The Protection of Beech Wood (”Fagus Sylvatic”a) against the brown Rot ”Postia Placenta” using Clove (”Eugenia Caryophyllata”) Essential Oil in a Linseed Oil Medium

The present research investigates the antifungal efficiency of clove (Eugenia caryophyllata) essential oil (C-EO) combined with linseed oil (LO) at different concentrations (1%, 5%, 10%) using two types of mycological tests: a qualitative screening test by agar diffusion method and a quantitative mini-block test on treated beech (Fagus sylvatica) wood.The agar diffusion test indicated improved protection of wood should be possible with a mixture of C-EO and LO from a concentration of 5%. In contrast, the mini-block test indicated that wood is partially protect by LO alone and that adding increasing quantities of C-EO gradually reduces this protection.One possible explanation of this unexpected result could be the antioxidant effect of C-EO which could negatively interfere in the oxidative curing process of LO. ESEM investigation revealed the penetration of LO and C-EO/LO mixtures into the wood structure and non-uniform fungal colonization of all the samples exposed to Postia placenta, as well as some characteristic features of consequent wood structure degradation, which was found more advanced for the untreated beech wood samples.

Efecto de pudrición por hongos en las propiedades físicas y mecánicas del compuesto bambú-polipropileno

Se evaluó la resistencia a la biodegradación de un material compuesto bambú-polipropileno, mediante la exposición a dos hongos: Pycnoporus sanguineus de pudrición blanca, utilizado en ensayos de durabilidad natural y Rhodonia placenta (sinónimo: Postia placenta) de pudrición café durante 16 semanas, según la norma ASTM D2017-05. Asimismo, se evaluó el efecto de la biodegradación en las propiedades físicas de densidad, absorción e hinchamiento; y las mecánicas de flexión, tracción e impacto. El material compuesto se elaboró por extrusión y posterior moldeo por compresión; para ello se utilizaron partículas de bambú (Guadua angustifolia) de dos tamaños de malla ASTM: 40/60 y 60/80; dos proporciones bambú/polipropileno: 30/70 y 50/50; además de 2 % de anhídrido maleíco de polipropileno (MAPP), como agente acoplante. Se demostró que el compuesto bambú-polipropileno fue susceptible a la biodegradación por hongos de pudrición blanca y café; la formulación con menor proporción de partículas de bambú (30 %) presentó mayor resistencia a la biodegradación. Las propiedades físicas de densidad anhidra, absorción e hinchamiento y las propiedades mecánicas de flexión estática y tracción fueron afectadas de manera inversa a causa de la exposición a P. sanguineus y R. placenta. Los hongos de pudrición blanca y café no incidieron en la propiedad de impacto.

Natural durability and chemical composition of the Liquidambar sp. wood

The wood is a material of biological origin and because of its chemical composition is subject to the attack of various organisms that use it as a source of food. Thus, this study aimed to evaluate the natural durability and chemical composition of the Liquidambar sp. wood. Were performed the accelerated laboratory test, with a pure culture of the Postia placenta fungus, causer of brown rot , and no choice-feeding of termites Nasutitermes corniger. After both tests, the samples were dried in an oven at 103 ± 2ºC until reaching constant mass and later weighed, to evaluate the percentage of mass loss. The contents of extractives, soluble, insoluble and total lignin, and holocellulose were also determined. The studied wood obtained losses of mass of 37.79% and 23.37%, when submitted to the action of fungus and termites, respectively, and an average extractive content equal to 4.13%. It is concluded that the Liquidambar sp. wood was moderate resistance to the attack of the brown rot fungus, and little resistant to the action of employed termites.

Wood Modification by Furfuryl Alcohol Resulted in a Delayed Decomposition Response in Rhodonia (Postia) placenta

ABSTRACT The aim of this study was to investigate differential expression profiles of the brown rot fungus Rhodonia placenta (previously Postia placenta) harvested at several time points when grown on radiata pine (Pinus radiata) and radiata pine with three different levels of modification by furfuryl alcohol, an environmentally benign commercial wood protection system. The entire gene expression pattern of a decay fungus was followed in untreated and modified wood from initial to advanced stages of decay. The results support the current model of a two-step decay mechanism, with the expression of genes related to initial oxidative depolymerization, followed by an accumulation of transcripts of genes related to the hydrolysis of cell wall polysaccharides. When the wood decay process is finished, the fungus goes into starvation mode after five weeks when grown on unmodified radiata pine wood. The pattern of repression of oxidative processes and oxalic acid synthesis found in radiata pine at later stages of decay is not mirrored for the high-furfurylation treatment. The high treatment level provided a more unpredictable expression pattern throughout the incubation period. Furfurylation does not seem to directly influence the expression of core plant cell wall-hydrolyzing enzymes, as a delayed and prolonged, but similar, pattern was observed in the radiata pine and the modified experiments. This indicates that the fungus starts a common decay process in the modified wood but proceeds at a slower pace as access to the plant cell wall polysaccharides is restricted. This is further supported by the downregulation of hydrolytic enzymes for the high treatment level at the last harvest point (mass loss, 14%). Moreover, the mass loss does not increase during the last weeks. Collectively, this indicates a potential threshold for lower mass loss for the high-furfurylation treatment. IMPORTANCE Fungi are important decomposers of woody biomass in natural habitats. Investigation of the mechanisms employed by decay fungi in their attempt to degrade wood is important for both the basic scientific understanding of ecology and carbon cycling in nature and for applied uses of woody materials. For wooden building materials, long service life and carbon storage are essential, but decay fungi are responsible for massive losses of wood in service. Thus, the optimization of durable wood products for the future is of major importance. In this study, we have investigated the fungal genetic response to furfurylated wood, a commercial environmentally benign wood modification approach that improves the service life of wood in outdoor applications. Our results show that there is a delayed wood decay by the fungus as a response to furfurylated wood, and new knowledge about the mechanisms behind the delay is provided.

Mechanical properties and resistance to fungi and termite in particleboard of eucalyptus

The objective of this study was to evaluate the mechanical resistance and resistance to degrading agents in particleboard with eucalyptus wood residue and Urea-Formaldehyde, Phenol-Formaldehyde and Tannin-Formaldehyde adhesives at two temperatures (120 ºC and 140 ºC). The panels were produced in the dimensions of 40 cm × 40 cm × 1.25 cm (width, length and thickness, respectively); 10% and 20% of tannin (50% solution) was added to the pure adhesives. The following parameters were evaluated: Modulus of Rupture (MOR) and Modulus of Elasticity (MOE) in static bending, internal bonding, screw withdrawal, resistance to rotting fungi and dry wood termite. MOR showed better results at 120 °C. None of the treatments reached the minimum standard for the MOE, contrary to the internal bonding. The Trametes versicolor fungus caused greater mass loss to the tested panels when compared to Postia placenta. The proportion of tannin (90:10) in the phenolic adhesive contributed to a decrease in the resistance of the panel to the dry wood termite.

Wood modification by furfuryl alcohol caused delayed decomposition response inRhodonia (Postia) placenta

ABSTRACTThe aim of this study was to investigate differential expression profiles of the brown rot fungusRhodonia placenta(previouslyPostia placenta) harvested at several time points when grown onPinus radiata(radiata pine) andP. radiatawith three different levels of modification by furfuryl alcohol, an environmentally benign commercial wood protection system. For the first time the entire gene expression pattern of a decay fungus is followed in untreated and modified wood from initial to advanced stages of decay. Results support the current model of a two-step decay mechanism, with an initial oxidative depolymerization followed by hydrolysis of cell-wall polysaccharides. The wood decay process is finished, and the fungus goes into starvation mode after five weeks when grown on unmodifiedP. radiatawood. The pattern of repression of oxidative processes and oxalate synthesis found inP. radiataat later stages of decay is not mirrored for the high furfurylation treatment. The high treatment level provided a more unpredictable expression pattern throughout the entire incubation period. Furfurylation does not seem to directly influence the expression of core plant cell wall hydrolyzing enzymes, as a delayed and prolonged, but similar pattern was observed in theP. radiataand the modified experiments. This indicates that the fungus starts a common decay process in the modified wood, but proceeds at a slower pace as access to the plant cell wall polysaccharides is restricted. This is further supported by the downregulation of hydrolytic enzymes for the high treatment level at the last harvest point (mass loss 14%). Moreover, the mass loss does not increase the last weeks. Collectively, this indicates a potential threshold for lower mass loss for highly modified wood.IMPORTANCEFungi are important decomposers of woody biomass in natural habitats. Investigation of the mechanisms employed by decay fungi in their attempt to degrade wood is important for both the basic scientific understanding of ecology and carbon cycling in nature, and for applied uses of woody materials. For wooden building materials long service life and carbon storage is essential, but decay fungi are responsible for massive losses of wood in service. Thus, optimizing durable wood products for the future are of major importance. In this study we have investigated the fungal genetic response to furfurylated wood, a commercial environmentally benign wood modification approach, that improves service life of wood in outdoor applications. Our results show that there is a delayed wood decay by the fungus as a response to furfurylated wood and new knowledge about the mechanisms behind the delay is provided.

ANÁLISE FÍSICA E AVALIAÇÃO DO EFEITO ANTIFÚNGICO DOS ÓLEOS DE ANDIROBA, COPAÍBA E PINHÃO-MANSO

Óleos de andiroba, copaíba e pinhão-manso são estudados por serem empregados em fins variados, como sabões, velas, medicamentos, biodiesel, tintas, fiação de lã e lustração de móveis. Também, são utilizados como inseticidas, fungicidas e moluscicidas. Objetivou-se neste trabalho caracterizar as propriedades físicas dos óleos de andiroba, copaíba e pinhão-manso, puros ou enriquecidos com iodo sublimado (I2) e avaliar sua eficiência contra fungos de podridão parda e branca. Os óleos de andiroba e copaíba foram oriundos de comunidades do município de Santarém (PA) e o óleo de pinhão-manso, da Fazenda Tamanduá, município de Santa Terezinha (PB). Foram determinadas as características físicas (pH, índice de acidez, viscosidade e densidade) dos óleos e realizado o ensaio de toxidez em meio de cultura com fungos de podridão parda e branca. O enriquecimento dos óleos com iodo (I2) proporcionou aumento da viscosidade. Foi constatada menor densidade para o óleo puro de andiroba e copaíba do que para o enriquecido com 5% de I2. O incremento de iodo nas soluções propiciou a diminuição de pH nos óleos de andiroba e copaíba, além do aumento do índice de acidez do óleo de andiroba. Para a avaliação da eficiência, os óleos foram empregados puros ou enriquecidos com iodo sublimado. No ensaio de toxidez em meio de cultura, para o fungo Trametes versicolor, a maior inibição em 20 dias foi para o tratamento com andiroba 1% de I2. Para o fungo Postia placenta, a maior inibição foi constatada para o tratamento com óleo de andiroba com 5% de I2.