Biological Resistance to Xylophagous Organisms of Two Lesser-Known Timber Species from the Caatinga Biome

Abstract: This evaluated the natural resistance of wood from seven Eucalyptus trees in field decay and soil bed tests. Two 12-year-old trees were randomly sampled per species, with 2,2 m logs being obtained from the basal section of each tree. The samples were taken in two positions in the radial direction of the stem (middle heartwood and transition zone; containing heartwood and sapwood). The field decay tests were installed in three municipalities in the southern state of Espírito Santo, and the soil utilized soil from the three field decay test areas. The field decay tests were evaluated after six, 12 and 18 months after installation and the soil bed tests after six months. The Scott-Knott test (p ≤ 0,05) was used in the analysis and evaluation of the tests. The sapwood-heartwood (transition region) exhibited the greatest mass losses for the field decay and soil bed tests. On average, for the soil bed test the lowest mass losses were observed for the soil of Vargem Alta (5,00 %), with greater mass losses observed for São José do Calçado (7,05 %) and Jerônimo Monteiro (9,90 %). In the field decay test the organisms present in the soil of São José do Calçado and related to the organic matter content Eucalyptus grandis and Eucalyptus saligna more intensely.

Evaluation of wood preservatives in soil-contact tests is becoming an important issue since detoxification of wood-protecting compounds by fungi and bacteria found in soil may decrease the resistance of treated wood. In this study, the decay resistance of wood treated with didecyl dimethyl ammonium tetrafluoroborate (DBF), a recently developed quaternary ammonia compound, was evaluated in both soil bed and laboratory decay resistance tests. Small specimens (5×10×100 mm3) of DBF-treated and untreated sugi sapwood were subjected to decay in laboratory soil bed tests (DIN ENV 807 (2001)) followed by Basidiomycetes tests (DIN EN 113 (1996)). Exposure in field soil and compost soil substrates was used to observe the effects of wood degrading and other soil-inhabiting micro-organisms on the decay resistance of the specimens. Soil bed tests showed that DBF-treated wood specimens at 7.7 kg/m3 retention level (1% DBF solution concentration) showed better performance compared to 0.01 and 0.1% DBF treatments. The 7.7 kg/m3 retention level was also effective to protect the wood specimens against Coniophora puteana and Coriolus versicolor in Basidiomycetes tests. It is concluded that detoxification of wood preservatives in soil contact is an important factor to determine protective properties of treated wood in ground contact applications. Further experiments with larger specimens are needed to observe the performance of DBF-treated wood at higher retention levels in field above ground and ground contact tests.

We have conducted a genome-level comparative study of basidiomycetes wood-rotting fungi (white, brown and soft rot) to understand the total plant biomass (lignin, cellulose, hemicellulose and pectin) -degrading abilities. We have retrieved the genome-level annotations of well-known 14 white rot fungi, 15 brown rot fungi and 13 soft rot fungi. Based on the previous literature and the annotations obtained from CAZy (carbohydrate-active enzyme) database, we have separated the genome-wide CAZymes of the selected fungi into lignin-, cellulose-, hemicellulose- and pectin-degrading enzymes. Results obtained in our study reveal that white rot fungi, especially Pleurotus eryngii and Pleurotus ostreatus potentially possess high ligninolytic ability, and soft rot fungi, especially Botryosphaeria dothidea and Fusarium oxysporum sp., potentially possess high cellulolytic, hemicellulolytic and pectinolytic abilities. The total number of genes encoding for cytochrome P450 monooxygenases and metabolic processes were high in soft and white rot fungi. We have tentatively calculated the overall lignocellulolytic abilities among the selected wood-rotting fungi which suggests that white rot fungi possess higher lignin and soft rot fungi potentially possess higher cellulolytic, hemicellulolytic and pectinolytic abilities. This approach can be applied industrially to efficiently find lignocellulolytic and aromatic compound-degrading fungi based on their genomic abilities.

Aim of study: to assess the natural durability of Populus x euramericana ‘I-214’ against xylophagous fungi and termites, and to carry out a macro-microscopic analysis of the alterations caused by each xylophagous agent in order to get the necessary information for its possible inclusion in existing European standards.Area of study: A 20-years-old commercial plantation Populus x euramericana‘I-214’ located in Quintanilla de Sollamas (42° 36′ 00″N - 05° 49′ 00″ W), Spanish community of Castile-LeonMaterial and methods: material sampling and selection was carried out following EN 350:2017 for commercial sawn timber. Poplar resistance to xylophagous basidiomycete, soft rot fungi and subterranean termites was determined according to CEN/TS 15083-1:2005, CEN/TS 15083-2:2005 and EN 117:2012, respectively. The durability and use classes were estimated according to EN 350:2016 and EN 335:2013, respectively. The anatomical studies were carried out with Optical and Scanning Electron Microscope. Material characterization was carried out by reference to Anagnost (1998) and Schwarze (2007).Main results: ‘I-214’ poplar wood proved to be “Not-durable” to the action of basidiomycetes, soft rot fungi and termites, use classes 1-2, and showed macro-microscopic evidence of these types of decay.Research highlights: the information obtained in this study would allow the inclusion of clone I-214 in the standard EN 350 and its explicit classification within it.Keywords: wood-decay fungi; termites; EN 350.Abbreviations used: TM: test material; RM: reference material; RH: relative humidity; ML: mass loss; mi: initial dry mass; mf: final dry mass; DC: durability class; OM: Optical Microscope; SEM: Scanning Electron Microscope; TS: transverse section samples; LS: longitudinal section samples; CI: robust confidence intervals; F: fibre; V: vessel; h: hole; t: erosion trough; R: radial parenchyma cell; ep: erosion pitting; Fc: fungal colonization; fr: fracture; c: cavity; b: bore hole; m: mycelium.

Several soft and white rot fungi were compared in their ability to degrade specifically 14C-labelled phenols and dehydropolymers of labelled coniferyl alcohol. Furthermore, plant material, which was expected to be specifically labelled in the lignin part was used in the degradation studies. The experiments showed that both groups of fungi were able to release CO2 from methoxyl and carboxyl groups of phenol-carboxylic acids, to degrade side chains of cinnamic acids and cinnamyl alcohols and even to decompose aromatic structures. With the dehydropolymers and the plant material a CO2 release from the methoxyl groups, the side chains and the aromatic carbons was observed. The time dependant course of the CO2 release from these different groups showed in the beginning a higher CO2 evolution from the side chain carbons than from the methoxyl groups, which were later on released to a higher extent. No laccase activity could be detected in the soft rot fungi and the peroxidase activity was lower than in the white rot fungi.

Thermally modified wood has many technically interesting properties, such as increased dimensional stability, low equilibrium moisture content, and enhanced biological and weather resistance. This paper describes solid-state nuclear magnetic resonance (NMR) and Fourier transform infrared (FT-IR) spectroscopic studies on the decay of heat-treated and untreated pine (Pinus sylvestris) by brown (Poria placenta) and soft rot fungi. Both techniques combined with multivariate data analysis proved to be powerful tools for the study of wood degradation by fungi. When untreated pine was exposed to brown or soft rot fungi, a drastic decay of the cell wall polysaccharides was observed. Brown rot fungus degraded mainly hemicelluloses while soft rot fungus attacked cellulose more extensively. The aromatic region of 13C cross-polarization magic angle spinning (CPMAS) NMR spectra revealed that the structure of lignin was also altered. New carboxylic structures were formed as a consequence of the decay. The increased biological resistance of pine wood heat-treated at >220 degrees C was observed in the 13C CPMAS NMR and IR spectra.

Fungal deterioration of a novel scrimber composite made from industrially heat treated African highland bamboo

Assessment of the biocontrol potential of a Trichoderma viride isolate : Part II: Protection against soft rot and basidiomycete decay

Summary The objective of the study was to investigate whether soluble sugars and nitrogenous compounds in wood have an impact on susceptibility of wood to decay in ground contact, which is important in the field of test methodology and standardization. Kiln drying of Scots pine planks caused a distinct gradient of low-molecular weight (LMW) sugars and nitrogenous compounds in the 0–2 mm zone at the surface of the timber, whereas the deeper zones had constant and low contents of soluble substances. Strips, containing different content of soluble nutrients, were cut and exposed in two types of soil; the former one being rich in soft rot fungi, the latter one being rich in soft rot fungi and bacteria. The strips rich in nutrients showed an average of 16 % of mass loss whereas samples poorer in nutrients were less affected (8–9 %) after 120 days of exposure in the soil rich in soft rot fungi. A pure culture test with the soft rot fungus Phialophora mutabilis confirmed the above-mentioned observation. The result is in favour of taking samples with approximately equal content of soluble nutrients to decrease the variability of test results, e.g., mass losses. The garden compost, rich in both soft rot fungi and bacteria, caused severe mass loss (40–48 %) of the strips after 120 days of exposure. No difference in the mass losses of the samples was measured. The choice of test soil as well as the nutrient status of the samples can lead to completely different results and, consequently, conclusions.

The wood preservative potential of long-lasting Amazonian wood extracts

Jack fruit (Artocarpus heterophyllus) is most widely cultivated in Andhra Pradesh, india. It has high nutritional values, medicinal values, rich phytochemical compositions, minerals etc. Such crop plants are infected by soft rot causing fungi by Rhizopus artocarpi (Berk. & Broome) Boedijn, in Andhra pradesh, India. The flowers and fruits are severally damaged by soft rot fungi. So this soft rot fungus was isolated from fruits and identified as R. artocarpi (Berk. & Broome) Boedijn. The soft rot fungus is grown on PDA medium and cultural characters are studied. The antifungal test is done by using fungal extracts from Phelinus noxius and Ganoderma lucidum and leaf extract Prosopis juliflora (Sw.) DC. In early stage of infection, Rhizopus spores deposit on moist fruit surface, get germinates and mycelia grow into the tissues of fruit. The infection produces a layer of black spores on the fruit surface. The fruit becomes soft, watery and brown spots develop on the fruit. In culture on PDA medium it is heavily growing and spreading. It produces sporangia with spores, and then it becomes brownish black with maturity of fungal colony. For biocontrol of soft rot fungi, 20% methanolic extract is more effective than 5, 10, and 15% concentrations. The methanolic extract showed 100% inhibition of both soft rot fungi when compared to water extract. For the first time fungal extracts were used to control the soft rot fungus causing disease in Jackfruits.

Thermal modification processes have been developed to increase the biological durability and dimensional stability of wood. The aim of this paper was to study the influence of ThermoWood® treatment intensity on improvement of wood decay resistance against soil-inhabiting micro-organisms, brown/white rots and termite exposures. All of the tests were carried out in the laboratory with two different complementary research materials. The main research material consisted of ash (Fraxinus excelsior L.) wood thermally modified at temperatures of 170, 200, 215 and 228 °C. The reference materials were untreated ash and beech wood for decay resistance tests, untreated ash wood for soil bed tests and untreated ash, beech and pine wood for termite resistance tests. An agar block test was used to determine the resistance to two brown-rot and two white-rot fungi according to CEN/TS 15083-1 directives. Durability against soil-inhabiting micro-organisms was determined following the CEN/TS 15083-2 directives, by measuring the weight loss, modulus of elasticity (MOE) and modulus of rupture (MOR) after incubation periods of 24, 32 and 90 weeks. Finally, Reticulitermes santonensis species was used for determining the termite attack resistance by non-choice screening tests, with a size sample adjustment according to EN 117 standard directives on control samples and on samples which have previously been exposed to soil bed test. Thermal modification increased the biological durability of all samples. However, high thermal modification temperature above 215 °C, represented by a wood mass loss (ML%) due to thermal degradation of 20%, was needed to reach resistance against decay comparable with the durability classes of ‘‘durable’’ or ‘‘very durable’’ in the soil bed test. The brown-rot and white-rot tests gave slightly better durability classes than the soil bed test. Whatever the heat treatment conditions are, thermally modified ash wood was not efficient against termite attack neither before nor after soft rot degradation.

Renewable products can ensure environmental sustainability, human health, and reduce the use of traditional products that have toxic compounds in their formulation. Therefore, the research aimed to evaluate the biological resistance of Pinus elliottii wood against xylophagous fungi and termites through impregnation with silica bioparticles (SiO2) obtained from rice husks. To obtain the silica, the material underwent chemical treatment, two cycles of acid leaching with hydrochloric acid, and heat treatment at 500 °C, 550 °C or 600 °C. The purity of the silica obtained was characterized by X-ray fluorescence technique (XRF), and the mean particle size by scanning electron microscopy (SEM). SiO2 was applied to the specimens at concentrations of 0.5%, 1.0%, and 2.0%, and the impregnated samples were subjected to tests with brown rot fungi (Gloeophyllum trabeum, Rhodonia placenta and Neolentinus lepideus), soft rot (taken from natural forest soil) and xylophagous termites (Nasutitermes corniger and Cryptotermes brevis). The thermal treatments promoted the obtainment of high purity bioparticles, with value of approximately 90% and diameter of 263.7 nm. In the termite test, the smallest loss of mass and damage were for the impregnated samples. Termite mortality increased with the concentration of solutions. SiO2 was not effective against xylophagous fungi, with no difference between treatments and controls, indicating that resistance was inherent in the wood itself.

Multi-walled carbon nanotubes (MWCNTs) have significant environmental concerns for soil, water and ecosystems. Since their harmful effects on human health, including respiratory disease, they are considered dangerous substances. Thus, it is required to discover a constructive solution to decrease of MWCNT toxicity. Due to their high degradability, white rot and soft rot fungi have been used in the biodegradation of various pollutants. In this study, we evaluated the ability of native Iranian white and soft rot fungi to degrade MWCNTs mainly by means of dynamic light scattering (DLS) and surface charge measurement. In this regard, growth kinetics, CO2 and protein production, size, surface charge and pH change were measured. Continuous Raman spectroscopy, scanning electron microscope (SEM) and transmission electron microscope (TEM) imaging were carried out to detect the process of degradation. The results showed that the morphology, arrangement, size and diameter of MWCNTs were modified due to fungal degradation. The cytotoxicity of treated MWCNTs was determined by the MTT test. The results indicated that native Iranian white and soft rot fungi have a significant ability for degradation of MWCNTs. Furthermore, it could be concluded that fungal treatment could reduce the toxicity of MWCNTs and the best result was achieved in 500 ppm MWCNTs for Trichoderma sp. The activities of oxidative enzymes such as laccase, manganese peroxidase (MnP) and lignin peroxidase (LiP) were measured to determine the mechanism of degradation. Enzyme assays have suggested that these oxidising enzymes especially laccase might play a key role in the degradation of MWCNTs in white rot and soft rot fungi. The overall results confirmed the reproductive ability of Trichoderma sp. WF29 as a soft rot and two white rot fungi Irpex lacteus WF36 and Trametes versicolor to degrade MWCNT.

Acetylation is an environmental friendly method to modify wood properties and protect it against biological attack. Many researches have been done in this field. However, no concern was paid for mode of protection in acetylated wood. This research had been aimed to study mode of action in acetylated wood by investigating on weight and MOE loss, chemical alteration in cell wall due to microbial attack, IRspectroscopy, microcalorimetry, determination of fungal biomass by using ergosterol assay and FDA hydrolysis and enzyme assays. Beech and Scots pine wood samples were acetylated by using acetic anhydride at temperature 80-120°C for 180min. Acetylated wood samples were tested under soil bed test condition, field and basidiomycete trials. Results showed that the losses of weight and MOE decreased at increasing weight gains. Soil bed test revealed that the acetylation of beech wood at above 8% and pine wood at above 10% inhibits soil microorganisms in attacking wood and their activities reached to nil at higher weight gains. A test with the white rot fungus (T. versicolor) showed that the weight loss decreased at raising weight gains. Weight gains of above 10% inhibited fungal decay in beech wood and it reached to zero at higher weight gains. Microscopical studies of wood from soil bed samples, field trials and basidiomycete (white- and brown-rot) tests showed that fungi could colonize acetylated and non-acetylated wood. However, measurements of fungal biomass by using ergosterol assays in those woods and fluorescein diacetate in white rottests showed a rapid colonization of fungal hyphae at early stages of incubation and decreased amount of fungal biomass at raising weight gains.Results showed that fungal colonization is influenced by the acetylation. Biological activities were measured in wood by using microcalorimetry. The reduction of thermal powers and measured amounts of energy production in acetylated wood revealed that activities of microorganisms were influenced by the acetylation and their activities decreased at increased degree of the acetylation. Microscopy of field trial samples showed that the acetylation of wood was affected the growth of soil microorganisms and protected wood against soil microorganisms during a long period of exposure (350 weeks) to soil.Different types of decay in field samples showed successional activities of soft- and white-rot fungi and also bacteria. Soil bed test showed a synergism between soil fungi and bacteria in wood. It was revealed that bacteria followed hyphal traces in cells and associated with fungi in wood degradation. Chemical analyses of acetylated wood in soil bed samples showed a significant effect of the acetylation on removal of cell wall components. The analyses showed a reduction in removal of cell wall components at increased weight gains. Results revealed that removal of the cell wall components reduced considerably in beech wood at weight gains above 8% and in Scots pine samples at above 10%. Study on patterns and phenol ogy of white- and brown-rot decay on acetylated wood showed no difference of decay patterns between acetylated and non-acetylated wood, however decay patterns appear more later in acetylated wood.