ATR-FTIR Study of Alaska Yellow Cedar Extractives and Relationship with Their Natural Durability

New approaches for assessing wood durability are needed to help categorize decay resistance as timber utilization shifts towards plantations or native forest regrowth that may be less durable than original native forest resources. This study evaluated attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy combined with principal component analysis (PCA) for distinguishing between groups of Alaska yellow cedar (Cupressus nootkatensis) wood for susceptibility to two decay fungi (Gloeophyllum trabeum and Rhodonia placenta) and the eastern subterranean termite (Reticulitermes flavipes). Alaska yellow cedar durability varied with test organisms, but the majority of samples were highly resistant to fungal and termite attack. Weight losses and extractives yield using sequential extractions (toluene:ethanol > ethanol > hot water) showed moderate to weak relationships. PCA analysis revealed limited ability to distinguish amongst levels of wood durability to all tested organisms. The absence of non-resistant samples may have influenced the ability of the chemometric methods to accurately categorize durability.

Collection and Characterization of Wood Decay Fungal Strains for Developing Pure Mycelium Mats

Wood decay fungi (WDF) seem to be particularly suitable for developing myco-materials due to their mycelial texture, ease of cultivation, and lack of sporification. This study focused on a collection of WDF strains that were later used to develop mycelium mats of leather-like materials. Twenty-one WDF strains were chosen based on the color, homogeneity, and consistency of the mycelia. The growth rate of each strain was measured. To improve the consistency and thickness of the mats, an exclusive method (newly patented) was developed. The obtained materials and the corresponding pure mycelia grown in liquid culture were analyzed by both thermogravimetric analysis (TGA) and scanning electron microscopy (SEM) to evaluate the principal components and texture. TGA provided a semi-quantitative indication on the mycelia and mat composition, but it was hardly able to discriminate differences in the production process (liquid culture versus patented method). SEM provided keen insight on the mycelial microstructure as well as that of the mat without considering the composition; however, it was able to determine the hyphae and porosity dimensions. Although not exhaustive, TGA and SEM are complementary methods that can be used to characterize fungal strains based on their desirable features for various applications in bio-based materials. Taking all of the results into account, the Fomitopsis iberica strain seems to be the most suitable for the development of leather-like materials.

The Resistance of Modified Manii Wood with Boric acid and Chitosan/Glycerol and Heating Against Fungi and Termites

Manii wood (Maesopsiss eminii Engl.) is a fast grown species that has low durability (class IV) and requires preservation. Boric acid is generally used in wood preservation. However, its application needs to be combined with other treatments to prevent from leaching. This study aimed to evaluate the resistance of manii wood after double impregnation of boric acid and chitosan or glycerol and heat treatment. Heating temperatures were 70ºC and 140ºC. The durability test was carried out against white rot fungus (Schizophyllum commune), dry wood termites (Cryptotermes cynocephalus), subterranean termites (Coptotermes curvignathus) according to SNI 7207-2014 standard, and field test based on ASTM D 1758-08 standard. The retention of boric acid in manii wood was 15,2 ± 1,0 kg ma−3. The interaction of boric acid and chitosan/glycerol impregnations and heat treatment significantly affected the wood resistance against decay fungi and termites. Impregnation of boric acid and glycerol by heating at 140ºC increased the resistance of wood against dry wood and subterranean termites. Double impregnation of boric acid and chitosan followed by heating at 140ºC was the best treatment in this research that improved significantly the resistance of manii wood against white rot fungi, dry wood termites and subterranean termites.

The Resistance of Heat-Modified Fast Growing Woods Against Decay Fungi

Fast growing woods from plantations forest generally have low quality and require improvement to resist degrading organisms. This study aimed to evaluate the resistance of heat-modified sengon, jabon, mangium, and short rotation teak woods against decay fungi. Heat treatment was applied at two different temperatures (150 °C and 180 °C) and for three different times (0, 2, and 6 hours). The decay resistance test used white rot (Schizophyllum commune Fr) and brown rot (Tyromyces palustris) fungibased on modified SNI 01-7207-2014 standard. The chemical analysis of heat-modified wood used Gas Chromatography-Mass Spectrometry. The results showed that the white rot fungal resistance was significantly affected by the interaction of wood species, temperature and period of heating, while the brown rot fungal resistance was significantly affected by the interaction of wood species and heating temperature. Heating at 180 °C for 6 hours increased the fungal resistance of sengon, jabon and mangium woods. However, the fungal resistance of teak wood improved by heating at 150 °C for 6 hours. The durability improvement of the heat-modified woods were suspected due to the appearance or increase of antifungal substances such as benzoic acid, sinapaldehyde, vanillin and 2-methylantraquinone.

Analysis of pigments and damages for the 19th century White-robed Water-moon Avalokitesvara Painting in Gongju Magoksa Temple, Republic of Korea

The White-Robed Water-Moon Avalokiteshvara painting displayed on the rear wall of Daegwangbojeon (main hall) in Magoksa temple, is one of the representative Buddhist paintings in the late nineteenth century of Korea, and a valuable resource for understanding the coloring techniques and characteristics of Buddhist paintings in terms of expression and description in landscape painting. In this painting, the contours and colored surface remain undamaged, but blistering and exfoliation appear on some pigment layers. Furthermore, the partial decomposition of wooden materials due to wood-decay fungi and insect damage were found on the rear wall requiring proper treatment for long-term conservation. As the results of chromaticity and P-XRF analysis regarding the color pigment layer of the painting, the pigments were classified into ten types. The results suggest that the colors other than blue, green, yellow, red, black, and white were prepared by mixing two or more pigments. The types of pigments according to colors, were determined as traditional pigments with azurite; emerald green or clinoatacamite; 0 massicot; minium or hematite; Chinese ink; and kaolin, white lead, and gypsum, respectively. Violet and pink colors were assumed to have been prepared by mixing white with blue and red. In most of these pigments, small amounts of synthetic compositions from the modern era were detected at many points.

Genomic and Transcriptomic Insight of Giant Sclerotium Formation of Wood-Decay Fungi

Many fungi form persistent and dormant sclerotia with compact hardened mycelia during unfavorable circumstances. While most of these sclerotia are small in size, Wolfiporia cocos, a wood-decay fungus, grows into giant sclerotia, which are mainly composed of polysaccharides of linear (1→3)-β-D-glucans. To explore the underlying mechanism of converting sophisticated wood polysaccharides for biosynthesis of highly homogenized glucans in W. cocos, we sequenced and assembled the genome of a cultivated W. cocos strain (WCLT) in China. The 62-Mb haploid genome contains 44.2% repeat sequences, of which, 48.0% are transposable elements (TEs). Contrary to the genome of W. cocos from North America, WCLT has independently undergone a partial genome duplication (PGD) event. The large-scale TE insertion and PGD occurrence overlapped with an archeological Pleistocene stage of low oxygen and high temperature, and these stresses might have induced the differences in sclerotium due to geographical distribution. The wood decomposition enzymes, as well as sclerotium-regulator kinases, aquaporins, and highly expanded gene families such as NAD-related families, together with actively expressed 1,3-β-glucan synthase for sclerotium polysaccharides, all have contributed to the sclerotium formation and expansion. This study shall inspire further exploration on how fungi convert wood into simple glucans in the sclerotium of W. cocos.

DNA metabarcoding reveals host-specific communities of arthropods residing in fungal fruit bodies

Biological communities within living organisms are structured by their host's traits. How host traits affect biodiversity and community composition is poorly explored for some associations, such as arthropods within fungal fruit bodies. Using DNA metabarcoding, we revealed the arthropod communities in living fruit bodies of eleven wood-decay fungi from boreal forests and investigated how they were affected by different fungal traits. Arthropod diversity was higher in fruit bodies with a larger surface area-to-volume ratio, suggesting that colonisation is crucial to maintain arthropod populations. Diversity was not higher in long-lived fruit bodies, most likely because these fungi invest in physical or chemical defences against arthropods. Arthropod community composition was structured by all measured host traits, namely fruit body size, thickness, surface area, morphology and toughness. Notably, we identified a community gradient where soft and short-lived fruit bodies harboured more true flies, while tougher and long-lived fruit bodies had more oribatid mites and beetles, which might reflect different development times of the arthropods. Ultimately, close to 75% of the arthropods were specific to one or two fungal hosts. Besides revealing surprisingly diverse and host-specific arthropod communities within fungal fruit bodies, our study provided insight on how host traits structure communities.

Evaluation of Heartwood Extracts Combined with Linseed Oil as Wood Preservatives in Field Tests in Southern Mississippi, USA

Heartwood extracts of naturally durable wood species are often evaluated as alternatives to chemical wood preservatives, but field data from long-term performance testing are lacking. The current study evaluated the long-term (five-year) performance of two non-durable wood species treated with heartwood extracts of either Tectona grandis, Dalbergia sissoo, Cedrus deodara, or Pinus roxburghii alone or combined with linseed oil. Stakes (45.7 × 1.9 × 1.9 cm) and blocks (12.5 × 3.75 × 2.5 cm) cut from the sapwood of cottonwood and southern pine were vacuum-pressure impregnated with the individual heartwood species extract, linseed oil, or a mixture of each individual wood extract and linseed oil. For comparison, solid heartwood stakes and blocks of the wood species used to obtain extracts were also included in the tests. All samples were exposed for five years to decay and termites at a test site in southern Mississippi using ground contact (AWPA E7) and ground proximity (AWPA E26) tests. Results showed that extract-oil mixtures imparted higher termite and decay resistance in cottonwood and southern pine than linseed oil only or the individual heartwood species extract in both tests. However, these treatments were as not effective as to commercially used wood preservatives, copper naphthenate (CuN) or disodium octaborate tetrahydrate (DOT) in either test. Moreover, solid heartwood P. roxburghii stakes were completely decayed and attacked by termites after five years in the ground contact test. In contrast, C. deodara stakes were slightly attacked by termites and moderately attacked by decay fungi. However, T. grandis and D. sissoo stakes showed slight to superficial attack by termites and decay fungi in ground contact test. In contrast, T. grandis and D. sissoo blocks showed slight decay fungi attack in above-ground tests. However, termites did not attack T. grandis, D. sissoo, and C. deodara blocks. However, decay fungi moderately attacked C. deodara blocks, and P. roxburghii blocks were severely attacked by decay fungi and termites in the above-ground test.

Decaying hardwood associated fungi showing signatures of polyethylene degradation

The involvement of wood decay fungi and the importance of their enzymes in polyethylene degradation is well documented. Therefore, decay-resistant hardwood associated fungi should be better degraders with their versatile enzymatic systems. In the current study, decaying hardwood associated fungi were isolated and their ability to degrade low-density polyethylene (LDPE) was assessed. Thirty-three isolates were identified by sequencing the internal transcribed spacer region of nuclear ribosomal DNA. Randomly selected isolates were tested for laccase producing abilities. Three species were selected to test their potentials in LDPE sheet degradation. Fungi were incubated in Czapek-Dox broth containing 20-micron LDPE sheets at room temperature for 60 days. The biodegradation signatures were assessed by analyzing the changes in structural characteristics of LDPE using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), percent reduction of tensile properties, and weight loss. FTIR analysis revealed changes in certain functional groups compared with the control, indicating chemical changes resulting from the treatment. LDPE sheets incubated with fungi showed cracks and holes under SEM analysis, percent reduction in tensile properties, and weight loss, which are the signatures of degradation. This study revealed that the hardwood decaying basidiomycetes, Phlebiopsis flavidoalba, Schizophyllum commune, and Phanerodontia chrysosporium have the potential for in vitro LDPE degradation.