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A rapid colorimetric assay for mold spore germination using XTT tetrazolium salt
2011 - IRG/WP 11-20462
A rapid colorimetric assay was developed to quantitate metabolic activity in mold spores during germination using 2,3-Bis(2-methoxy-4-nitro-5-sulfophenyl)-5-[9phenyl-amino)carbonyl]-2H-tetrazolium hydroxide (XTT). The assay was used to demonstrate inhibition of spore germination following exposure to different biocides and variability in the inhibition of spore germination of different mold species to the same biocide.
C A Clausen, V W Yang

A new model for wetting and drying of wood end-grain – with implications for durability and service-life
2011 - IRG/WP 11-20477
New experimental data for wetting and drying of wood end-grain, Sandberg (2009), imply that traditional models for moisture transport are not at all applicable. A new model is developed to consider the phenomenological behaviour of water transport in and out of end-grain, using the pore water pressure and sorption scanning properties. Modelling results are compared to experimental results and the consequences for durability are discussed.
L-O Nilsson, K Sandberg

The Effect of Soil pH on the pH of Treated Southern Pine in Ground Contact after 12 Months
2011 - IRG/WP 11-50281
Southern pine samples treated with soluble and particulate copper solutions were subjected to three soils that had been amended to provide acidic, neutral and alkaline conditions. Wood pH was measured prior to, and after 6 and 12 months after being placed in the soil to determine the effect of soil pH on wood pH.
L Jin, C Schauwecker, C Vidrine, P Walcheski, A Preston

Annual Report 2010
2011 - IRG/WP 11-60302
IRG Secretariat

Agenda 2011 Plenary meeting
2011 - IRG/WP 11-60303
IRG Secretariat

The 42nd Annual Meeting of IRG. Abstracts of documents
2011 - IRG/WP 11-60304
IRG Secretariat

The 42nd Annual Meeting of IRG. Programme
2011 - IRG/WP 11-60305
IRG Secretariat

Budget for 2011 (forecast May 2011)
2011 - IRG/WP 11-60306
IRG Secretariat

Budget for 2012
2011 - IRG/WP 11-60307
IRG Secretariat

Reporting minutes of the Plenary Meeting 2011
2011 - IRG/WP 11-60316
IRG Secretariat

IRG Documents 2011
2011 - IRG/WP 11-60318
IRG Secretariat

Section reports from IRG 42
2011 - IRG/WP 11-60317
J Lloyd

Termite Resistance of Different Wood Panels Treated with Bifex® under Laboratory and Field Trials
2011 - IRG/WP 11-10745
The effects of Biflex® on termite resistance of laminated chip Board, MDF (Medium Density Fiber), Ply Wood and Veen Board at 50 ppm were evaluated. Laboratory and field trials resistance tests showed that all woods treated with Biflex were resistant to termites as compared to untreated ones. It was concluded that as chemical loadings increased, termite mortalities increased, and at the same time the weight losses of the samples decreased. It was also found that commercially treated samples of laminated chip Board and MDF woods showed notable performance of termite resistance.
F Manzoor, S A Malik, B M Ahmed Shiday, A Liaquat, N Naz

NHA Choice test: Feeding dilemma for Reticulitermes flavipes (Kollar)
2011 - IRG/WP 11-10746
An AWPA laboratory choice test was performed with Reticulitermes flavipes (Kollar) to determine the role of feeding stimulation or aggregation by N’N napthaloylhydroxylamine (NHA). Pine blocks were vacuum treated with aqueous concentrations of NHA ranging from 250-10,000ppm and exposed to one gram R. flavipes workers in the dual block choice test which included one treated and one untreated block per modified AWPA laboratory test (E1-97) jar. At the end of four weeks, all test blocks were removed and replaced by either filter paper or untreated pine or aspen to observe long-term mortality/survival. Removed blocks were evaluated for mass loss and statisitical evaluation. Mass loss was consistently greater in the untreated-pair blocks and ranged from 18-35%. Weight loss in the NHA-treated blocks was highest at low concentrations (18%) and decreased to < 5% at 10,000ppm. Termite mortality at the end of four weeks was observed nearly zero, however, over the next 12 weeks worker mortality reached 100% in certain groups. Filter paper or control pine was supplemented after the 4 week test period. We hypothesize that exposure to untreated pine during exposure to the NHA blocks delayed the 100% mortality previously observed in similar no-choice test using similar NHA concentrations of NHA, possibly by reduction below toxic levels. Modest accelerated feeding (stimulation) of the control blocks was observed only in the 2600ppm group. Overall, NHA treatment in pine behaves like a typical repellent wood preservative: as the concentration of preservative increases, feeding and mass loss decreases, however addition of an untreated pine block abrogates the high toxicity of NHA to R. flavipes (100%) as previously seen in several no-choice tests.
F Green III, S N Kartal, P K Lebow, R A Arango

Natural durability of wood tested in different environments in Northern Europe
2011 - IRG/WP 11-10747
Moisture is often recognised as a key factor regarding the long time performance of wooden products, and one of the main challenges for timber products is to predict accurate service life in use class 3 (not covered above ground) and use class 4 (in soil or fresh water contact). A range of durability classification studies have been performed both in field and laboratory. But for several wood species information regarding the durability in use class 3 is lacking. Also, there is still a lack of studies comparing replicate wood products in different field exposure situations. This study evaluates the natural durability of different North European wood species in two different climates and in two different use classes. The wood species were compared with imported species and two preservative treatments. The overall picture shows a higher decay rating for wood species tested in ground contact compared with the results from the above ground “Double layer tests”. Moreover, the woods tested in Western Norway are more decayed than those tested in Eastern Norway. These findings can be explained by higher decay risk in use class 4 than in use class 3, and higher decay risk in a humid climate (Western Norway) than in a dry climate (Eastern Norway). The results indicate similar ranking of the durability of the wood species regardless of the environment they have been exposed to. The results from a linear regression show that MOE-loss of the mini-stakes after three years describes 70 % of the variation in decay rating of the “Double layer” stakes after six years exposure in Western Norway. This result strongly indicates that MOE-loss can be a prospective tool for rapid field testing of natural durability of wood.
P O Flæte, G Alfredsen, F G Evans

Gene expression analysis of a copper-tolerant brown rot fungus on MCQ-treated wood
2011 - IRG/WP 11-10748
Most brown rot fungi are copper-tolerant, which makes them difficult to control with copper-based wood preservatives like MCQ. To better understand what biological processes are regulated, we used our model species, Antrodia radiculosa, to examine expression of genes on MCQ-treated wood. Our hypothesis was genes that decreased copper bioavailability would be up-regulated early, when wood showed no strength loss, while genes that degraded the structural polysaccharides would be up-regulated late, when wood exhibited high strength loss. We used a global profiling strategy called RNA-Seq to record all the genes that were actively being expressed at the two time points. We found 544 differentially expressed gene models. 52 of these gene models had putative functions directly related to oxalate production and polysaccharide degradation. Increased oxalate production at the early time point was caused by up-regulated expression of the following gene models: two pyruvate decarboxylases (3x), one citrate synthase (4x), one isocitrate lyase (8x), one oxaloacetate hydrolase (4x), and four mitochondrial carrier proteins (up to 9x). Up-regulation of oxalate is consistent with the theory that fungi remove copper toxicity by forming insoluble copper oxalate crystals. With respect to the late time point, we found sixteen gene models from at least six different glycoside hydrolase families (GH5, GH10, GH12, GH3, GH61, and GH53) that were highly up-regulated (as much as 23x), along with many sugar transporter genes. Function of the glycoside hydrolases involved cleavage of the -bonds typical of the hemicelluloses and cellulose, which explained the 52% strength loss observed at the late time point. Interestingly, two different sets of gene models for pectin hydrolysis were up-regulated at both early and late time points, suggesting that the pectic substances they targeted were slightly different. These results are significant for wood protection because we have identified the genes that are regulated to uptake sugars, control oxalate levels, and to enzymatically degrade pectin, cellulose, and the hemicelluloses. By knowing these control points, we can rationally develop the next generation of environmentally safe wood preservatives. We also hope to exploit novel brown rot biochemistries for new industries, like biological pretreatment of wood for cellulosic ethanol production.
J D Tang, A Perkins, S V Diehl

Isolation and evaluation of Lactobacillus brevis from chilli waste for potential use as a wood preservative
2011 - IRG/WP 11-10749
Lactic acid bacteria were isolated from chilli waste and evaluated for their ability to arrest wood rotting basidiomycetes. In previous work a quick screening method using 96 well plates and measuring absorbance to determine fungal growth was developed specifically to investigate the efficacy of isolated bacteria against wood decay fungi. Using this method, one bacterium (isolate C11) was identified from three bacterial isolates as having significant antifungal properties against Oligoporus placenta. This isolate was identified as Lactobacillus brevis by 16S rRNA gene sequencing and BLAST analysis of the NCBI database. To determine antifungal activity in wood, Pinus radiata blocks were impregnated with L. brevis strain C11 cell free supernatant (CFS) and exposed to brown rot fungi O. placenta, Antrodia xantha, and Coniophora puteana. The CFS treated timber demonstrated resistance to degradation from all fungi especially when L. brevis was incubated for one week before filtering the culture to retrieve the supernatant. To determine the nature of the bacterial metabolites affecting fungal growth, the affect of pH, temperature and proteinaceous enzymes on the CFS was assessed using the 96 well quick screening method. The antifungal metabolites were heat stable and not affected by proteinase K, but were affected by neutralisation with NaOH suggesting the metabolites were of an acidic nature.
D O’Callahan, T Singh, I R McDonald

Basidiomycete colonization of Scots pine sapwood quantified by qPCR and TGA
2011 - IRG/WP 11-10750
Scots pine (Pinus sylvestris L.) is an important softwood species in Northern Europe and is frequently used as material for various wood protection systems. In Europe, EN 113 is the standard basidiomycete laboratory durability test method, using mass loss as evaluation criteria. In this paper quantitative real-time PCR (qPCR) and thermogravimetric analysis (TGA) was used to characterize colonization by basidiomycetes in Scots pine sapwood, but also to learn more about the EN 113 test. Two different wood sample sizes were tested. For Gloeophyllum trabeum the largest sample size gave the highest mass loss, while for the smallest samples Trametes versicolor gave the highest mass loss. As expected, fungal DNA content and mass loss in Scots pine sapwood samples decayed by G. trabeum became higher with increasing incubation time of 16 weeks. More unexpectedly, the T. versicolor DNA content in Scots pine sapwood samples was highest at the start of the incubation period and declined during the incubation period, while mass loss increased during the 28 week incubation period. The fungal colonization in the side and middle of EN 113 samples was tested. Highest DNA contents of G. trabeum were measured in the sides during 16 weeks of incubation. The T. versicolor DNA content was higher or similar in the side compared to the middle of the samples until week 20. For weeks 20 and 22 the DNA content was higher in the middle than in the sides, while for the remaining incubation period (weeks 24, 26 and 28) it was quite similar. TGA was shown to be a useful and fast method for chemical characterization of brown rot decayed wood, but cannot be used for white rot decayed wood. For T. versicolor moisture and fungal DNA explained most of the variation in mass loss, while for G. trabeum moisture explained most of the variation in mass loss.
G Alfredsen, S Bollmus, T K Bader, K Hofstetter

The effects of acetylation level on the growth of Postia placenta
2011 - IRG/WP 11-10751
To understand the defence mechanisms utilized by decay fungi when exposed to different wood protection systems the study of gene expression can give us some answers. When the DNA sequences are known, primers can be designed to detect transcripts of genes with gene products related to basic cellular processes and hyphal growth. The characteristic gene products induced in different fungi by different wood protection systems can be identified. Studies on the expression of fungal genes will give us a better understanding of the fungal degradation of wood and we can optimize wood protection systems. Hence, no single technique will give us the answer to all questions about the decay of wood we need to gather small pieces of the puzzle using different approaches. The aim of the present study was to investigate the effects of acetylation level on the growth of Postia placenta with regard to amount of total DNA and gene expression targeting 7 different genes. This paper presents preliminary results after 4 weeks of incubation. The results presented in this paper are parts of a larger project which reaches over a period of 36 weeks with sampling times after 12, 20, 28 and 36 weeks. We found no mass loss in the acetylated samples after 4 weeks of incubation in a modified soil-block test. The presence of P. placenta DNA and the absence of mass loss could indicate on an inability of the mycelia to establish a wood exploitation phase. Two genes related to carbohydrate metabolism were expressed in a higher amount in P. placenta during growth on untreated wood than during growth on acetylated wood. However, for a third gene, also related to carbohydrate metabolism, the relationship was the opposite. Two genes related to oxidative metabolism were expressed in a higher amount in P. placenta during growth on acetylated wood than during growth on untreated wood and another two genes related to oxidative metabolism showed inconsistent results.
A Pilgård, G Alfredsen, C G Fossdal, C J Long II

Decay resistance attributes of teak (Tectona grandis L. f.) wood: comparison of the fungicidal activities of quinones
2011 - IRG/WP 11-10752
The implication of quinones in decay resistance of teak wood is controversial. To better understand the role of individual quinone in this property, we studied the correlations between this latter and the content of 2-(hydroxymethyl)anthraquinone, tectoquinone, anthraquinone-2-carboxylic acid, 1,4-naphthoquinone, lapachol and the new compound 4’,5’-dihydroxy-epiisocatalponol found in teak wood. Then, we studied the fungicidal activities of these quinones in comparison to acetone/water extracts from teak heartwood and sapwood and also with the commercial biocide tebuconazole. Broth dilution technique was used to assess the toxicity of these compounds against Trametes versicolor and Poria placenta. Decay resistance was measured according to current standards and individual quinones content were quantified by high performance liquid chromatography. High positive correlations were found between teak decay resistance and the content of 4’,5’-dihydroxy-epiisocatalponol, tectoquinone, 2-(hydroxymethyl)anthraquinone. Whereas no correlation was found with anthraquinone-2-carboxylic acid, lapachol and 1,4-naphthoquinone. Concerning the fungicidal activities of teak wood extractives, acetone/water heartwood extract was toxic against the two fungi while that of acetone/water sapwood was only fungistatic. 1,4-naphthoquinone and 4’,5’-dihydroxy-epiisocatalponol from the naphthoquinones family were fungicide. However, lapachol and all studied anthraquinones (2-(hydroxymethyl)anthraquinone, anthraquinone-2-carboxylic acid and tectoquinone) were fungistatic or not toxic. In the present study, 1,4-naphthoquinone was found the more toxic with a fungicidal activity 1000-times lower than that of the commercial biocide and over 2000-times lower than that of acetone/water heartwood extracts. These results show that decay resistance of teak wood could be mostly due to the content of naphthoquinone, particularly to that of 1,4-naphthoquinone indicating that it could be used as a potential wood preservative for lesser durable species.
F B Niamké, N Amusant, N Lemenager, G Chaix, M-F Thévenon, C Baudassé, S Kati-Coulibaly, A Amissa Adima, I Gossan Ado, C Jay-Allemand

Measuring fungal cellulolytic enzyme activity in degrading wood
2011 - IRG/WP 11-10753
An enzyme assay which measures enzyme activity directly from wood will assist in the fundamental understanding of the enzyme components of the decay mechanism of rot fungi and any changes in the presence of wood protectants. At present, to measure fungal carbohydrate degrading enzyme activity in the presence of wood, two methods are used: either 1) the enzyme is measured in the growth media containing lignocellulosic material after the fungus has been allowed to utilize the cellulolytic substrate or 2) the fungus is grown on the lignocellulosic material and the enzymes are extracted using buffers after the growth period and the buffer is analyzed for enzyme activity. This research presents an enzyme assay where wood slivers are added to the assay mixture. The brown rot fungus Postia placenta was grown on wafers measuring 70mm by 23mm by 1.5mm for 12 days. The wafers were then sliced into 3mm by 1mm slivers and assayed using a micro assay using Azo-carbohydrates as substrates. The use of a 96-well microtiter plate allowed a large number of samples to be analyzed at one time with reduced reagent use. Using this assay method allows screening for enzyme activity along the length of the wafer. Our results showed detectable differences over the length of the wafer with a peak of endoglucanase activity closest to the colonization point of P.placenta. Small samples of decayed wood from the field were assayed for endoglucanase activity and the results indicate that this method has a potentially to be used to determine early decay. This assay will be useful in many research fields to gauge the presence and location of fungi and their carbohydrate degrading enzyme activity within a wood sample.
S M Duncan, J S Schilling

Quantification of four dark colored mould fungi by real time PCR
2011 - IRG/WP 11-10754
Coated wooden claddings in building facades are widely used in the Scandinavian countries, and are often preferred to other materials. Wood is facing increasing competition from other materials that are less labor intensive at the construction site and materials with less demand for maintenance thru service life, and makes further development of wooden claddings essential. Growth of discoloring moulds on exposed coated wooden claddings is mainly of aesthetic concern, and is especially disfiguring for light-colored surfaces. Growth of surface fungi often initiates repeated cleaning and shorter maintenance intervals, which in turn increase the total cost of ownership for wooden claddings. Cost and effort of ownership are often important factors considered when choosing a product, and the traditionally good market situation for wooden claddings is therefore threatened. The development of real-time PCR (polymerase chain reaction) and taxon-specific primers has provided new possibilities for specific detection and quantification of fungi in their natural substrates. In qPCR (quantitative real-time PCR), the accumulation of the PCR product is detected for each amplification cycle. An efficient and reproducible sampling and extraction of DNA is required for a high-throughput qPCR based quantification of discoloring fungi. The authors have now adjusted DNA isolation protocols and optimized real-time PCR assays for species specific detection of fungi frequently found on painted surfaces (Aureobasidium pullulans, Alternaria alternata, Cladosporium cladosporides, Ulocladium atrum).
E Larnøy, L Ross Gobakken, A M Hietala

Wood protectors sensitivity of Fusarium circinatum, a quarantine organism in Europe
2011 - IRG/WP 11-10755
In the last decade, two new organisms with a high potential damage in Conifer forests have been detected in Europe. They are the nematode Bursaphelenchus xylophilus and the fungus Gibberella circinata (anamorf: Fusarium circinatum), and have driven the European Union to protect the stands from propagation and dispersion of these new pathogens. The nematode was detected first in Setubal (Portugal) in 1999 and eradication measures were taken there. However, they were unsuccessful decreasing the infection level, so new regulations were announced (2006/133/CE, Comission on 13 february 2006). Even then, dispersion was not prevented, and Bursaphelenchus xylophilus has been detected with wood material through commercial trade. B. xylophilus is a quarantine organism and so it is Fusarium circinatum. This fungus was found in Spain in 2004 and it is a potential destructive pathogen, especially in nurseries and plantations. By other hand, timber is a material with a free market in Europe, and although it is treated with specific products against wood decay organisms, the industrial sector is worried about if the adopting measures treating the wood by thermal treatment following NIMF 15, is enough and if the wood preservatives are effective against these organisms. That’s why in Spain several organizations are developing projects to evaluate the effectiveness of the fungicide and insecticide wood preservatives used actually for the temporary and permanently protection of timber, in order to see if this kind of products has a biocide effect against these quarantine organisms. Particularly, the objective of this work has been to assess the efficacy of the wood preservatives against Fusarium circinatum, whereas is being studying the same against Bursaphelenchus xylophilus, whose results will be present in the next future.
Y Serrano, S Cobacho, A Navas, M Conde, R Raposo, M T Troya

Molecular investigation of Postia placenta growing in modified wood
2011 - IRG/WP 11-10756
Brown rot is the most common and destructive type of fungal decay for wood in service. These fungi depolymerize preferentially the structural carbohydrates, cellulose and hemicellulose in the cell wall leaving oxidized lignin behind. Modified wood can provide protection against a variety of wood deteriorating organisms, including decay fungi. However, there is still little known about the mode of function of the different wood modifications concerning the decay resistance. The biochemical mechanisms and gene products induced in brown rot during growth in modified wood are poorly understood. In this paper the data collected from mass loss studies and qPCR and qRT-PCR were used for profiling growth dynamics and gene expression of the brown rot fungus Postia placenta in different wood substrates through different stages of decay. Pinus sylvestris (L.) sapwood was used for the following treatments and modifications: chromated copper arsenate CCA (0.67%), furfurylation (WPG 37), thermal modification (D212) and acetylation (WPG 23). Untreated Pinus sylvestris (L.) sapwood was used as control. Samples were taken at different time intervals from 2 to 26 weeks. The highest mass loss and the highest fungal DNA content were found in the control samples while acetylated wood had the lowest mass loss and fungal DNA content. These results reflect a close relation of mass loss and fungal DNA content, both reflecting the amount of Postia placenta decaying the samples. Generally, expression of the investigated genes was highest in CCA treated wood. In the beginning of the incubation of all treated wood samples, the genes coding for oxidative metabolic activity had higher expression levels than the untreated control. In the end of the incubation most of these genes were less expressed than in the untreated control. The genes used for carbohydrate metabolism and the alcohol oxidase showed a significant decrease after 14 weeks of incubation. At the same time an increase in gene expression of an enzyme putative involved in lignin decomposition was detected.
B Schmöllerl, G Alfredsen, C G Fossdal, M Westin, A Steitz

The decontamination of a historical xylotheque with liquid carbon dioxide
2011 - IRG/WP 11-10757
The pharmacist Johann Heinrich Linck senior (1674-1734) created the xylotheque (collection of wood species) in Leipzig, Saxony (Germany). His son, Johann Heinrich Linck junior (1734-1807), continued the valuable and unique collection, which now belongs to the Museum Waldenburg near Dresden, Germany. In the past the cupboard, including the wood specimens, was impregnated with a wood preservative containing dangerous pesticides. Consequently, the removal of these pesticides was necessary prior to the restoration.The furniture surface was cleaned with a special detoxification agent mainly made of orange terpenes, which could not be applied to the more sensitive xylotheque specimens. Liquid carbon dioxide was favored for their decontamination. A prototype of a plant at Amsonic, Switzerland, was available for decontamination. This prototype is the topic of a research project to develop a procedure to clean sensitive industrial goods with liquid carbon dioxide.Preliminary testing of the procedure was carried out on several test specimens from new and old timber with and without impregnation using “Hylotox 59”, imitating the historical specimens. The efficiency of pesticide reduction was determined by x-ray fluorescence spectrometry (XRF) and gas chromatography (GC).It was noted that most test specimens showed no marked changes in their properties and shape. Exceptions were test specimens with high resin content. The amount of pesticides could be reduced considerably on the surface of the specimens. However, leaching of pesticides over the whole cross-section of the test specimens was incomplete. Therefore, prior to the detoxification of the timber boards additional experiments need to be carried out to optimize the parameters of the process with regard to the decontamination rate.
S Zoppke, A Unger, J Mankiewicz, M Eisbein

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