White-rot Trametes Versicolor Research Articles

A reverse chemical ecology approach to explore wood natural durability.

SummaryThe natural durability of wood species, defined as their inherent resistance to wood‐destroying agents, is a complex phenomenon depending on many biotic and abiotic factors. Besides the presence of recalcitrant polymers, the presence of compounds with antimicrobial properties is known to be important to explain wood durability. Based on the advancement in our understanding of fungal detoxification systems, a reverse chemical ecology approach was proposed to explore wood natural durability using fungal glutathione transferases. A set of six glutathione transferases from the white‐rot Trametes versicolor were used as targets to test wood extracts from seventeen French Guiana neotropical species. Fluorescent thermal shift assays quantified interactions between fungal glutathione transferases and these extracts. From these data, a model combining this approach and wood density significantly predicts the wood natural durability of the species tested previously using long‐term soil bed tests. Overall, our findings confirm that detoxification systems could be used to explore the chemical environment encountered by wood‐decaying fungi and also wood natural durability.

Effect of burgundy solid extracted from Eastern Red Cedar heartwood on subterranean termites and Wood-decay fungi

Eastern red cedar (ERC) is an abundant natural resource in the U.S. and has been investigated for the extraction of cedarwood oil (CWO) and CWO bioactivity, particularly its use to protect wood against termites and decay fungi. Methanol extraction of ERC sawdust gives a burgundy-colored oil (BO) that is comprised of both CWO and a burgundy solid (BS). The BO was significantly more inhibitory against two species of white-rot decay fungi than CWO alone, suggesting the BS itself might have inhibitory bioactivity. This study investigated the wood preservation properties of the BS alone, in combination with CWO and in conjunction with an amylose inclusion complex (AIC) against termites, brown-rot decay fungi and white-rot decay fungi. Wood was treated by vacuum/pressure impregnation and tested for resistance to subterranean termites and four species of decay fungi. The AIC alone made wood less palatable (16% mass loss versus 32% for H2O) and more toxic (32% mortality versus 26% for H2O) to termites but did not inhibit either brown-rot fungi nor the white-rot Trametes versicolor but did inhibit the white-rot Irpex lacteus (49% mass loss versus 65% for H2O). The CWO led to both lower wood mass loss by termites and higher termite mortality as well as having an inhibitory effect on the white-rot decay fungi. However, a combination of AIC and CWO was necessary to have an inhibitory effect on the brown-rot fungi. The addition of BS to the AIC had a minor inhibitory effect on wood mass loss by termites (11% versus 16% for AIC) but did not inhibit either brown-rot fungi nor the white-rot I. lacteus. The addition of BS to the AIC decreased wood mass loss by the white-rot T. versicolor (38% versus 49% for AIC). Wood blocks impregnated with the combination of the AIC, CWO and BS resulted in the highest termite mortality (i.e., 100%), lowest percentage wood mass loss for the termites (i.e., 6%) and lowest percentage wood mass losses for all four species of wood decay fungi studied (less than 20% overall).

Durabilidade natural das madeiras de Apuleia leiocarpa, Astronium lecointei e Enterolobium schomburgkii ao fungo apodrecedor Trametes versicolor

O presente estudo teve por objetivo avaliar a durabilidade natural das madeiras de Apuleia leiocarpa (grápia), Astronium lecointei (muiracatiara) e Enterolobium schomburgkii (fava-orelha-de-negro) ao ataque do fungo causador da podridão branca Trametes versicolor (Linnaeus ex Fries) Pilat, pelo ensaio de apodrecimento acelerado. Foram utilizadas 15 amostras de cerne de cada espécie, nas dimensões 2,5 x 2,5 x 0,9 cm (radial, tangencial e axial, respectivamente). Essas permaneceram durante 16 semanas em incubadora sob ataque do fungo. Após o período de ataque, determinaram-se a perda de massa e a referida classe de durabilidade natural. E. schomburgkii apresentou a maior média de perda de massa (17,5%), seguida de A. lecointei (15,5%), sendo classificadas como resistentes a T. versicolor. A. leiocarpa apresentou maior durabilidade (10,6% de perda de massa), sendo classificada como altamente resistente. A madeira de A. leiocarpa diferiu estatisticamente das demais, indicando potencial de maior durabilidade quando disposta em condições que favoreçam a desenvolvimento deste xilófago.

Fungal Glutathione Transferases as Tools to Explore the Chemical Diversity of Amazonian Wood Extractives

The natural durability of wood is linked to its chemical composition and in particular the presence of metabolites called extractives that often possess chemical reactivity. For dealing with these compounds, wood degraders have developed detoxification systems usually involving enzyme families. Among these enzymes, glutathione transferases (GSTs) are involved in the decrease of the reactivity of toxic compounds. In this study, the hypothesis that the detoxification systems of wood decaying fungi could be indicators of the chemical reactivity of wood extracts has been tested. This approach has been evaluated using 32 wood extracts coming from French Guiana species, testing their antimicrobial ability, antioxidative properties, and reactivity against six GSTs from the white rot Trametes versicolor. From the obtained data, a significant correlation between the antimicrobial and antioxidative properties of the tested wood extracts and GST interactions was established. In addition, the chemical analysis performed on one of the most reactive extracts (an acetonic extract of Bagassa guianensis) has demonstrated oxyresveratrol as a major constituent. We were able to cocrystallize one GST with this commercially interesting compound. Taken together, the presented data support the hypothesis that detoxifying enzymes could be used to identify the presence of molecules of industrial interest in wood extracts.

Effectiveness of acetic, propionic and butyric anhydrides to protect rubberwood from decayed by white rot Trametes versicolor

Fresh rubber tree was harvested, cut into sized (100 cm x 14 cm x 25 mm) (l x w x t) and kiln dried (10-12 %) MC. The specimen sized of 5 mm x 20 mm x 20 mm (l x w x t) were prepared, undergone soxhlet extraction with toluene/methanol/acetone (4:1:1 by volume) for 8 hours, followed by oven dried at 103 °C for 24 hours and cooled in silica gel. The specimens were vacuum impregnated and then reacted with anhydrides for times ranging from 0.25 to 24 hours at 120 °C. The weight percent gain (WPG) was calculated and the chemical bonding was analysed with FTIR. All the specimens were leached in dionised water according to EN 84 (1997) and exposed to white rot in incubation room set at 22 °C (16 weeks). The study was found that modification only managed to reduce the rate of decay; without totally protected the rubberwood. Modified rubberwood was still classified as durability class 1 when compared to scott pine and beech woods. The final MC had a positive correlation with the weight loss following decay. The SEM showed that the hyphae were penetrated in the cells in both rubberwood.

Molecular recognition of wood polyphenols by phase II detoxification enzymes of the white rot Trametes versicolor

Wood decay fungi have complex detoxification systems that enable them to cope with secondary metabolites produced by plants. Although the number of genes encoding for glutathione transferases is especially expanded in lignolytic fungi, little is known about their target molecules. In this study, by combining biochemical, enzymatic and structural approaches, interactions between polyphenols and six glutathione transferases from the white-rot fungus Trametes versicolor have been demonstrated. Two isoforms, named TvGSTO3S and TvGSTO6S have been deeply studied at the structural level. Each isoform shows two distinct ligand-binding sites, a narrow L-site at the dimer interface and a peculiar deep hydrophobic H-site. In TvGSTO3S, the latter appears optimized for aromatic ligand binding such as hydroxybenzophenones. Affinity crystallography revealed that this H-site retains the flavonoid dihydrowogonin from a partially purified wild-cherry extract. Besides, TvGSTO6S binds two molecules of the flavonoid naringenin in the L-site. These data suggest that TvGSTO isoforms could interact with plant polyphenols released during wood degradation.

Improvement in the enzymatic hydrolysis of biofuel substrate by a combined thermochemical and fungal pretreatment

Pretreatment is a critical step in the enzymatic conversion of lignocellulosic substrate to sugars. A unique pretreatment sequence involving thermochemical treatment (steam explosion) followed by biological treatment (fungal exposure) was evaluated for Pinus radiata as a biofuel substrate. The effect of biological treatment using the white rot Trametes versicolor was investigated on control (sapwood blocks) and steam-exploded wood (SEW) for changes in the profile of fungal enzyme activity and lignocellulose composition. The results indicated that compared to blocks, Trametes versicolor expressed more lignocellulose-degrading enzymes when grown on SEW for 6 and 12 weeks. After fungal exposure, the biomass was mixed with a commercial enzyme cocktail for enzymatic hydrolysis. The maximum conversion of biomass to sugars was obtained for Trametes versicolor-treated SEW, with a yield of 4.80 g of glucose l−1, which is greater compared to that obtained from non-fungal-treated SEW (3.80 g of glucose l−1) and Trametes versicolor-treated sapwood blocks (0.80 g of glucose l−1). Examination by microscopy suggests relative increase in the porosity of SEW after fungal treatment, and compositional analysis indicates reduction in lignin content. Both these factors are likely to contribute to the improved hydrolysis of SEW.

Influence of the thermo-hydro-mechanical treatments of wood on the performance against wood-degrading fungi

Hybrid poplar (Populus deltoides × Populus trichocarpa) and Douglas-fir (Pseudotsuga menziesii) wood specimens were densified with three variations of thermo-hydro-mechanical (THM) treatment. The THM treatments differed in the steam environment, including transient steam (TS), saturated steam (SS), and saturated steam with 1-min post–heat treatment at 200 °C (SS+PHT). The bending properties, FTIR spectra, and colour of the THM wood specimens were studied before and after exposure to two different wood decay fungi, brown rot Gloeophyllum trabeum, and white rot Trametes versicolor. The results showed that the performance of densified hybrid poplar wood was considerably poorer than the performance of Douglas-fir heartwood. The FTIR spectra measurements did not show changes in the densified hybrid poplar wood, while some changes were evident in densified Douglas-fir specimens. After fungal degradation, the most prominent changes were observed on the SS+PHT specimens. Colour is one of the most important parameter predominantly influenced by the wood species and the intensity of the densification process for both wood species, while after fungal exposure, the colour of all densified Douglas-fir specimens obtained more or less the same appearance, and densified hybrid poplar specimens resulted in lighter colour tones, indicating that the pattern of degradation of the densified and non-densified specimens are similar. The 3-point bending test results determined that the THM treatment significantly increased the modulus of rupture (MOR) and modulus of elasticity (MOE) of the densified wood specimens, while fungal exposure decreased the MOE and MOR in hybrid poplar and Douglas-fir specimens.

Comparative natural durability of five wood species from Mozambique

The objective of this study was to evaluate the natural durability of five lesser-utilized wood species from Mozambique. Both laboratory methods and field tests were applied for assessing wood decay of muanga ( Pericopsis angolensis), metil ( Sterculia appendiculata), namuno ( Acacia nigrescens), ncurri ( Icuria dunensis), and ntholo ( Pseudolachnostylis maprounaefolia). Laboratory tests involved soft-, brown-, and white-rot fungi and termites. Heart- and sapwood of ncurri and ntholo were exposed in above-ground field tests; additionally, all species were exposed to in-ground contact tests. The results indicated that namuno, muanga, ncurri, and ntholo are resistant to soft-, brown- and white-rot fungi and the termite species Reticulitermes grassea and Mastotermes darwiniensis. Comparatively, soft-rot caused more severe decay on the studied wood species than did basidiomycete fungi. The brown-rot fungi Coniophora puteana, Gloeophiyllum trabeum, and Postia placenta caused less decay on the tested species than did the white-rot Trametes versicolor. Metil was not resistant to any of the mentioned hazards. Therefore, this species is not recommendable for exterior use if untreated.

Effect of fungal pretreatment of wood on successional decay by several inky cap mushroom species

To explore the effect of fungal pretreatments on secondary inky cap decay, field degraded red maple sapwood blocks were exposed to Coprinoid fungi in pure culture decay tests. No significant decay in field degraded blocks was produced by the Coprinopsis or Coprinus isolates tested, but most Coprinellus isolates produced additional degradation in wood blocks previously decayed by 4–10 years of field exposure, with the greatest weight losses observed in blocks subjected to 10 years of field decay. The brown rot Gloeophyllum trabeum and white rot Trametes versicolor were used to pre-treat freshly cut red maple and poplar blocks to explore the effect of laboratory fungal pretreatment on subsequent inky cap decay. Brown rot pretreatment significantly increased subsequent decay of both wood types by most of the inky cap isolates tested. White rot pretreatments did not affect subsequent decay by Coprinopsis or Coprinus isolates but significantly increased decay by the Coprinellus radians isolates tested. Inky caps, particularly Coprinellus species, are characterized as late stage decay fungi known to degrade wood that has been chemically and physically modified by other degradative processes.

Initial stages of Fagus sylvatica wood colonization by the white-rot basidiomycete Trametes versicolor: Enzymatic characterization

The initial stages of wood colonization and degradation by the white-rot Trametes versicolor have been investigated. T. versicolor was grown on Fagus sylvatica wood chips under solid-state fermentation in the presence of malt agar. The beginning of the colonization process was not associated with peroxidases production or hydrolytic activity. In contrast, a sharp induction of laccase expression was observed during the first colonization days. This induction is not due solely to fungal growth on wood chips since similar data were obtained in the presence of biocide (propiconazole)-treated wood, suggesting that enzyme production is due at least in part to the mycelium surrounding wood chips using nutrients from malt agar medium. Laccase production correlated with wood acetone extractives degradation, in particular with the oxidation of catechin, a major compound of beech extracts. In complementary experiments, wood-extracted laccases were shown to be active with wood acetone extracts and pure catechin. Furthermore, wood extractives induced laccase expression. Taken together, these data suggest that the initial stages of wood colonization on malt agar by T. versicolor correlate with wood extractives degradation requiring laccase activity, whereas the other wood-degrading systems (peroxidases and polysaccharides hydrolases) are still repressed.

Natural and preservative-treated durability of Populus nigra cv Italica timber grown in Santa Cruz Province, Argentina

Populus nigra cv Italica (Alamo criollo) is the main species planted for windbreaks in Santa Cruz Province (Argentina). Alamo has been a traditional source of poles for rural constructions in southern Patagonia. The objective of this work was to evaluate the natural and CCA-treated durability of P. nigra cv Italica cultivated in different sites of Santa Cruz. Laboratory decay tests were carried out using the modified ASTM Standards D-1413 (1976) and the López and Deschamps (1978) technique, with two fungal species: white rot Trametes versicolor and brown rot Lentinus lepideus . Lenga ( Nothofagus pumilio ) heartwood, a widely used native timber in the region, was also included in the study as a control. Physical and anatomical analyses were carried out. Although important differences were found in anatomical and physical properties of Alamo timbers between sites of, no significant differences were found in relative weight loss over 50 and 150 days, for either fungal species. Natural Alamo timber had the greatest weight loss over 150 days (66.8% for T. versicolor and 29.8% for L. lepideus ). CCA treatment improved the Alamo wood durability compared with Lenga heartwood (1.1% versus 29.2% weight loss with T . versicolor and 2.5% versus 13.6% for L. lepideus , respectively).

Effect of the antifungal activity of oxygenated aromatic essential oil compounds on the white-rot Trametes versicolor and the brown-rot Coniophora puteana

Essential oils and their constituents have a long history of applications as antimicrobial agents, but their use as wood preservatives has not yet been reported. In this study, 22 essential oil phenols, phenol ethers, and aromatic aldehydes have been tested for their antifungal activity against the wood-decaying fungi Trametes versicolor and Coniophora puteana . Minimal inhibitory concentrations of the selected compounds added to potato dextrose agar (PDA) in defined concentrations were determined by a screening test with the agar dilution method. A significant difference in the tolerance of the tested fungi towards the selected compounds was discovered and attributed to the differences in their metabolic characteristics. The influence of the chemical structure of the tested essential oil compounds on their antifungal activity is also discussed.