Gloeophyllum Trabeum Research Articles

Effect of exterior wood coatings on the durability of cross-laminated timber against mold and decay fungi

Cross-laminated timber (CLT) is increasingly used in building construction worldwide. Durability of CLT against fungal attack has yet to be fully explored. Water intrusion in mass timber can yield dimensional changes and microbial growth. This study evaluated the performance of CLT coated with various water- and solvent-based stains commercially available in the United States. Twelve coatings were tested for moisture excluding effectiveness, water repellency effectiveness, volumetric swelling, and anti-swelling efficiency. Only five coatings repelled water, limiting dimensional changes. A modified version of AWPA E10-16 (2016) was performed to evaluate decay of the coated CLT samples. Weight losses were recorded after 18 weeks’ exposure to the brown-rot decay fungus Gloeophyllum trabeum. In accelerated mold testing, coated CLT samples were grown in chambers containing spores of Aspergillus sp., Rhizopus sp., and Penicillium sp. for 29 d and assessed visually for mold growth. In both tests, coating C (transparent, water-based, alkyd/acrylic resin) performed the best among the tested coatings. Mold growth was completely prevented, and weight loss caused by G. trabeum was approximately 1.33%. Although coating C prevented decay for 18 weeks, coatings are not intended to protect against decay fungi. However, they may offer short-term protection during transport, storage, and construction.

Design and synthesis of new benzofuran-1,2,3-triazole hybrid preservatives and the evaluation of their antifungal potential against white and brown-rot fungi

A series of novel benzofuran-1,2,3-triazole hybrids were synthesized and investigated as fungicidal preservatives. The compounds were evaluated for their antifungal potential against white-rot (Trametes versicolor), dry brown-rot (Poria placenta), and wet brown-rot (Coniophora puteana and Gloeophyllum trabeum) fungi, at different concentrations (500 ppm and 1000 ppm). The tests of the final products (8a, 8b, 8c, 8d, 8e, 8f, and 8g) demonstrated that compound N-((1-(4-fluorobenzyl)-1H-1,2,3-triazol-4-yl)methyl)benzofuran-2-carboxamide (8f) at a concentration of 500 ppm was the most active against wet brown-rot C. puteana (23.86% inhibition) and G. trabeum (47.16% inhibition) fungi. However, testing demonstrated that compounds 8a, 8b, 8c, 8d, and 8g at a concentration of 500 ppm did not exhibit acceptable antifungal effects against white-rot T. versicolor and dry brown-rot P. placenta fungi.

Assessment of volatile metabolites for in situ detection of fungal decay in wooden structures

Although incipient fungal decay of wood may be difficult to detect in early stages, it causes a significant decrease in wood strength. Developing a reliable non-destructive identification method of decay to overcome wood replacement costs is necessary. This study examined mass losses and compression strength decrease of a softwood, spruce pine (Pinus glabra), and a hardwood, quaking aspen (Populus tremuloides), exposed to two brown rot (Gloeophyllum trabeum and Postia placenta) and two white rot (Trametes versicolor and Irpex lacteus) fungi, and identified fungal volatile organic compounds (VOCs) collected over 12 weeks of decay. Principal component analysis (PCA) of VOCs spectra differentiated volatiles emitted from sound wood and wood exposed to fungi. Volatile compounds from two fungal species revealed distinctive patterns of early and late decay stages in each wood species. The overall distinct volatile patterns of fungal decay showed promising results for development of non-destructive identification of incipient decay in wooden building structures.

Functional Genomics, Transcriptomics, and Proteomics Reveal Distinct Combat Strategies Between Lineages of Wood-Degrading Fungi With Redundant Wood Decay Mechanisms.

Wood-degrading fungi vary in their strategies for deconstructing wood, and their competitive successes shape the rate and fate of carbon released from wood, Earth’s largest pool of aboveground terrestrial carbon. In this study, one-on-one interspecific interactions between two model brown rot (carbohydrate-selective) fungi, Gloeophyllum trabeum and Rhodonia (Postia) placenta, were studied on wood wafers where a clearly resolved interaction zone (IZ) could be generated, reproducibly. Comparative RNAseq and proteomics between the IZ and non-interacting hyphae of each species identified combative strategies for each fungus. Glycoside hydrolases were a relatively smaller portion of the interaction secretome compared to non-interacting hyphae. The interaction zone showed higher pectinase specific activity than all other sampling locations, and higher laminarinase specific activity (branched β-glucan proxy) was seen in the IZ secretome relative to equivalent hyphae in single-species cultures. Our efforts also identified two distinct competitive strategies in these two fungi with a shared nutritional mode (brown rot) but polyphyletic ancestral lineages. Gloeophyllum trabeum (Gloeophyllum clade) upregulated more secondary metabolite (SM) synthesis genes in response to a competitor than did R. placenta. R. placenta (Antrodia clade) upregulated a larger variety of uncharacterized oxidoreductases in interacting hyphae, suggesting that these may play a role in mediating competitor response in this fungus. Both species produced several hypothetical proteins exclusively in the interaction zone, leaving questions as to the function of these proteins. This work supports the existence of multiple interaction strategies among brown rot fungi and highlights the functional diversity among wood decay fungi.

Innovation in Wood Preservation.

The wood preservation industry has depended on toxicity as a mechanism of effectiveness against decay fungi to extend the life of wood used in adverse conditions. An alternative to toxicity, however, is to study and understand the mechanism of fungal attack and stop it before it can start. Knowing that fungi need moisture for colonization, a new approach to wood preservation is to lower the cell wall moisture content below that needed for fungal attack. Acetylation chemistry is known to reduce the moisture content in the cell wall, and it was used to study moisture levels in the bulk cell wall and in the isolated cell wall polymers. Resistance to brown-rot was determined using a 12-week soil block test with Gloeophyllum trabeum. Weight loss was measured and an analysis of what was lost was determined.

Chemical characterization and biological resistance of thermally treated bamboo

The aim of this study was to evaluate the chemical characteristics and biological resistance of thermally treated bamboo to decay fungi and xylophagous termites. Four stalks were collected in adulthood and cut every 2.10 m, divided into 50 cm parts, and then divided into four sections (slats) in the longitudinal direction. The slats were immersed in water for 10 days and air seasoned. The slats were processed into laminas with dimensions of 0.5 × 3.5 × 45 cm (thickness × width × length) and thermally treated at 140, 160, 180 and 200 °C for one hour at each temperature and compared those oven dry to 100 °C (control). Chemical analysis and testing of natural resistance involved the random collection of samples of thermally treated laminas and control with dimensions of 0.5 × 2.0 × 2.0 cm (thickness × width × length), which were classified by temperature. Bamboo decay resistance was tested with two brown rot fungi (Postia placenta and Gloeophyllum trabeum) and one species of subterranean termite (Nasutitermes corniger). The concentrations of extractives and total lignin increased with increasing temperature, and the holocellulose content was reduced. This may decrease the mechanical strength of bamboo and bamboo composites; but on the other hand, will increase your resistance to decay when exposed to more severe environmental conditions. Ultimately, there was a gain in natural resistance from temperature treatments of 140 °C to the tested fungi. To the termite, the heat treatments not provided improvement in biological resistance of the bamboo.

Variation in the chemical composition of Amazonian woods submitted to decay fungi

As a biological material, wood is susceptible to the action of xylophagous agents, which alter its physical and chemical properties, with the decay fungi standing out among these, causing damage and changing the chemical composition of the wood, as a result of the metabolism of its components. This study evaluated changes of the main chemical components of four Amazonian wood species after the attack of two decay fungi by means of gravimetric chemical analysis and mid-infrared spectroscopy. The chemical analyzes allowed distinguishing the action mechanisms of the fungi in relation to the chemical components of the wood. Overall, after the action of the Gloeophyllum trabeum fungus (brown rot), a reduction in the holocellulose proportion was observed, while for Trametes versicolor (white rot) it was a reduction of lignin. With the principal component analysis (PCA) results, it was possible to separate the treatments per wood, by using its mass loss and chemical components. It was also possible to differentiate the decay fungi by using the absorbance band intensities of the mid-infrared spectrum. As a conclusion, the mid-infrared spectroscopy has proved to be a useful tool in distinguishing classes of decay fungi. Further researches on this may contribute to create a more robust database for the identification of decay fungi action in wood.

Nanostructural Analysis of Enzymatic and Non-enzymatic Brown Rot Fungal Deconstruction of the Lignocellulose Cell Wall†.

Brown rot (BR) decay mechanisms employ carbohydrate-active enzymes (CAZymes) as well as a unique non-enzymatic chelator-mediated Fenton (CMF) chemistry to deconstruct lignocellulosic materials. Unlike white rot fungi, BR fungi lack peroxidases for lignin deconstruction, and also lack some endoglucanase/cellobiohydrolase activities. The role that the CMF mechanism plays in “opening up” the wood cell wall structure in advance of enzymatic action, and any interaction between CMF constituents and the selective CAZyme suite that BRs possess, is still unclear. Expression patterns for CMF redox metabolites and lytic polysaccharide monooxygenase (LPMO–AA9 family) genes showed that some LPMO isozymes were upregulated with genes associated with CMF at early stages of brown rot by Gloeophyllum trabeum. In the structural studies, wood decayed by the G. trabeum was compared to CMF-treated wood, or CMF-treated wood followed by treatment with either the early-upregulated LPMO or a commercial CAZyme cocktail. Structural modification of decayed/treated wood was characterized using small angle neutron scattering. CMF treatment produced neutron scattering patterns similar to that of the BR decay indicating that both systems enlarged the nanopore structure of wood cell walls to permit enzyme access. Enzymatic deconstruction of cellulose or lignin in raw wood samples was not achieved via CAZyme cocktail or LPMO enzyme action alone. CMF treatment resulted in depolymerization of crystalline cellulose as attack progressed from the outer regions of individual crystallites. Multiple pulses of CMF treatment on raw wood showed a progressive increase in the spacing between the cellulose elementary fibrils (EFs), indicating the CMF eroded the matrix outside the EF bundles, leading to less tightly packed EFs. Peracetic acid delignification treatment enhanced subsequent CMF treatment effects, and allowed both enzyme systems to further increase spacing of the EFs. Moreover, even after a single pulse of CMF treatment, both enzymes were apparently able to penetrate the cell wall to further increase EF spacing. The data suggest the potential for the early-upregulated LPMO enzyme to work in association with CMF chemistry, suggesting that G. trabeum may have adopted mechanisms to integrate non-enzymatic and enzymatic chemistries together during early stages of brown rot decay.

Antifungal activity and fire resistance properties of nano-chitosan treated wood

Fungal decay and fire resistance properties of wood treated with nano-chitosan-TPP particles were investigated. Quaternized and non-quaternized nano-chitosan particles crosslinked with a commercial fire-retardant, tripolyphosphate, were prepared from low molecular weight chitosan (with a molecular weight of 50 to 190 kDa). Different treatments were performed on southern yellow pine wood samples via a vacuum impregnation process for both quaternized and non-quaternized nano-chitosan-TPP particles with a concentration ratio of 12% to 4.8% (nano-chitosan to TPP). Both the leached and unleached treated wood samples were exposed to brown rot (Gloeophyllum trabeum) and white rot (Trametes versicolor) fungi according to AWPA standard E10-16. The flammability test was performed with a cone calorimeter according to ASTM standard E1354-15. The heat release rate and the mass loss rate were measured. The results of the fungal tests indicated that the quaternization of the nano-chitosan particles resulted in a reduced mass loss in the pine samples when exposed to Trametes versicolor under leached conditions. Additionally, without the quaternization of the nano-chitosan particles, the mass loss in the pine samples was reduced when exposed to Gloeophyllum trabeum under unleached conditions. The production of nano-chitosan-TPP particles had a significant effect on the fire-retardant activity of the treated wood samples.

Revalorization of coffee silverskin as a potential feedstock for antifungal chemicals in wood preservation

The possibility of using coffee silverskin, an industrial waste from the coffee roasting process, as an antifungal feedstock in wood preservative formulations was investigated. Silverskin hot water extract and its antifungal properties in vitro against Rhodonia (Poria) placenta, Gloeophyllum trabeum, and Trametes versicolor were characterized, and its in vitro effects on wood decay caused by Coniophora puteana were analyzed. A kinetic luminescent bacteria test was performed using Aliivibrio fischeri to measure the acute ecotoxicity of the silverskin extracts. The antifungal test showed 60–70% growth inhibition of the studied fungi at higher concentrations—3%—but did not meet the high inhibition—100%—of the commercial wood preservative. The phenolic compounds, such as chlorogenic acid and its derivatives, and caffeine derivatives, were the main constituents of the silverskin extracts and considered the responsible compounds of the fungal inhibition. The silverskin extracts were significantly less toxic than the commercial copper-based wood preservative. Revalorization of silverskin from industrial residues does not perform as a wood preservative but it remains a potential source of antifungal chemicals for wood preservative formulations.

Daños químico-mecánicos causados por el hongo de pudrición café Gloeophyllum trabeum (Pers.) Murrill en madera de Pinus pseudostrobus Lindl.

Introduction: Wood is susceptible to be used as a carbon source by fungal species damaging the wood. Its durability has been categorized according to its weight loss, without taking into account the decrease in the inherent physicochemical and mechanical properties. Objective: To evaluate how how weight loss affects the physicochemical and mechanical properties of Pinus pseudostrobus Lindl. wood exposed to brown-rot fungi Gloeophyllum trabeum (Pers.) Murrill. Materials and methods: Sawn timber pieces of P. pseudostrobus were inoculated with 50 mL of G. trabeum (106 UFC∙mL-1). Periodically (zero, three, six and nine months) and with the help of a universal testing machine, parallel compression (PC), static bending (SB) and perpendicular compression to the grain (CPG) were evaluated, and holocellulose, cellulose and lignin were quantified. Results and discussion: After nine months of interaction with G. trabeum, the pieces of wood were resistant to degradation, taking into account only weight loss. However, the chemical-mechanical properties evaluated showed that the fungus produced thinning and rupture of the tissue cells causing significant decrease in SB (100 to 56 N∙mm-2) and CPG (42.2 to 20.2 N∙mm-2), which reduced its resistance to mechanical stress. Conclusions: Wood exposed to fungal degradation is significantly affected in its mechanical properties, disqualifying it for construction. The damage is not reflected in the aesthetics of the material, which is surprising, since the common user of pine wood would not be able to notice the problem.

Anti-wood-fungal performance of methanol extracts of Rhizophora apiculata and R. mucronata barks

Various plant parts of Rhizophora species have been used in the treatment of a variety of diseases and illnesses. However, they have not been tested for antifungal properties related to wood decay fungi, especially the bark extractives. This study examined the methanol (MeOH) crude extracts of R. apiculata and R. mucronata barks in terms of the amount of extracts obtained and their antifungal properties. The antifungal activities of the crude MeOH extracts of both species were determined using the agar dilution method. Methanol crude extract from R. apiculata and R. mucronata were 10.8% and 15.7%, respectively and were toxic to Chaetomium globosum and Gloeophyllum trabeum at the concentration of 50 mg/mL.

β-Cyclodextrin-allyl isothiocyanate complex as a natural preservative for strand-based wood composites

Environmental concerns over chemicals used for protecting wood and wood products from biological degradation have prompted the development of natural wood preservatives with lower health risks and prolonged efficacy. In this study, an effective and environmentally friendly method is demonstrated to substantially improve the durability of a strand-based wood composite product by incorporating a natural wood preservative system. Specifically, allyl isothiocyanate (AITC), a mustard oil-based natural biocide, was encapsulated into the cavity of β-cyclodextrin (βCD) and the as-prepared βCD-AITC complex was applied in the strand-based composite manufacturing process to produce a natural-preservative-treated engineered wood panel. The formation of the βCD-AITC complex was qualitatively confirmed by attenuated total reflection-Fourier transform infrared spectroscopy, and the inclusion yield of AITC was estimated to be 71% by thermogravimetric analysis. The preservative complex was blended with southern pine strands at 0%, 5%, and 10% prior to the application of polymeric methylene diphenyl diisocyanate resin and hot-pressing. The application of the preservative system significantly improved decay resistance against brown-rot fungi, Gloeophyllum trabeum and Postia placenta, by keeping the average mass losses of the treated panels below 7%. The internal bond strengths of the treated panels were maintained above the required level for structural OSB for use in humid conditions specified in the European OSB product standard. This study suggests the βCD-AITC complex to be a promising alternative to conventional preservatives for the protection of wood composite products.

Qualidade e eficiência de produtos naturais no tratamento preservativo das madeiras de Araucaria angustifolia, Eucalyptus viminalis e Pinus taeda

A madeira, devido sua constituição orgânica, é altamente suscetível a agentes biodeterioradores, tornando-se essencial o tratamento preservativo àquelas que apresentam baixa durabilidade natural. Atualmente, os principais produtos utilizados no tratamento preservativo da madeira são o CCA e o CCB, os quais em razão da sua constituição são tóxicos ao meio ambiente e a saúde humana. Frente à essa situação, torna-se essencial o desenvolvimento de estudos acerca de produtos naturais que apresentem ação biocida, podendo assim ser utilizado no tratamento de madeira, conferindo maior proteção e aumentando a vida útil da peça. Levando em consideração esta perspectiva, o presente estudo teve por objetivo avaliar a qualidade (penetração e retenção) e eficiência de preservantes naturais aplicados no tratamento das madeiras de Araucaria angustifolia, Eucalyptus viminalis e Pinus taeda, submetidas ao apodrecimento acelerado em condições de laboratório. As madeiras das três espécies foram submetidas ao tratamento preservante com tanino, tall oil e óleo de nim, utilizando o método de imersão rápida a frio, na concentração de 5% do produto preservante, por cinco minutos. Na sequência foram avaliadas através do ensaio de apodrecimento acelerado sob à ação dos fungos apodrecedores Trametes versicolor e Gloeophyllum trabeum, seguindo as recomendações das normas ASTM D 2017 (2005) e ASTM D 1413 (1999). Com base nos resultados, observou-se que a madeira de P. taeda exibiu a melhor penetração aos preservantes óleo de nim e tall oil. O tanino retratou penetração vascular para as três espécies. Os melhores valores de retenção foram das madeiras de A. angustifolia e P. taeda, para todos os tratamentos aplicados. Quanto a eficiência, em comparação aos resultados encontrados para as outras espécies, todos os tratamentos foram eficientes para a madeira de P. taeda quando em contato ao fungo de podridão parda (G. trabeum).

Synthesis and Antimicrobial Activity of Metal-Containing Linseed Oil-Based Waterborne Urethane Oil Wood Coatings

In this study, the antimicrobial agents of mono(hydroxyethoxyethyl)phthalate (M(HEEP)2) with different metal of M = Zn, Mn, Pb, and Ca were synthesized from diethylene glycol (DEG), phthalic anhydride (PA), and divalent metal acetates including calcium acetate, zinc acetate, manganese acetate, and lead acetate, respectively. The waterborne urethane oil (WUO) dispersions synthesized from linseed oil, diisocyanates (hexamethylene diisocyanate (HDI) and isophorone diisocyanate (IPDI)), dimethylolpropionic acid at NCO/OH molars of 0.9, by acetone processing method were described as in our previous report. The M(HEEP)2 antimicrobial agents as well as the commercial nanosilver powder were added into WUO dispersions as the antimicrobial coatings. The effects of various antimicrobial agents and dosages (0.0, 0.2, 0.6, 0.8, 1.0, 2.0, and 4.0 phr) on antimicrobial activity of WUO films against gram-negative bacterium of Escherichia coli, gram-positive bacterium of Staphylococcus aureus, brown-rot fungus of Gloeophyllum trabeum, and white-rot fungus of Lenzites betulina were assessed. In addition, the film properties of the best antimicrobial WUO coatings were also examined. The results showed that the antimicrobial agents of mono(hydroxyethoxyethyl) phthalate M(HEEP)2 (M = Zn, Mn, Pb, and Ca) powders should certainly be synthesized by FTIR, 1H-NMR, 13C-NMR, and energy-dispersive X-ray spectroscopy (EDS) identifications and the yields of them were 43–55%. The results also revealed that the WUO film synthesizing with HDI films containing Zn(HEEP)2 of 2.0 phr and Pb(HEEP)2 of 0.4 phr had the best antibacterial activity for E. coli and S. aureus, respectively. The IPDI films containing Zn(HEEP)2 of 1.0 phr had the best antibacterial activity for both E. coli and S. aureus. For antifungal activity, the WUO film synthesizing with HDI films containing Pb(HEEP)2 of 0.8 phr and Zn(HEEP)2 of 2.0 phr as well as IPDI films containing Mn(HEEP)2 of 0.2 phr and Zn(HEEP)2 of 4.0 phr had the best performances against G. trabeum and L. betulina, respectively. Comparing with commercial nanoAg powder, the Zn(HEEP)2 and Pb(HEEP)2 had a superior antifungal efficiency for G. trabeum and L. betulina, while it had a slightly inferior efficiency in the antibacterial activity for E. coli and S. aureus. On the properties of WUO films, adding metal-containing antimicrobial agents could slightly enhance the thermal stability, but lowered the gloss of all films, however, the Tg value increased for HDI film and decreased for IPDI film. In addition to this, they had no significant difference in the film properties including hardness, impact resistance, bending resistance, adhesion, mass retention, and light-fastness between the WUO films with and without adding antimicrobial agents.

Antifungal ability and decay resistance of Fokienia hodginsii heartwood extract and its inhibitory effect on Gloeophyllum trabeum

The inhibitory ability of Fokienia hodginsii heartwood (FHH) extracts on Trametes versicolor (TV) and Gloeophyllum trabeum (GT) as well as the toxic effect of its heartwood extracts on GT were studied. The growth inhibition ability of the samples was analyzed using the growth rate method. The results showed that in the experiment of inhibiting TV, extracts using hot water had little effect, acetone extracts had the best inhibiting effect, and the lowest value of acetone EC50 was 0.409 g/L. The parameter EC50 is the concentration of the corresponding agent that inhibits the growth of 50% fungi. In the antifungal experiment of GT, methanol extract had the best inhibition effect, and the lowest EC50 value was 0.283 g/L. The antifungal effect of five solvent extracts of FHH was good when the concentration was 10% (w/w), and at this time, the mass loss rate of the test pieces was below 11%, all of them were Class I, indicating a strong antifungal level. After observing the samples of GT with SEM, it was found that the structure of methanol extract treatment was more complete and the antiseptic effect was better than that of the hot water extract treatment.

Bio-based Preservative using Methyl-β-cyclodextrin-Essential Oil Complexes for Wood Protection

Developing natural preservatives for wood protection is of great interest in sustainable construction and green building industries. This study was designed to determine the feasibility of using methyl-β-cyclodextrin-essential oils (MβCD-EOs) complexes as potential bio-based preservatives for wood protection. Four essential oils (EOs) with proven antifungal properties, eugenol (EG), trans-cinnamaldehyde (CN), thymol (TM) and carvacrol (CV), were complexed with methyl-β-cyclodextrin (MβCD) by a co-precipitation method. The inclusion of EOs in MβCD and the corresponding inclusion yield of the MβCD-EOs complexes were determined by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and ultraviolet-visible spectroscopy (UV/Vis), respectively. The maximum inclusion yields in MβCD-EG, MβCD-CN, MβCD-CV, and MβCD-TM were estimated to be almost 100%. MβCD-EOs complexes were impregnated into southern pine wood blocks and exposed to two brown rot fungi, Gloeophyllum trabeum and Postia placenta, following procedures described in AWPA Standard E22 and E10. The penetration of MβCD-EOs complexes in wood was confirmed by fluorescence microscopic analysis after the selective dyeing of EOs encapsulated in MβCD. In comparison to the control wood samples, MβCD-EOs complexes treated wood exhibited a significant reduction in the mass loss from 16–36% to 2–18%, accompanied by improvement in radial compression strength loss from 81–92% to 29–67% after four-week fungi exposure.

Biodegradation inducers to enhance wheat straw pretreatment by Gloeophyllum trabeum to second-generation ethanol production.

The native state of lignocellulosic biomass is highly resistant to enzymatic hydrolysis and the fermentation process of biofuel production. Brown-rot fungi use an extracellular Fenton system to degrade lignocellulosic biomass in the initial stages of decay. In this work, the combined effects of Mn2+, Fe2+, and NO3- inducers were evaluated based on the activities of hydrolytic enzymes and Fe3+ reduction as well as the catechol-type compound production during wheat straw pretreatment by the brown-rot fungus Gloeophyllum trabeum. Weight loss and chemical changes were evaluated to establish the culture conditions for stimulating wheat straw degradation using a central composite design. The results showed that weight loss and the Fe3+-reducing activity were promoted at the highest concentrations of Fe2+. A positive effect on catechol compound production by the addition of Mn2+ and NO3- was observed. Cellulase activity was increased at the highest concentration of NO3-. The multiple optimizations of G. trabeum culture conditions in wheat straw resulted in 11.3% weight loss and 0.47 total crystallinity index at 0.24M NO3-, 0.95mM Fe2+, and 0.85mM Mn2+ after 40days. The wheat straw pretreatment by G. trabeum for 10days increased glucose recovery. The results indicated that the wheat straw pretreatment using G. trabeum with biodegradation inducers could be a complementary step to physicochemical pretreatment of lignocellulosic biomass for production of second-generation ethanol.

A METHOD FOR EVALUATING ERGOSTEROL CONTENT IN WOOD-DECAY FUNGI

ABSTRACT Ergosterol is responsible for important functions in the fungal plasma membrane. The influence of fungitoxic agents on membrane ergosterol content is one of the most important mechanisms of antifungal action and its knowledge allows the generation of products that associate active compounds of different mechanisms, consequently improving the effectiveness of wood preservatives. Therefore, this study optimized a method for quantifying ergosterol in wood-decay fungi. The white-rot species selected were Ganoderma applanatum and Trametes versicolor, while the brown-rot were Gloeophyllum trabeum and Lentinus lepideus. Mycelial discs of each species were transferred to Petri dishes containing a cellophane-covered potato-dextrose-agar medium. Mycelia of each fungus were collected, weighed, and transferred to test tubes with 5 mL of 25% alcoholic potassium hydroxide. The tubes were vortexed for 5 min, subjected to ultrasound for 5 min, incubated at 85 °C for 4 h, followed by the addition of 2 mL of sterile distilled water and 5 mL of n-heptane and subsequent ultrasound shaking for 2 min. The n-heptane layer was analyzed by UV spectrophotometry between 230 and 300 ηm. The blank sample only contained n-heptane. The mycelia wet weight of the fungi ranged from 0.061 to 0.296 g. Ergosterol content was 0.007% for Lentinus lepideus and 0.004% for the other species. The absorbance was higher than the ones observed in the blank for all samples. The adapted method was efficient for ergosterol extraction.

Effect of Multiple Leaching Cycles on Decay Resistance of Micronized Copper Azole–Treated Southern Pine Sapwood

Abstract Copper remains one of the key biocides for protecting timber in soil contact. Historically, copper-based preservatives relied on solubilized copper. Over the past decade, micronized copper systems have largely replaced soluble copper systems in this application. While micronized copper chemistries have been shown to perform well over time with reduced copper leaching compared to solubilized copper, data are lacking on the effects of repeated leaching cycles on resistance of the timber to fungal attack. The potential effects of repeated leaching cycles of micronized copper azole–treated southern pine (Pinus spp.) blocks on both copper losses and resistance to fungal attack were explored over 20 leaching cycles using Gloeophyllum trabeum and Rhodonia placenta as test fungi. Copper losses during leaching were elevated for the first two cycles and steadily declined with additional cycling. There were no noticeable differences in fungal-associated weight losses in blocks exposed to G. trabeum. There was only a slight increase in average block weight losses with R. placenta, although blocks exposed to this fungus experienced higher weight losses with increased leaching cycles. The results suggest that repeated leaching exposures may produce some localized increases in susceptibility to fungal attack, but the overall effects were minor.