Moisture sorption and decay resistance of HDPE based wood plastic composites (WPC) made from poplar, Douglas-fir, black locust, white oak, and ponderosa pine were investigated. Dimensional stability ...of WPC made from poplar was poor while black locust performed extremely well. There were no significant gravimetric differences in composites produced using Douglas-fir, poplar, or pine exposed to
Gloeophyllum
trabeum (brown rot). However,
Trametes
versicolor (white rot) produced significantly higher weight losses on HDPE/poplar composites, while Douglas-fir based WPC were less susceptible to this fungus. FTIR spectroscopy showed that white rot selectively decomposed lignin while brown rot degraded both polysaccharides and lignin. Cellulose and hemicelluloses content decreased in WPC exposed to brown rot. Chitin in the fungi cell walls increase polysaccharide content of decayed WPC. The results suggest that poplar and pine would be the preferred wood species for WPC production for applications where conditions would not be suitable for white rot.
Particleboards produced with other lignocellulosic materials, beyond wood, are promising products for the furniture and building construction components, as doors, lining, floor, partitions, and ...coverings. However, there is little information about the resistance of them to xylophagous organisms. This is important due the different uses of particleboards, where they will be subject to attacks by decaying organisms, which can affect a structure and put people at risk. The present study aims to determine the biological resistance of particleboard produced with pine, sugarcane bagasse and malva particles to xylophagous organisms. The particleboard was produced with different proportions of pine wood heat treated at 200 °C and malva fiber (outer layers) and sugarcane bagasse core glued with an adhesive based on polyurethane from castor oil. No-choice and choice feeding tests with dry wood (Cryptotermes brevis) and conehead (Nasutitermes corniger) termites were carried out for the resistance test to xylophagous organisms, in addition to a test with rotting fungi which cause brown (Gloeophyllum trabeum and Rhodonia placenta) and white rot (Irpex lacteus and Trametes versicolor). The trial with dry wood termites showed low mass losses, regardless of the proportions applied. The mass losses were accentuated for the test with conehead termite, having the particleboard composed of 100% pine been the most resistant among the boards tested. The greatest mass losses for fungal resistance were caused by Gloeophyllum trabeum. The particleboard produced with 100% pine (outer layer) showed the highest resistance to the tested xylophagous organisms.
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.
The wood of poplar species is generally perceived as susceptible to decay, however, poplar is still widely used as columns in traditional Chinese buildings. Understanding how decay affects the ...compressive properties of this material will help engineers better assess wood condition during routine inspection and maintenance. The effects of decay on compressive properties of Chinese poplar were explored using a brown rot decay fungus (Gloeophyllum trabeum). Changes in compression strength were fairly linear and more closely correlated with mass loss (R 2= 0,75). The results suggest that residual compressive strength could be roughly predicted using wood density as a surrogate measure.
Here we describe the first crystal structure of a beta‐1,4‐endoglucanase from a brown‐rot fungus, Gloeophyllum trabeum GtCel45A, which belongs to subfamily C of glycoside hydrolase family 45 (GH45). ...GtCel45A is ~ 18 kDa in size and the crystal structure contains 179 amino acids. The structure is refined at 1.30 Å resolution and Rfree 0.18. The enzyme consists of a single catalytic module folded into a six‐stranded double‐psi beta‐barrel domain surrounded by long loops. GtCel45A is very similar in sequence (82% identity) and structure to PcCel45A from the white‐rot fungus Phanerochaete chrysosporium. Surprisingly though, initial hydrolysis of barley beta‐glucan was almost twice as fast in GtCel45A as compared to PcCel45A.
We described the crystal structure of a GH45 subfamily C member from a brown‐rot fungus, compared it to a nearly identical subfamily C member from a white‐rot fungus, made sequence comparisons, and created consensus sequences for all GH45 subfamilies to highlight strictly conserved residues. Additionally, enzymatic degradation rate of barley betaglucan was compared between the two subfamily C members.
Among wood‐degrading fungi, lineages holding taxa that selectively metabolize carbohydrates without significant lignin removal (brown rot) are polyphyletic, having evolved multiple times from ...lignin‐removing white rot fungi. Given the qualitative nature of the ‘brown rot’ classifier, we aimed to quantify and compare the temporal sequence of carbohydrate removal among brown rot clades. Lignocellulose deconstruction was compared among fungi using distinct plant substrates (angiosperm, conifer, grass). Specifically, aspen, pine and corn stalk were harvested over a 16‐week time series from microcosms containing Gloeophyllum trabeum, Fomitopsis pinicola, Ossicaulis lignatilis, Fistulina hepatica, Serpula lacrymans, Wolfiporia cocos or Dacryopinax sp. After quantifying plant mass loss, a thorough compositional analysis was complemented by a saccharification test to determine wood cell wall accessibility. Mass loss and accessibility varied depending on fungal decomposer and substrate, and trajectories of loss for hemicellulosic components and cellulose differed among plant tissue types. At any given stage of decomposition, however, lignocellulose accessibility and the fraction remaining of carbohydrates and lignin within a plant tissue type were generally the same, regardless of fungal isolate. This suggests that the sequence of plant component removal at this typical scale of characterization is shared among these brown rot lineages, despite their diverse genomes and secretomes.
Brown rot fungi are primary decomposers of wood and litter in northern forests. Relative to other microbes, these fungi have evolved distinct mechanisms that rapidly depolymerize and metabolize ...cellulose and hemicellulose without digesting the more recalcitrant lignin. Its efficient degradative system has therefore attracted considerable attention for the development of sustainable biomass conversion technologies. However, there has been a significant lack of genetic tools in brown rot species by which to manipulate genes for both mechanistic studies and engineering applications. To advance brown rot genetic studies, we provided a gene-reporting system that can facilitate genetic manipulations in a model fungus
. We first optimized a transformation procedure in
, and then transformed the fungus into a constitutive laccase producer with a well-studied white rot laccases gene (from
). With this, we built a gene reporting system based on laccase gene's expression and its rapid assay using an 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) indicator dye. The laccase reporter system was validated robust enough to allow us to test the effects of donor DNA's formats, protoplast viability, and gene regulatory elements on transformation efficiencies. Going forward, we anticipate the toolset provided in this work would expedite phenotyping studies and genetic engineering of brown rot species.
One of the most ubiquitous types of decomposers in nature, brown rot fungi, has lacked robust genetic tools by which to manipulate genes and understand its biology. Brown rot fungi are primary decomposers in northern forests helping recycle the encased carbons in trees back to ecosystem. Relative to other microbes, these fungi employ distinctive mechanisms to disrupt and consume the lignified polysaccharides in wood. Its decay mechanism allows fast, selective carbohydrate catabolization, but without digesting lignin-a barren component that produces least energy trade back for fungal metabolisms. Thus, its efficient degradative system provides a great platform for developing sustainable biotechnologies for biomass conversions. However, progress has been hampered by the lack genetic tools facilitating mechanistic studies and engineering applications. Here, the laccase reporter system provides a genetic toolset for genetic manipulations in brown rot species, which we expect would advance relevant genetic studies for discovering and harnessing the unique fungal degradative mechanisms.
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 (SiO
2
) 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). SiO
2
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. SiO
2
was not effective against xylophagous fungi, with no difference between treatments and controls, indicating that resistance was inherent in the wood itself.
Poplar wood (
Populus ussuriensis Kom) was modified by a novel combined two-step treatment to improve its decay resistance. Maleic Anhydride (MAN) was first employed to swell and bond to wood cell ...wall, and then mixed monomers of glycidyl methacrylate/methyl methacrylate (GMA/MMA) were used to graft copolymerization within wood cell lumen. The swelling and bonding of cell wall by MAN, interfacial compatibility between resultant polymer from GMA/MMA monomers and wood cell wall, and decay resistance of all composites were tested and analyzed by Scanning electron microscopy–Energy dispersive X-ray (SEM–EDX), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) apparatus. The results indicate that the volume of poplar wood treated by MAN swells about 9% with about 15% of weight percent gain, and MAN chemically bonds to the cell wall through substitution reaction with hydroxyl group, and the grafting adduct mainly remains as an amorphous form. The resultant Poplar-MAN shows improved decay resistance of 69.79% against brown fungus (
Gloeophyllum trabeum (Pers. ex Fr.) Murr.) and 81.42% against white fungus (
Phanerochaete chrysosporium Burdsall.) over those of untreated Poplar, respectively. After the combined two-step treatment, GMA and MMA are copolymerized within wood cell lumen, and the resultant polymer is also grafted onto wood cell wall, resulting in the improvement of interfacial compatibility between polymer and wood substance without obvious gaps. The decay resistance of the resultant composite from the combined two-step treatment against the brown decay fungus and the white decay fungus is improved by 97.64% and 99.17%, respectively, compared with those of untreated poplar wood; and also more excellent than those of MMA treated wood, GMA/MMA monomers treated wood, organic 3-Iodo-2-Propynyl Butyl Carbamate (IPBC) treated wood and inorganic boron compounds treated wood, respectively.
► A novel combined two-step way for improvement of wood decay resistance is designed. ► It combines swelling and grafting of cell wall with functional monomers. ► Several characterizations prove the swell-bonding and graft polymerization. ► Such way contributes to the remarkable improvement of decay resistance of wood.
The basidiomycete fungus Gloeophyllum trabeum causes a typical brown rot and is known to use reactive oxygen species in the degradation of cellulose. The extracellular Cel12A is one of the few ...endo-1,4- beta -glucanase produced by G. trabeum. Here we cloned cel12A and heterologously expressed it in Aspergillus niger. The identity of the resulting recombinant protein was confirmed by mass spectrometry. We used the purified GtCel12A to determine its substrate specificity and basic biochemical properties. The G. trabeum Cel12A showed highest activity on beta -glucan, followed by lichenan, carboxymethylcellulose, phosphoric acid swollen cellulose, microcrystalline cellulose, and filter paper. The optimal pH and temperature for enzymatic activity were, respectively, 4.5 and 50 degree C on beta -glucan. Under these conditions specific activity was 239.2 plus or minus 9.1 U mg-1 and the half-life of the enzyme was 84.6 plus or minus 3.5 hours. Thermofluor studies revealed that the enzyme was most thermal stable at pH 3. Using beta -glucan as a substrate, the Km was 3.2 plus or minus 0.5 mg mL-1 and the Vmax was 0.41 plus or minus 0.02 mu mol min-1. Analysis of the effects of GtCel12A on oat spelt and filter paper by scanning electron microscopy revealed the morphological changes taking place during the process.
PDF
