Your search resulted in 120 documents. Displaying 25 entries per page.
Localization of oxalate decarboxylase in the brown-rot fungus Postia placenta
1996 - IRG/WP 96-10161
Oxalate decarboxylase, the enzyme that breaks oxalic acid down into formic acid and carbon dioxide, was recently detected in mycelial extracts of the brown-rot fungus Postia placenta. Differential centrifugation was used to demonstrate that the enzyme is loosely associated with the hyphal surface. Enzyme activity can be removed by washing the hyphae with a low pH buffer. Only low levels of activity were detected in soluble and membrane-bound intracellular fractions. The presence of the enzyme on the hyphal surface and possibly in the hyphal sheath supports the hypothesis that this brown-rot fungus actively regulates the pH and oxalic acid concentration of its environment.
J A Micales
Physiologic response of Phanerochaete chrysosporium to exposure to triazole fungicides
1994 - IRG/WP 94-10066
Triazoles are increasingly important fungicides which are employed for a variety of applications included wood protection. Several recent studies suggest that white rot fungi are more tolerant of triazole compounds than other wood degrading fungi. Cultural studies using a white rot fungus, Phanerochaete chrysosporium, and 0.2 or 0.8 ppm of tebuconazole or propiconazole suggested that mycelial dry weight was most affected by the presence of triazoles. Extracellular carboxymethylcellulase, cellobiosidase and phenol oxidase activities were depressed but not inhibited by triazoles, while ß-glucosidase activity appeared to be slimulated by the presence of these biocides. The results suggest that white rot fungi may be less sensitive to triazoles and this diminished sensitivity may permit these fungi to become more important on wood treated with this biocide.
J J Morrell, R K Velicheti
Effects of Trichoderma harzianum on enzyme activity and oxalic acid production of Gloeophyllum trabeum in ponderosa pine sapwood blocks
1992 - IRG/WP 92-1550
The effect of a bioprotectant, Trichoderma harzianum, on the activity of Gloeophyllum trabeum was investigated using a wood wafer sandwich method. Wood weight loss was greatest with Gloeophyllum trabeum exposed wafers, intermediate with those exposed to both the bioprotectant and decay fungus, and lowest with the bioprotectant exposed wafers. Extracts of wood wafers after 2, 4, or 6 weeks of fungal exposure revealed that the bioprotectant depressed, but did not completely inhibit enzyme activity of the decay fungus. Analysis of extracts for oxalate content revealed that the bioprotectant had little effect on the levels of oxalate present. The results suggest that the bioprotectant was not capable of completely inhibiting the decay fungus. Further trials to evaluate the effect of prior bioprotectant colonization on basidiomycete activity are planned.
C M Sexton, J J Morrell
Enzyme systems of bacterial isolates from ponded logs - Potentials of pectin and/or starch degradation
2000 - IRG/WP 00-10378
This paper deals with the degradation potentials of wood constituents by the bacterial isolates from ponded logs. The potentials to degrade pectin as a constituent of pit-tori as well as starch existing in ray parenchyma cells in the areas of sap- and transition wood with the isolates were examined. The pectinase activity was investigated by means of the degradation degree of a carrot strip used as a single carbon source in a liquid medium. The amylase activity was studied by the colour change on the iodostarch reaction in an agar medium containing soluble starch as a single carbon source. The results suggested that these substrates were degraded sequentially by plural bacterial species that invaded in the logs during ponding.
S Doi, S Ohta
Redox regulation of enzyme activity during wood decay
1996 - IRG/WP 96-10172
A potential strategy in the search for alternative wood preservatives against fungal decay is to target the extracellular wood-decay process itself, rather than the decay organisms. This presents novel targets for selective disruption and possibly without the broad-spectrum toxicity associated with conventional wood preservatives. The enzymes of white rot decay are mechanistically diverse (e.g. hydrolytic, oxidative, peroxidative) and therefore various strategies for the disruption of their activity can be conceptualized. We have characterized how effectors control activity of the extracellular enzyme glyoxal oxidase. This enzyme is secreted by Phanerochaete chrysosporium and produces hydrogen peroxide required by ligninolytic peroxidases. Our studies with recombinant glyoxal oxidase show that the native enzyme is activated by inorganic oxidants or by lignin peroxidase when peroxidase substrates of high redox potential are used. The interconversion between active and inactive forms of the enzyme is defined in redox terms based on spectroelectrochemical measurements of the active site of glyoxal oxidase.
P J Kersten, B Kurek, J W Whittaker
Effect of Pseudomonas cepacia on the activity of a mixture of wood staining fungi on ponderosa pine sapwood
1995 - IRG/WP 95-10107
There are major incentives for limiting the degree of fungal discoloration which occurs during wood processing. Most lumber producers apply prophylactic fungicides which limit microbial growth, but increasing restrictions on the use of these chemicals have encouraged the search for alternative stain prevention strategies. Among the possible strategies for stain prevention is biological control. While biological control or protection has worked well in the laboratory, it often fails in the field probably because conditions are unsuitable for growth of the bioprotectant. These failures highlight the need for developing a better understanding of the nature of biological protection. In an effort to develop this information, the effects of Pseudomonas cepacia on the physiologic responses of a consortium of wood staining fungi was investigated on ponderosa pine sapwood wafers. The presence of Pseudomonas cepacia markedly reduced the degree of stain, total protein, protease levels, and the activity of various wood degrading enzymes. The results suggest that the bacterium has a major impact on growth and physiology of the various stain fungi. Further studies are planned to more fully understand the nature of the bacterial impacts on fungal attack.
J J Morrell, R K Velicheti
In situ testing the influence of melamine resins on the enzymatic activity of basidiomycetes
1999 - IRG/WP 99-30194
Waterbased methanol etherificated melamine formaldehyde resins have the potential to increase the resistance of impregnated wood against wood destroying fungi. The mechanism of the increased wood durability is not clear yet. In the present paper the possible interference of melamine resins with wood degrading enzymes of Coniophora puteana and Trametes versicolor was investigated as a possible contribution to the increased wood durability. An in situ photometric assay was used to measure the enzymatic activity against Walseth cellulose, pine sapwood as well as lignin and xylan preparations.
D Lukowsky, F Büschelberger, O Schmidt
Extracellular carbohydrate production by isolates of Postia (=Poria) placenta
1989 - IRG/WP 1388
A monokaryotic strain of Postia (=Poria) placenta, ME20, which is unable to degrade wood, also failed to produce extracellular polysaccharide when grown in liquid culture, regardless of carbon source or concentration. Other isolates of Postia placenta, including another monokaryon and a hybrid of this monokaryon with ME20, produced large quantities of this material. The polysaccharide consisted primarily of glucose upon acid hydrolysis and resembled the glucan reported in culture filtrates of other wood decay fungi. It was produced primarily during the logarithmic phase of growth. Isolate ME20 formed high levels of laminarinase and glucan-degrading enzymes compared to the other isolates; the glucan of ME20 may be prematurely degraded. This study supports the importance of the extracellular matrix in the wood-decay process.
J A Micales, A L Richter, T L Highley
Chitin synthetase activity in cellular fractions of wood-decay fungi
1992 - IRG/WP 92-1524
This study was an attempt to explain the variability of in vivo sensitivity of wood decay fungi to the chitin synthetase (CS) inhibitor, polyoxin, by comparing CS distribution in cellular fractions. The five species studied were the brown-rot fungi Coniophora puteana, Gloeophyllum trabeum, Fibuloporia vaillantii, and the white-rot fungi Schizophyllum commune and Ganoderma applanatum. The CS activity was measured in crude homogenates of disrupted mycelia and centrifugation fractions consisting of 10,000 x g precipitate (cell wall fraction), 45,000 x g precipitate (mixed membrane fraction), and 45,000 x g supernatant (cytosol). Enzyme activity was different in all fractions of the same species and in the same fractions of the different species. There was great variation in CS activity of cellular fractions of the five species. The highest activity was in the cell wall and mixed membrane fractions of Schizophyllum commune, the species previously shown to have the highest in vivo polyoxin sensitivity. Trypsin increased the CS activity in cytosol of Ganoderma applanatum, but not in digitonin-treated cell wall or membrane fractions. Variability of fungal response to polyoxin D appears to be related to cellular location and activity of CS.
B R Johnson, S C Croan, B Illman
Structural changes, basidiomycete richness, enzyme activity and proteomic profiling of decay resistant and non-resistant woods over 18 months in soil contact
2010 - IRG/WP 10-10733
Wood decay fungi damage wood by production of enzymes that attack the structural components. The objective of this study was to better understand which suite of decay genes and proteins are expressed during biodeterioration of three different wood types in forest soil over time. Variation in decay genes and proteins were determined for pine (non-resistant), cedar (naturally durable), and ACQ-treated pine (chemically resistant) in a soil decay bed. Decay was assessed by visual decay ratings, dynamic MOE, and microscopy. There were no significant difference in decay between cedar and ACQ-treated pine over the 18 month period. However, there were significant differences in decay between pine and cedar and between pine and ACQ-treated pine. The fungal mycelia penetrated the cell walls of pine and were continually observed over 18 months, but not in cedar or ACQ-treated pine. Basidiomycetes containing decay genes were detected on pine which also had a greater diversity of fungi compared to cedar and ACQ-treated pine. No basidiomycete genes were expressed and only a few basidiomycetes were identified on cedar which also showed little decay. ACQ-treated pine also showed a little decay however basidiomycetes were present and active. Proteins were first detected on pine and ACQ-treated pine at 6 months and the numbers continued to increase through 18 months, but were not detected on cedar until 14 months. There was greater number of total proteins on pine than cedar and ACQ-treated pine at each time period. From these results, the natural durability of cedar reduced the wood decay community and its activities. It appears that ACQ-treated wood did not stop the growth of the decay fungi and the production of the decay enzymes but the chemical treatment did inhibit the effectiveness of the enzymes thus decay.
Youngmin Kang, S Diehl, L Prewitt, D Nicholas
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
Role of microbiota in wood degradation by Reticulitermes grassei and Bursaphelenchus xylophilus
2022 - IRG/WP 22-20684
Xylophagous organisms can cause damage both in forests and in felled wood. Bursaphelenchus xylophilus, which causes "Sudden Pine Wilting" in coniferous forest masses, and is currently considered a quarantine organism in the European Union. On the other hand, structural and carpentry wood is affected by subterranean termites (Reticulitermes spp.), that cause serious damage, both in buildings and furniture. Solutions for the control of both organisms have been evaluated, and mainly based on chemical or physical treatments. Lately more eco-sustainable biocontrol and/or bioprotection techniques are being investigated. Among these techniques, the modification of the associated microbiota is being studied, in nematode or entomopathogenic microorganisms, with metabolites that are capable of controlling both organisms. As these products are of biological origin they may minimize the environmental impact. The application of these latest techniques requires a deep understanding of the associated microbiota. Therefore, the objective of this work has been to identify the microbiota present in Bursaphelenchus xylophilus and Reticulitermes grassei, as well as their main enzymatic activities and how they may play important roles in the degradation of wood. The results have shown cellulase, chitinase and protease activities, enzymes that could serve as indicative parameters in the control of both organisms. This study opens future treatment techniques against both pests, within a sustainable bioeconomy.
L Robertson, S Rames, M Uriel, J M González, F Llinares, S M Santos, M T Troya
Physical properties of ß-1,4-Xylanase produced by Postia (=Poria) placenta: Implications for the control of brown rot
1987 - IRG/WP 1318
The degradation of hemicelluloses is an early event in wood decay by brown-rot fungi. An understanding of the physical properties of hemicellulases may suggest target mechanisms for the development of new control agents. Endo-b-1,4-xylanase was partially purified by column chromatography from wood decayed by Postia (= Poria) placenta. The enzyme was extremely resistant to denaturing conditions; no loss of activity was detected after 2 h in 9 M urea or 6 M guanidine-HCl. Boiling the enzyme for 5 min in 2.5% SDS + 0.5% b-mercaptoethanol reduced its activity by 65%, as measured by the production of reducing sugars. The activity of a-D-galactosidase, another enzyme detected in large quantities in the decayed wood, was reduced by 98% under these conditions. Optimum pH and temperature ranges were pH 2-6 and 50-60°C, respectively. The enzyme appears to be a glycoprotein containing 50-60% carbohydrate (w/w); the carbohydrate moiety may protect the enzyme from adverse environmental conditions. The control of brown rot by in situ inactivation of xylanase may not be feasible because of the enzyme's extreme stability.
J A Micales, F Green III, C A Clausen, T L Highley
Fungicidal activity of some organic solvents, copper carboxylates and their complexes with 2-aminoethanol
1997 - IRG/WP 97-30136
We evaluated the activity of eight organic solvents against wood - rotting fungus Trametes versicolor in order to choose the most appropriate one for rapid screening tests of some copper(II) carboxylates and their adducts with 2-aminoethanol. Their activity against the selected fungus was classified in the following order: chloroform > N,N-dimethylformamide > acetonitrile > methanol > dimethyl sulfoxide > ethanol > acetone. The non-polar white spirit did not dissolve in the growth medium and the results could not be directly compared with the results for other solvents. As an appropriate solvent for screening of the tested copper(II) carboxylates, dimethyl sulfoxide (DMSO) was chosen. Minimal inhibitory concentration against Trametes versicolor of the screened carboxylates was in the concentration range of 1x10-4 to 1x10-3 mol/l. Coordinated amine ligands slightly, and not significantly, decreased fungicidal properties of the tested carboxylates.
M Petric, F Pohleven
Temperature influence on the growing velocity and cellulolytic activities of Poria placenta strains from several locations
1986 - IRG/WP 2263
The differences observed on the FPRL 280 Poria Placenta strain at several Research European Laboratories for determining up the fungicide effectiveness of wood preservative has carry us to do a comparative study about the cellulolytic activity and growth velocity of each of this strains at different temperatures (22, 24 and 28°C). The results show significative differences when the temperature is changed.
A M Navarrete, M T De Troya
Studies on the biological improvement of permeability in New Zealand grown Douglas fir
1983 - IRG/WP 3231
This report outlines progress towards optimizing conditions for water storage of New Zealand grown Douglas fir with the aim of improving permeability to water-borne preservatives, in particular CCA. Small scale laboratory tests are in progress but the need to scale up to potential commercial applications is being considered. Mixed populations of bacteria isolated from 10 week water sprinkled Douglas fir are being used to inoculate green, sterile timber. Environmental parameters such as pH, temperature and nutrient status are controlled to evaluate optimum conditions of growth, enzyme production and pitmembrane degradation leading to permeability improvement.
K J Archer
Questionnaire for Volume 2 of the basidiomycete monographs
1985 - IRG/WP 1254
12 monographs of wood destroying basidiomycetes were published in volume 1. Volume 2 includes the following 17 basidiomycetes: Antrodia serialis, Chondrostereum purpureum, Climacocystic borealis, Fomitopsis pinicola, Hyphoderma tenue, Lentinus degener, Lentinus squarrulosus, Paxillus panuoides, Phellinus contiguus, Poria xantha, Pycnoporus sanguineus, Rigidoporus vitreus, Serpula himantoides, Sistotrema brinkmannii, Stereum sanguinolentum, Trametes corrugata
Lignin degradation by wood-degrading fungi
1986 - IRG/WP 1310
The wood-degrading white-rot fungus Phanerochaete chrysosporium, has been the subject of intensive research in recent years and, based upon isolation of the extracelluar enzyme ligninase, major advances have now been made toward elucidating the mechanism by which this fungus degrades lignin. From these developments, a model emerges which could explain the process by which wood-degrading fungi in general, attack lignin.
P J Harvey, H E Schoemaker, J M Palmer
Differences in feeding activity among colonies of Formosan subterranean termite Coptotermes formosanus Shiraki
1983 - IRG/WP 1202
Feeding activities of 7 colonies of the Formosan subterranean termite, Coptotermes formosanus Shiraki, were examined. Wood-consumption rates among colonies differed significantly, ranging from 23.80-78.48 mg/g/day. This large intraspecific variation raised a question of whether differences in feeding activity reported for other termite species were due to interspecific differences. When rates were expressed as mg wood consumed by one g termite per day (mg/g/day), termites of larger body weight appeared to consume less wood. This negative correlation, however, was not significant when rates were expressed as mg wood consumed by an individual per day (mg/worker/day).
N-Y Su, J P La Fage
Antifungal activity of a stilbene glucoside from the bark of Picea glehnii
2001 - IRG/WP 01-10402
Stilbene glucosides are widely distributed as phenolic extractives in the bark of Picea glehnii, a commercially species planted in the northern area of Japan, and its content reaches to more than 10% by the dried weight of the bark. Although antifungal activities of these compounds have been reported, the mechanism of growth inhibition is still unclear. Isorhapontin (5,4'-dihydroxy-3'-methoxystilbene-3-ß-D-glucoside) is the major constituent of the stilbene glucosides in the bark of P. glehnii. In the present work, the relation between metabolism and antifungal activities of isorhapontin for the white-rot fungus Phanerochaete chrysosporium and the wood staining fungus Trichoderma viride was investigated. Inhibition of fungal growth was obviously depending on the conversion of isorhapontin to the aglycone isorhapontigenin (3'-methoxy-3,5,4'-trihydroxystilbene) by ß-glucosidic activities in the cultures. Exogenous addition of ß-glucosidase also enhances the antifungal activity of isorhapontin. Moreover, less than 100 ppm addition of the stilbene aglycone isorhapontigenin is sufficient to inhibit the growth of both fungi. However, further metabolism of isorhapontigenin was observed after prolonged incubation of the fungi and resulted in detoxification.
S Shibutani, M Samejima
Fungicidal properties of boron containing preservative Borosol 9
2004 - IRG/WP 04-30348
The fungicidal properties of new boron containing wood preservative Borosol 9 is described in this paper. These properties were of particular interest as this new boron containing preservative, exhibit very good performance against wood damaging insects. But because the tested boron formulation contain also nitrogen compounds, we wanted to verify if nitrogen as a nutrient could promote growth of wood rotting and blue stain fungi. Fungicidal activity of the boron based wood preservative Borosol 9 was evaluated according to the standard EN 113 procedure. Samples made of Norway spruce were brushed two times with 10% aqueous solution of Borosol 9, air dried, steam sterilized and exposed to the following wood rotting fungi: Coniophora puteana, Gloeophyllum trabeum and Lentinus lepideus. After 16 weeks of exposure the specimens were isolated and their mass losses were determined. After this respective period, the treated wood samples lost on an average less than 1 % of their initial mass. Parallel to this experiment, blue stain testing according to the EN 152-1 procedure was performed. Specimens brushed with Borosol were for six weeks exposed to blue stain fungi Aureobasidium pullulans and Sclerophoma pithyophila. After testing period the specimens were isolated and anti blue stain efficacy was determined visually. Both tests showed that Borosol 9 has fungicidal properties. Preservative, containing the boric acid - alkanolamine complex did not enhance fungal decay or growth. On the contrary, they showed high activity against wood decay and blue stain fungi.
G Babuder, M Petric, F Cadež, M Humar, F Pohleven
The preliminary characterization of ß-1,4-xylanase of the brown-rot fungus Gloeophyllum trabeum
1990 - IRG/WP 1447
The extracellular ß-1,4-xylanase of the brown-rot fungus, Gloeophyllum trabeum, was isolated from crude extract by chromatofocusing method (PBE 94 column chromatography). The isoelectric point was estimated to 4.2-4.8 by cromatofocusing and 4.5 by isoelectric focusing (IEF). The molecular weight of the enzyme was estimated to 37,000 dalton by SDS-PAGE. The optimal temperature for the crude extract xylanase was +70°C. The enzyme stability, after 1 h incubation, decreased sharply above +60°C and pH 6.
A-C Ritschkoff, M Rättö, L Viikari
Some tests on ES - AS 11, a novel anti-sapstain formulation, and its properties
1987 - IRG/WP 3399
The results of some tests with the formulation ES - AS 11 are given. The formulation is an attempt to improve the performance of an anti-sapstain chemical by: 1) increasing its penetrability 2) uniquely combining its active ingredients. Very short times of treatment (dipping not longer than 5 seconds), low concentrations of active ingredients, and lower toxicological and environmental risks may be a promising result.
The development of a screening method for the activity of pyrethroids against wood boring marine crustaceans, Limnoria spp
1978 - IRG/WP 443
The present work is concerned with the develepment of a suitable bio-assay technique to determine the biological activity (contact action) of pyrethroids against Limnoria spp. Estimates of the toxicity of three pyrethroids, permethrin, cypermethrin and decamethrin (the structures of which are shown in Fig. 1.) to the marine borer have been obtained.
D Rutherford, R C Reay, M G Ford
Report of activity of CEN/TC 38: Test Methods for Wood Preservatives
1987 - IRG/WP 2287