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1.
Basidiomycota brown rot fungus (Fomitopsis pinicola) and two white rot fungi (Phlebia radiata, Trichaptum abietinum) were cultivated on thin slices of spruce wood individually and in interspecies combinations. Within 12 months, F. pinicola substantially decomposed spruce wood observed as mass loss, also in three-species combinations. However, white rot fungi through hyphal interactions negatively affected the brown-rot indicative iron reduction capacity of F. pinicola. Decay-signature gene expression in mycelial interaction zones indicated suppression of brown rot mechanism but stimulation of enzymatic white-rot lignin attack by P. radiata. Wood ultrastructure imaging showed white-rot dominance in the fungal combinations, whereas destructive brown-rot was evident with F. pinicola alone. Our results confirm the dynamic pattern of enzyme production in fungal combinations, and transition from brown to white rot decomposition metabolism during the late stage of wood decay after one year of interspecific interactions.  相似文献   

2.
Wood-decaying basidiomycetes are some of the most effective bioconverters of lignocellulose in nature, however the way they alter wood crystalline cellulose on a molecular level is still not well understood. To address this, we examined and compared changes in wood undergoing decay by two species of brown rot fungi, Gloeophyllum trabeum and Meruliporia incrassata, and two species of white rot fungi, Irpex lacteus and Pycnoporus sanguineus, using X-ray diffraction (XRD) and 13C solid-state nuclear magnetic resonance (NMR) spectroscopy. The overall percent crystallinity in wood undergoing decay by M. incrassata, G. trabeum, and I. lacteus appeared to decrease according to the stage of decay, while in wood decayed by P. sanguineus the crystallinity was found to increase during some stages of degradation. This result is suggested to be potentially due to the different decay strategies employed by these fungi. The average spacing between the 200 cellulose crystal planes was significantly decreased in wood degraded by brown rot, whereas changes observed in wood degraded by the two white rot fungi examined varied according to the selectivity for lignin. The conclusions were supported by a quantitative analysis of the structural components in the wood before and during decay confirming the distinct differences observed for brown and white rot fungi. The results from this study were consistent with differences in degradation methods previously reported among fungal species, specifically more non-enzymatic degradation in brown rot versus more enzymatic degradation in white rot.  相似文献   

3.
We examined whether sporocarp carbon and nitrogen isotope ratios (δ13C and δ15N values) reflected different functional strategies in 15 species of wood decay fungi. In Finnish Picea abies forests, we compared sporocarp δ13C and δ15N against log diameter, proximity to ground, and three wood decay types, specifically brown rot, nonselective white rot, and selective white rot (targeting hemicellulose and lignin preferentially). In regression analysis (adjusted r2 = 0.576), species accounted for 31% of variability in δ13C, with factors influencing wood δ13C accounting for the remainder. Brown rot fungi and three white rot fungi that selectively attacked hemicellulose (Heterobasidion parviporum, Phellopilus nigrolimitatus, and Trichaptum abietinum) were higher in δ13C than nonselective white rot fungi. This was attributed to greater assimilation of 13C-enriched pentoses from hemicellulose by these fungi. The pathogenic white rot fungus Heterobasidion parviporum had higher δ15N with proximity to ground and increasing log diameter. This suggested that 15N-enriched soil N contributed to decomposing logs and that Heterobasidion growing from a bigger resource base had increased access to soil N. These isotopic patterns accordingly reflected both functional diversity of wood decay fungi and site-specific factors.  相似文献   

4.
The white rot fungi used in this study caused two different forms of degradation. Phanerochaete chrysosporium, strain BKM-F-1767, and Phellinus pini caused a preferential removal of lignin from birch wood, whereas Trametes (Coriolus) versicolor caused a nonselective attack of all cell wall components. Use of polyclonal antisera to H8 lignin peroxidase and monoclonal antisera to H2 lignin peroxidase followed by immunogold labeling with protein A-gold or protein G-gold, respectively, showed lignin peroxidase extra-and intracellularly to fungal hyphae and within the delignified cell walls after 12 weeks of laboratory decay. Lignin peroxidase was localized at sites within the cell wall where electron-dense areas of the lignified cell wall layers remained. In wood decayed by Trametes versicolor, lignin peroxidase was located primarily along the surface of eroded cell walls. No lignin peroxidase was evident in brown-rotted wood, but slight labeling occurred within hyphal cells. Use of polyclonal antisera to xylanase followed by immunogold labeling showed intense labeling on fungal hyphae and surrounding slime layers and within the woody cell wall, where evidence of degradation was apparent. Colloidal-gold-labeled xylanase was prevalent in wood decayed by all fungi used in this study. Areas of the wood with early stages of cell wall decay had the greatest concentration of gold particles, while little labeling occurred in cells in advanced stages of decay by brown or white rot fungi.  相似文献   

5.
We incubated 196 large-diameter aspen (Populus tremuloides), birch (Betula papyrifera), and pine (Pinus taeda) logs on the FACE Wood Decomposition Experiment encompassing eight climatically-distinct forest sites in the United States. We sampled dead wood from these large-diameter logs after 2 to 6 y of decomposition and determined wood rot type as a continuous variable using the lignin loss/density loss ratio (L/D) and assessed wood-rotting fungal guilds using high-throughput amplicon sequencing (HTAS) of the ITS-2 marker. We found L/D values in line with a white rot dominance in all three tree species, with pine having lower L/D values than aspen and birch. Based on HTAS data, white rot fungi were the most abundant and diverse wood-rotting fungal guild, and soft rot fungi were more abundant and diverse than brown rot fungi in logs with low L/D values. For aspen and birch logs, decay type was related to the wood density at sampling. For the pine logs, decay type was associated with the balance between white and brown/soft rot fungi abundance and OTU richness. Our results demonstrate that decay type is governed by biotic and abiotic factors, which vary by tree species.  相似文献   

6.
The brown rot fungus Wolfiporia cocos and the selective white rot fungus Perenniporia medulla-panis produce peptides and phenolate-derivative compounds as low molecular weight Fe3+-reductants. Phenolates were the major compounds with Fe3+-reducing activity in both fungi and displayed Fe3+-reducing activity at pH 2.0 and 4.5 in the absence and presence of oxalic acid. The chemical structures of these compounds were identified. Together with Fe3+ and H2O2 (mediated Fenton reaction) they produced oxygen radicals that oxidized lignocellulosic polysaccharides and lignin extensively in vitro under conditions similar to those found in vivo. These results indicate that, in addition to the extensively studied Gloeophyllum trabeum—a model brown rot fungus—other brown rot fungi as well as selective white rot fungi, possess the means to promote Fenton chemistry to degrade cellulose and hemicellulose, and to modify lignin. Moreover, new information is provided, particularly regarding how lignin is attacked, and either repolymerized or solubilized depending on the type of fungal attack, and suggests a new pathway for selective white rot degradation of wood. The importance of Fenton reactions mediated by phenolates operating separately or synergistically with carbohydrate-degrading enzymes in brown rot fungi, and lignin-modifying enzymes in white rot fungi is discussed. This research improves our understanding of natural processes in carbon cycling in the environment, which may enable the exploration of novel methods for bioconversion of lignocellulose in the production of biofuels or polymers, in addition to the development of new and better ways to protect wood from degradation by microorganisms.  相似文献   

7.
In forest ecosystems, fungi are the key actors in wood decay. They have the capability to degrade lignified substrates and the woody biomass of coniferous forests, with brown rot fungi being common colonizers. Brown rots are typically involved in the earliest phase of lignocellulose breakdown, which therefore influences colonization by other microorganisms. However, few studies have focused on the impact of introducing decayed wood into forest environments to gauge successional colonization by natural bacterial and fungal communities following partial decay. This study aimed to address this issue by investigating the bacterial and fungal colonization of Norway spruce (Picea abies) wood, after intermediate and advanced laboratory-based, pre-decay, by the brown rot fungus Gloeophyllum trabeum. Using Illumina metabarcoding, the in situ colonization of the wood blocks was monitored 70 days after the blocks were placed on the forest floor and covered with litter. We observed significant changes in the bacterial and fungal communities associated with the pre-decayed stage. Further, the wood substrate condition acted as a gatekeeper by reducing richness for both microbial communities and diversity of fungal communities. Our data also suggest that the growth of some fungal and bacterial species was driven by similar environmental conditions.  相似文献   

8.
A novel two-stage, whole organism fungal biopulping method was examined for increasing the yield of enzymatic hydrolysis of wood into soluble glucose. Liriodendron tulipifera wood chips (1 g) were exposed to liquid culture suspensions of white rot (Ceriporiopsis subvermispora) or brown rot (Postia placenta) fungi and incubated at 28 °C, either alone in single-stage 30 day (one fungal species applied) or two-stage 60 day (both fungal species applied in alternative succession) treatments. Fungi grew in all treatments, but did not significantly decrease the percent carbohydrate content of the wood. Two-stage treatments differed significantly in mass loss depending on order of exposure, suggesting additive or inhibitory fungal interactions occurred. Treatments consisting of C. subvermispora followed by P. placenta exhibited 6 ± 0.5% mass loss and increased the yield of enzymatic hydrolysis by 67-119%. This significant hydrolysis improvement suggests that fungal biopulping technologies could support commercial lignocellulosic ethanol production efforts if further developed.  相似文献   

9.
Most Boletaceae form ectomycorrhizas but species in two sister groups (subfamily Chalciporoideae and the genus Pseudoboletus) have unclear trophic modes and are putatively mycoparasitic. Chalciporoideae is the earliest diverging lineage in Boletaceae and includes Chalciporus and Buchwaldoboletus. Buchwaldoboletus species fruit on wood and were thought to be saprobes, but the type species Buchwaldoboletus lignicola is mycoparasitic on the wood decay fungus Phaeolus schweinitzii. However, the nutritional mode and host range of B. lignicola and other Buchwaldoboletus remain unclear. We obtained fresh collections and axenic cultures of B. lignicola, B. hemichrysus and B. sphaerocephalus from the southeastern USA. We use cultures to examine the phylogenetic relationships among taxa in Chalciporoideae, elucidate the trophic mode of Buchwaldoboletus species and test the effect that Buchwaldoboletus species have on wood decay. Our analysis supports the hypothesis that the Chalciporus lineage is sister to all other Boletaceae but suggests that Buchwaldoboletus is not monophyletic. Confrontation experiments on agar suggest that Buchwaldoboletus species might parasitize a wide range of decay fungi. Buchwaldoboletus hemichrysus and B. sphaerocephalus produce abundant conidia in culture whereas the more distantly related B. lignicola produces sclerotia. Wood decay assays show that Buchwaldoboletus species did not have a significant effect on the decay caused by wood decay fungi. Interestingly, when B. lignicola or B. hemichrysus were inoculated alone on wood both species decayed wood, producing a brown rot that can cause 35–65% mass loss over 6 months. Our results suggest that Buchwaldoboletus species have a dual trophic mode as saprobes and mycoparasites.  相似文献   

10.
Several analytical methods were compared to evaluate characteristic wood decaying fungi for their potential to depolymerise lignin on spruce wood particles. Wood samples were treated with the white rot fungi Phlebia brevispora, Ceriporiopsis subvermispora, Merulius tremellosus, Pycnoporus sanguineus, Trametes pubescens and with the brown rot fungus Gloeophyllum trabeum. The UV absorbancies of crude ethanol extracts, total extractives content from sequential extraction, ligninolytic enzyme activities, lignin solubilisation and decrease of lignin content were compared. It was shown, that, in early decay stages, UV absorbancies of crude ethanol extracts and total extractives content correlate well with lignin degradation, increase of acid soluble lignin and increased production of ligninolytic enzymes (total peroxidase). Lignin content was determined using FT-NIR spectroscopy as well as by wet-chemical analysis, indicating a very good correlation between the two methods. According to the different analytical methods, the tested fungi can be classified into three categories based on their characteristic behaviour: brown rot, “slow” and “fast” white rot.  相似文献   

11.
Interest in the mechanisms of wood-degrading fungi has grown in tandem with lignocellulose bioconversion efforts, yet many potential biomass feedstocks are non-woody. Using corn stover (Zea mays) as a substrate, we tracked degradative capacities among brown rot fungi from the Antrodia clade, including Postia placenta, the first brown rot fungus to have its genome sequenced. Decay dynamics were compared against Gloeophyllum trabeum from the Gloeophyllum clade. Weight loss induced by P. placenta (6.2 %) and five other Antrodia clade isolates (average 7.4 %) on corn stalk after 12 weeks demonstrated inefficiency among these fungi, relative to decay induced by G. trabeum (44.4 %). Using aspen (Populus sp.) as a woody substrate resulted in, on average, a fourfold increase in weight loss induced by Antrodia clade fungi, while G. trabeum results matched those on stover. The sequence and trajectories of chemical constituent losses differed as a function of substrate but not fungal clade. Instead, chemical data suggest that characters unique to stover limit decay by the Antrodia clade, rather than disparities in growth rate or extractives toxicity. High p-coumaryl lignin content, lacking the methoxy groups characteristically cleaved during brown rot, is among potential rate-distinguishing characters in grasses. This ineptitude among Antrodia clade fungi on grasses was supported by meta-analysis of other unrelated studies using grass substrates. Concerning application, results expose a problem if adopting the strategy of the model decay fungus P. placenta to treat corn stover, a widely available plant feedstock. Overall, the results insinuate phylogenetically distinct modes of brown rot and demonstrate the benefit of using non-woody substrates to probe wood degradation mechanisms.  相似文献   

12.
Progressive changes in solubility characteristics and lignin content of Pinus radiata sapwood were assessed when small blocks were subjected to decay by brown (Gloeophyllum trabeum) and white (Perenniporia tephropora) rot fungi. The brown rot species removed lignin in approximate proportion to weight loss up to 10%; thereafter the amount of lignin altered little. In contrast, the decline in lignin content was near linear for P. tephropora. Increases in solubility (particularly with hot water and dilute alkali), in sugar content and in the acidity of aqueous extracts were recorded in wood blocks decayed to 15–20% weight loss. While these effects were more pronounced in samples decayed by G. trabeum, it appears that with both organisms structural components were degraded faster than the products could be utilised. In this case, cell wall chemistry may not have been a major determinant of weight losses.  相似文献   

13.
Wood decay under the microscope   总被引:3,自引:0,他引:3  
Many aspects of the interactions between host wood structure and fungal activity can be revealed by high resolution light microscopy, and this technique has provided much of the information discussed here. A wide range of different types of decay can result from permutations of host species, fungal species and conditions within wood. Within this spectrum, three main types are commonly recognised: brown rot, white rot and soft rot. The present review explores parts of the range of variation that each of these encompasses and emphasizes that degradation modes appear to reflect a co-evolutionary adaptation of decay fungi to different wood species or the lignin composition within more primitive and advanced wood cell types. One objective of this review is to provide evidence that the terms brown rot, white rot and soft rot may not be obsolete, but rigid definitions for fungi that are placed into these categories may be less appropriate than thought previously. Detailed knowledge of decomposition processes does not only aid prognosis of decay development in living trees for hazard assessment but also allows the identification of wood decay fungi that can be used for biotechnology processes in the wood industry. In contrast to bacteria or commercial enzymes, hyphae can completely ramify through solid wood. In this review evidence is provided that wood decay fungi can effectively induce permeability changes in gymnospermous heartwood or can be applied to facilitate the identification of tree rings in diffuse porous wood of angiosperms. The specificity of their enzymes and the mild conditions under which degradation proceeds is partly detrimental for trees, but also make wood decay fungi potentially efficient biotechnological tools.  相似文献   

14.
This study evaluated the decay resistance of ash (Fraxinus excelsior L.), beech (Fagus sylvatica L.), and maple (Acer platanoides L.) wood impregnated by a full cell process with N-methylol melamine (NMM) and combined NMM-metal complex dye (NMM-BS) in aqueous solutions. Basidiomycete decay testing involved incubation with Coniophora puteana (brown rot) and Trametes versicolor (white rot) according to a modified EN 113 (1996) standard, while for the soft rot fungal resistance was evaluated following the standard ENv 807 (2001). NMM and NMM-BS modifications at a WPG range of 7–11% provided decay protection against brown rot resulting in a mass loss less than the required limit (3%). The NMM and NMM-BS modified wood showed increased resistance to white rot decay; however, a higher WPG is needed to prohibit attack from this hardwood specific fungus. The metal-complex dye alone revealed biocidal effects against basidiomycetes. An increased WPG in NMM or NMM-BS had a positive impact against soft rot decay and the lowest mass losses after 32 weeks of exposure were obtained with NMM modification at about 18–21% WPG. NMM modification at this WPG range, however, was not sufficient to protect the wood from soft rot decay. The wood of beech and maple showed slightly higher resistance to all decay types than ash, probably due to the poorer degree of modification of the latter.  相似文献   

15.
Importance of boron compounds in wood preservation is increasing due to their low environmental impact, high efficacy and the fact that many other active ingredients have been removed from the market after the introduction of the Biocidal Products Directive. The most important drawback of boron is prominent leaching in wet environment. In order to improve their fixation, and performance against wood decay fungi, boric acid was combined with montan wax emulsion. Possible synergistic effects of boric acid and montan wax were determined according to modified EN 113 procedure. Norway spruce and beech wood specimens were exposed to three white rot (Trametes versicolor, Pleurotus ostreatus and Hypoxylon fragiforme) and brown rot wood decay fungi (Gloeophyllum trabeum, Antrodia vaillantii and Serpula lacrymans) for 12 weeks. Boron leaching from vacuum/pressure treated Norway spruce wood was determined according to the continuous (EN 84 and ENV 1250-2) and non-continuous (OECD and prCEN/TS 15119-1) procedures. Boron was determined with ICP mass spectrometry in collected leachates. The results of the fungicidal tests clearly showed that montan wax emulsion and boric acid act synergistically against tested wood decay fungi. Approximately 50% lower boric acid retentions are required in combination with montan wax emulsions to achieve sufficient protection against wood rotting fungi. However, it is even more important that all leaching tests performed proved that the addition of montan wax decreased boron leaching from impregnated specimens for 20% up to 50%.  相似文献   

16.
Production and Degradation of Oxalic Acid by Brown Rot Fungi   总被引:4,自引:3,他引:1       下载免费PDF全文
Our results show that all of the brown rot fungi tested produce oxalic acid in liquid as well as in semisolid cultures. Gloeophyllum trabeum, which accumulates the lowest amount of oxalic acid during decay of pine holocellulose, showed the highest polysaccharide-depolymerizing activity. Semisolid cultures inoculated with this fungus rapidly converted 14C-labeled oxalic acid to CO2 during cellulose depolymerization. The other brown rot fungi also oxidized 14C-labeled oxalic acid, although less rapidly. In contrast, semisolid cultures inoculated with the white rot fungus Coriolus versicolor did not significantly catabolize the acid and did not depolymerize the holocellulose during decay. Semisolid cultures of G. trabeum amended with desferrioxamine, a specific iron-chelating agent, were unable to lower the degree of polymerization of cellulose or to oxidize 14C-labeled oxalic acid to the extent or at the rate that control cultures did. These results suggest that both iron and oxalic acid are involved in cellulose depolymerization by brown rot fungi.  相似文献   

17.
In this work, the resistance of black pine wood (Pinus nigra L.) vacuum-treated with zinc oxide, zinc borate and copper oxide nanoparticles against mold and decay fungi and the subterranean termites was evaluated. Some of the nanocompounds tested were forced with acrylic emulsions to avoid leaching. Results showed that mold fungi were slightly inhibited by nanozinc borate, while the other nanometal preparations did not inhibit mold fungi. Mass loss from fungal attack by Trametes versicolor was significantly inhibited by the zinc-based preparations, while the brown-rot fungus, Tyromyces palustris was not inhibited by the nanometal treatments. Notably, nanozinc borate plus acrylic emulsion imparted very high resistance in pine wood to the white-rot fungus, T. versicolor with a mass loss of 1.8%. Following leaching, all pine specimens treated with nanozinc borate, with or without acrylic emulsion, strongly inhibited termite feeding, i.e. mass losses varying at 5.2–5.4%. In contrast, the copper-based treatments were much less effective against the subterranean termites, Coptotermes formosanus. In general, nanozinc borate possessed favorable properties, that is, inhibition of termite feeding and decay by T. versicolor.  相似文献   

18.
White rot fungi are good lignin degraders and have the potential to be used in industry. In the present work, Phellinus sp., Daedalea sp., Trametes versicolor and Pycnoporus coccineus were selected due to their relatively high ligninolytic enzyme activity, and grown on Acacia mangium wood chips under solid state fermentation. Results obtained showed that manganese peroxidase produced is far more compared to lignin peroxidase, suggesting that MnP might be the predominating enzymes causing lignin degradation in Acacia mangium wood chips. Cellulase enzyme assays showed that no significant cellulase activity was detected in the enzyme preparation of T. versicolor and Phellinus sp. This low cellulolytic activity further suggests that these two white rot strains are of more interest in lignin degradation. The results on lignin losses showed 20–30% of lignin breakdown at 60 days of biodegradation. The highest lignin loss was found in Acacia mangium biotreated with T. versicolor after 60 days and recorded 26.9%, corresponding to the percentage of their wood weight loss recorded followed by P. coccineus. In general, lignin degradation was only significant from 20 days onwards. The overall percentage of lignin weight loss was within the range of 1.02–26.90% over the biodegradation periods. Microscopic observations conducted using scanning electron microscope showed that T. versicolor, P. coccineus, Daedalea sp. and Phellinus sp. had caused lignin degradation in Acacia mangium wood chips.  相似文献   

19.
Due to their outstanding capability of degrading the recalcitrant biomacromolecule lignin, white rot fungi have been attracting interest for several technological applications in mechanical pulping and wood surface modification. However, little is known about the time course of delignification in early stages of colonisation of wood by these fungi. Using a Fourier transform near infrared (FT-NIR) spectroscopic technique, lignin loss of sterilised spruce wood shavings (0.4–2.0 mm particle size) that had been degraded by various species of white rot fungi could be monitored already during the first 2 weeks. The delignification kinetics of Dichomitus squalens, three Phlebia species (Phlebia brevispora, Phlebia radiata and Phlebia tremellosa), three strains of Ceriporiopsis subvermispora as well as the white rot ascomycete Hypoxylon fragiforme and the basidiomycete Oxyporus latemarginatus were determined. Each of the fungi tested was able to reduce the lignin content of spruce wood significantly during the first week. The amount of delignification achieved by the selected white rot fungi after 2 weeks ranged from 7.2% for C. subvermispora (FPL 105.752) to 2.5% for P. radiata. Delignification was significant (P = 95%) already after 3 days treatment with C. subvermispora and P. tremellosa. Activities of extracellular ligninolytic enzymes (laccase, manganese peroxidase and/or lignin peroxidase), expressed by each of the tested fungi, were determined. Lignin was degraded when peroxidase activity was detected in the fungal cultures, but only a low level of correlation between enzyme activities and the extent of delignification was found.  相似文献   

20.
We assessed 62 fungal strains in 31 species of wood decay fungi in the ability to decompose wood blocks of Japanese beech (Fagus crenata) under a pure culture condition. Fungi were collected in a cool temperate beech forest in Japan and isolated from the inside of beech logs and from sporocarps fruiting on logs and snags of beech that were different in diameter and decay class. Fungi in Holobasidiomycetidae showed marked decomposition of lignin and carbohydrate. These fungi were divided into three groups according to the pattern of lignin and carbohydrate utilization. Phanerochaete filamentosa decomposed lignin selectively. Lampteromyces japonicus, Steccherinum rhois, Trichaptum biforme, Stereum ostrea, Mycena haematopoda, Antrodiella albocinnamomea, Daedalea dickinsii, Daedaleopsis tricolor, Ganoderma tsunodae, and Trametes versicolor decomposed lignin and carbohydrates simultaneously. Psathyrella candolleana, Lenzites betulinus, and Trametes hirsuta decomposed carbohydrates selectively. Species in the Phragmobasidiomycetidae and in the Ascomycota caused low mass loss of wood.  相似文献   

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