Your search resulted in 13 documents.
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
Postia placenta gene expression of oxidative and carbohydrate metabolism related genes during growth in furfurylated wood
2009 - IRG/WP 09-10701
A range of studies the last decade have shown that modified wood can provide excellent protection against a range of wood deteriorating organisms, including decay fungi. However, we still lack information about why the modified wood is protected from microbial attack. Several hypotheses have been put forward e.g. inhibition of action of specific enzymes, but they still need testing. An understanding of the mechanisms utilized by decay fungi when exposed to modified wood is important for further optimisation of new modified wood products. In this study gene expression of the brown rot fungus Postia placenta has been monitored after 2, 4 and 8 weeks of colonization in furfurylated Scots pine and control samples. Preliminary results are given. The main finding was that genes related to oxidative metabolic activity was higher in furfurylated wood compared to untreated Scots pine, and that carbohydrate metabolism related expression was lower in furfurylated wood compared to untreated control.
G Alfredsen, C G Fossdal
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
The effects of acetylation level on the growth of Postia placenta over 36 weeks
2012 - IRG/WP 12-40589
Genomic sequencing gives us a tool to systematically and rapidly discover novel genes, how their products function in the cell, and explore their interactions. 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 during decay can be identified. This knowledge 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 six different genes. This paper presents preliminary results after 36 weeks of incubation. We found no mass loss in the acetylated samples treated to a high treatment level after 36 weeks of incubation in a modified monoculture 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. The results also showed that P. placenta increased the expression of AlO (involved in production of H2O2), cytochrome P450 (related to breakdown of toxic compounds), and QRD (involved in generating biodegradative hydroxyl radicals via redox cycling) along the incubation time, growing on acetylated wood treated to a high treatment level.
A Pilgård, G Alfredsen, C G Fossdal, C J Long II
Effect of Trichoderma harzianum on induction of laccase by Trametes versicolor on ponderosa pine sapwood
1996 - IRG/WP 96-10177
Trichoderma harzianum has long been studied as a possible biocontrol agent against wood degrading fungi, and has provided varying degrees of protection in several European field trials. In laboratory trials, however, this fungus appears to be less active against white rot fungi. This characteristic was studied using a wood wafer sandwich procedure which simultaneously expose ponderosa pine sapwood wafers with and without exogenous nutrients, to both the biocontrol agent and Trametes versicolor. The results indicated that the biocontrol agent limited but did not completely inhibit weight loss by the decay fungus. Extracts of fungal exposed wafers indicated that the bioprotectant appeared to stimulate laccase production by the white rot fungus. Laccase production is normally associated with secondary metabolism induced by depletion of one or more nutrients in the substrate. The biocontrol agent apparently stimulated this process, thereby potentially accelerating the decay process. The implications of these results with regard to long term biocontrol performance are discussed.
E A Canessa, J J Morrell
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'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
The effect of tunicamycin on production and secretion of extracellular carbohydrate-degrading enzymes by Postia placenta
1988 - IRG/WP 1342
The extracellular carbohydrate-degrading enzymes of wood-decay fungi are usually heavily glycosylated and therefore stable under most denaturing conditions. It is unlikely that wood decay can be prevented by simply inactivating these enzymes. Tunicamycin, an antibiotic produced by Streptomyces lysosuperificus, prevents the glycosylation of glycoproteins and can interfere with the secretion of these enzymes. The effect of tunicamycin on the production of extracellular carbohydrate-degrading enzymes of Postia placenta was determined in liquid culture. Enzyme production was inhibited at concentrations of 2.5-5 mg/ml; glycosidases were more sensitive than glycanases. Colony morphology was greatly altered at these concentrations, but dry weights decreased only 20-30%. The thermostabilities of xylanase and a-galactosidase, and the pH stability of xylanase, decreased when formed in the presence of low concentrations of tunicamycin. This suggests that the enzymes are produced in an active but nonglycosylated (or underglycosylated) form. The deglycosylation of glycoproteins may be a physiologically specific means of controlling wood-decay fungi.
J A Micales, T L Highley
Analysis of D-glucose metabolism of wood decay fungi using 13C-NMR and 13C-labeled substrates
2003 - IRG/WP 03-10475
D-Glucose metabolism is thought to be important during wood decay by fungi, not only for anabolic and catabolic purposes of central metabolism, but also as a potential source of peroxide required by extracellular peroxidases. There has been some confusion in the literature as to whether this peroxide-generating activity is of the glucose 1-oxidase or pyranose 2-oxidase (glucose 2-oxidase) type with various fungi or even within the same fungal species. Definitive classification requires accurate identification of the enzymatic products D-glucono-1,5-lactone and D-arabino-2-hexosulose (glucosone) with glucose 1-oxidase and pyranose 2-oxidase, respectively. We used 13C-NMR to distinguish these reactions starting with 13C-labeled glucose. The use of labeled substrates simplifies analysis and greatly increases detection sensitivity without requiring the isolation or derivatization of metabolites. We synthesized 13C-1-glucosone to study subsequent metabolism with crude enzyme preparations. Preliminary results with Phanerochaete chrysosporium are presented.
T H de Koker, M D Mozuch, P J Kersten
Distribution of the three symbiotic protozoa in Formosan subterranean termite, Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae)
1993 - IRG/WP 93-10010
Six colonies (three each from laboratory and field) of Formosan subterranean termite, Coptotermes formosanus Shiraki, were served for investigating the abundance and distribution of three symbiotic protozoa in the hindgut of workers. The total protozoan number amounted to 6,000-10,000 per a worker, and the order of the abundance of the three protozoa and the proportional distribution of each species in the hindgut were common among the colonies. Pseudotrichonympha grassii Koidzumi was the smallest in number (800-2,200 per a worker) and was preferentially distributed in the anterior part of the hindgut. Holomastigotoides hartmanni Koidzumi was medial in number (1,200-3,000), and the distribution was relatively uniform all through the hindgut. Spirotrichonympha leidyi Koidzumi was the most abundant in number (2,800-5,000) and was found mainly in the posterior part. These results appeared to support that the prominent localization of each protozoan species in the worker´s hindgut could be related to the nutritional metabolism in Coptotermes formosanus.
T Yoshimura, K Tsunoda, M Takahashi
The metabolism and comparative elimination of polychlorinated biphenyl congeners in termites
1993 - IRG/WP 93-10038
Termites may serve as a potential supplementary food source for fish, poultry and pigs. Waste paper may be used as a source of food in mass rearing the termites. However, paper products and printing inks contain trace levels of toxic xenobiotics e.g. polychlorinatecl biphenyls (PCBs) and dioxins. This study examined the ability of Mastotermes darwinensis and Coptotermes acinaciformis to metabolise these xenobiotics when fed paper as a food source. A series of PCBs was used as model lipophilic xenobiotics and fed to two species of termite. Extracted whole termites and their faeces were analysed for content of PCBs and metabolites. A phenolic metabolite of 4,4'-dichlorobiphenyl (44-DCB) was extracted and identified from the bodies and faeces of both termite species. 2,2',4,4',5,5'-Hexachlorobiphenyl (224455-HCB) was retained in termite bodies at a significantly higher concentration than 3,3',4,4',5,5'-Hexachlorobiphenyl (334455-HCB) when fed the congeners in paper at the same concentration.
V S Haritos, J R J French, J T Ahokas
Oxalic acid metabolism of Postia placenta
1992 - IRG/WP 92-1566
The oxalic acid metabolism of Postia placenta was studied in liquid culture in order to identify the metabolic pathways of biosynthesis and to determine whether oxalic acid physiology could be correlated with efficiency in wood decay. Oxalic acid production was determined for test strain MAD698 grown in a basal defined medium with a variety of different carbohydrate and nitrogen sources. The highest quantity of oxalic acid was formed in the presence of glucuronate; lower quantities were formed in response to glycolic acid and glyoxylate, suggesting that the predominant pathway of synthesis for oxalic acid is the glyoxylate bypass of the tricarboxylic acid cycle. Little or no oxalic acid was formed when simple sugars served as the carbon source. Ammonium phosphate (monobasic), ammonium chloride, ammonium sulphate, and peptone also stimulated oxalic acid production. An aberrant strain Postia placenta (ME20) that fails to cause significant weight loss in wood produced ten times less oxalic acid in response to glucuronate than MAD698. Strain ME20 also failed to form detectable concentrations of oxalic acid when glycolic acid or glyoxylate were the sole sources of carbon. The inability of ME20 to cause weight loss in wood may be related to a decreased efficiency or defective regulation of the biosynthetic pathway for oxalic acid.
J A Micales
The identification of the carbohydrate degrading enzymes from the crude extract of brown-rot fungus Gloeophyllum trabeum
1991 - IRG/WP 1483
The brown-rot fungus, Gloeophyllum trabeum, produces a pattern of carbohydrate degrading enzymes during the wood decay. In liquid sawdust media the activities of endo-b-1,4-gluganase and endo-b-1,4-xylanase were at the maximum after 5-6 weeks cultivation. The production of enzymes started immediately after inoculation suggesting that the degradation of hemicellulose and easily degradable parts of cellulose is an initial step of wood decomposition.
A-C Ritschkoff, J Buchert, L Viikari
Decomposition and metabolism of gaseous COS by wood rotting fungi
2021 - IRG/WP 21-10978
Previous studies on physiology of wood rotting fungi have mostly focused on the metabolisms of carbon and nitrogen sources. On the other hand, despite of the biological importance of minerals such as sulfur, our knowledge of their metabolic systems is limited. The sulfur source for wood-rotting fungi has been thought to be water-soluble sulfur compounds such as sulfate esters and cysteine, which are present in very small amounts in wood. Recently, our research group has shown that filamentous ascomycetous fungus isolated from soil have the ability to degrade carbonyl sulfide (COS), which is a gaseous sulfur compound, and it can use COS as a sulfur source. Based on the background, in the present study, we hypothesized that the wood rotting fungi also uses a gaseous COS in the air, to grow in wood. In order to prove this hypothesis, we measured the COS-degrading activity of nine wood rotting fungi (brown-rot fungi Gloeophyllum trabeum, Coniophora puteana, Fomitopsis palustris, Fomitopsis pinicola, Neolentinus suffrutescens, Wolphiporia cocos and Serpula lacrymans, and white-rot fungi Trametes versicolor and, Pleurotus ostreatus) and found that all of them had COS-degrading activity. Among the above fungi, G. trabeum, a model brown-rot fungus, was used to investigate the effect of COS addition on the growth of the fungus. In addition, to clarify the effect of COS addition on metabolites, metabolome analysis focusing on sulfur-containing compounds was conducted, and several sulfur-containing metabolites and compounds involved in sulfur metabolism were detected. These results suggest the existence of a novel sulfur acquisition pathway using gaseous COS by wood rotting fungi
R Iizuka, O Iwao, Y Katayama, M Yoshida