration process strongly supports increased emissions of PCDD and PCDF.
T Salthammer, H Klipp, R-D Peek

Fruitbody formation and basidiosporogenesis by the white rot fungus Pycnoporus cinnabarinus
1988 - IRG/WP 1348
Conditions for fruitbody formation by the white rot fungus Pycnoporus cinnabarinus in vitro were outlined. A marked difference in substrate requirements in comparison to previously tested brown rot fungi was revealed. Agar media containing Walseth cellulose and NH4 tartrate at 1 g/l permit profound production of basidiospores particularly at 15°C but only under light treatment. Higher NH4 tartrate concentrations and glucose addition slowed down or inhibited the fruitbody formation. Axenic basidiospores, to be used in tests for inhibitors contributing to natural durability, as well as in tests for fungicides could thus be produced.
J Bjurman

The effect of storage and subculturing on in vitro fruit body formation and spore production in Gloeophyllum sepiarium and Oligoporus placentus
2001 - IRG/WP 01-20232
Spores are widely assumed to be the main mode of infection of wood in conditions conducive to decay above ground. In order to supply spores on demand as an experimental material, fruiting body and basidiospore production in vitro by Gloeophyllum sepiarium and Oligoporus placentus have been examined. The optimum medium, time to spore production, and duration of fruiting as well as fruiting body shape varied among strains of both species. Even when the same strain was used as the inoculum source, there were differences in duration of fruiting and time to spore production in different experimental sets. This suggests that the method of mycelium storage and repeated subculturing could affect fungal capacity for fruiting and basidiospore production. Among the tested methods of mycelium storage, mycelia stored on wood blocks showed the most stable response in both fruiting and spore production.
S Choi, J N R Ruddick, P I Morris

Comments on soft rot attack in timbers treated with CCA preservatives: A document for discussion
1982 - IRG/WP 1167
This paper is not based on any particular results but rather on several observations of soft-rot during many years of studies, and on a review of the existing literature. The short time available has unfortunately not permitted a detailed review of the literature. Data and knowledge of important facts are lacking for several aspects of soft-rot attack and for reactions occurring in the wood as a result of the treatment with CCA preservatives. This has made several assumptions necessary and a number of suggestions are being made which are not backed up by results. But this document may nevertheless provide a basis for discussions. Hypothesis: (1) Soft rot attack in low susceptibility wood species is prevented at CCA levels which are too low for preventing growth of soft-rot fungi. (2) High susceptibility hardwood species are only temporarily protected by high retentions of CCA. The concentrations of CCA required are so high that they will be expected to considerably effect the grawth of soft-rot fungi. (3) Formation of T-branches is induced by a chemical factor, most probably of carbohydrate nature, in the wood cell walls. (4) The number of sites where this chemical factor occurs is depending on the carbohydrate/lignin ratio. Few sites occur in high lignin timbers whereas a high number of sites can be expected in low lignin timbers. (5) CCA treatment masks or modifies the sites so that the penetrating hyphae are unable to detect them. The masking is complete in timbers with a high lignin content whereby soft-rot attack is prevented. Only partial masking occurs in hardwoods with a low content of lignin which will allow soft-rot attack to occur. But the soft-rot decay rate is such hardwoods treated to high retentions of CCA will be reduced because of the toxic effects of the preservative.
T Nilsson

The effect of kerfing on check formation in treated white spruce (Picea glauca) poles
1981 - IRG/WP 3167
62 white spruce poles, 6 m in length, were cut from full size utility poles commercially pressure treated with preservative. 21 of the poles were treated with pentachlorophenol, while of the remainder, all of which were treated with ammoniacal copper arsenate, 22 were kerfed and 19 were unkerfed. The poles were installed in the Westham Island field test site, near Vancouver, and inspected annually. After three years of exposure, deep checks have formed in the unkerfed ACA and PCP treated poles. The average depth of the "worst" check (i.e. that which penetrated the poles to the greatest depth) in the unkerfed ACA treated poles is 2.2 times that of the poles which were kerfed. No significant difference was detected in the depth of the worst check in the unkerfed poles treated with either ammoniacal copper arsenate or pentachlorophenol.
J N R Ruddick

The susceptibility to sludging of sulfate and oxide CCA
1990 - IRG/WP 3599
Radiata pine sapwood was treated separately with a sulphate CCA-C and an oxide CCA in a pilot scale pressure plant using a full cell process. CCA solutions were recovered from the final vacuum phase, placed in plastic tubes, and their susceptibility to sludging determined by examining changes in solution pH, time required for sludge to form and weight and chemical composition of sludge formed. Sulphate CCA-C solutions showed a pH rise of 0.33 above the initial solution pH of 2.01 and a sludge, largely composed of arsenic and chrome, formed after 6-8 weeks. Oxide CCA solutions in contrast showed smaller pH changes and did not form sludge. Addition of glucose or ethanol to freshly prepared sulphate CCA-C and oxide CCA solutions at 25°C resulted in sludge formation with both formulations but sludge formed earlier and in greater quantities with the sulphate CCA-C. The results indicate that the oxide CCA is more resistant to sludging than the conventional sulphate CCA and suggest that the use of the former in treatment plants could reduce sludge formation. Further methods to minimize sludge formation in treatment plants are also discussed.
B T Mutandadzi, P D Evans

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

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