Gloeophyllum Trabeum Research Articles

Fungal decay-provoked degradation of cross-linking networks in phenol-formaldehyde adhesive: From fragmentation process towards damaged mechanical robustness

The mechanical robustness of structural adhesives as represented by phenol formaldehyde (PF) adhesive is vital for the safe service of engineered wood/bamboo products facing environmental aggressors. Here, fungal decay-provoked hazard towards the mechanical robustness of PF adhesive was demonstrated, which was usually overlooked in previous works. Obtained results proved that the white rot (Trametes versicolor, T. versicolor) and brown rot (Gloeophyllum trabeum, G. trabeum) fungus can both grow on the surface of cured commercial PF adhesive. An evident oxidization can only be observed on the T. versicolor-decayed PF adhesive, as along with the appearance of 2,6-bis(1,1-dimethylethyl)-1,4-benzenediol after decay. It further demonstrated the ruptured and oxidized cross-linking structures. The evident degradation of PF adhesive can be assigned to the favored activity of laccase (40.9 U mL−1) and lignin peroxidase (60.5 U mL−1) during the decay of T. versicolor. The elastic modulus and hardness of PF adhesive reduced by over 31.6 % and 50.2 %, respectively, which is also accompanied by the elevation in the creep deformation (45.4 %), after a 40-day T. versicolor decay. This work revealed the decay-sensitivity of PF adhesive, and the cleavage of cross-linking structures is the major trigger for the degraded mechanical robustness of PF adhesive after decay.

A cellulose-binding domain specific for native crystalline cellulose in lytic polysaccharide monooxygenase from the brown-rot fungus Gloeophyllum trabeum

Cellulose-binding domains (CBDs) play a vital role in cellulose degradation by enzymes. Despite the strong ability of brown-rot fungi to degrade cellulose in wood, they have been considered to lack or have a low number of enzymes with CBD. Here, we report the C-terminal domain of a lytic polysaccharide monooxygenase from the brown-rot fungus Gloeophyllum trabeum (GtLPMO9A-2) functions as a CBD, classified as a new family of carbohydrate-binding module, CBM104. The amino acid sequence of GtCBM104 shows no similarity to any known CBDs. A BLAST search identified 84 homologous sequences at the C-terminus of some CAZymes, mainly LPMO9, in basidiomycetous genomes. Binding experiments revealed GtCBM104 binds selectively to native crystalline cellulose (cellulose I), but not to artificially modified crystalline or amorphous cellulose, while the typical fungal CBD (CBM1) bound to all cellulosic materials tested. The adsorption efficiency of GtCBM104 to cellulose I was >20-times higher than that of CBM1. Adsorption tests and microscopic observations strongly suggested that GtCBM104 binds to the hydrophilic regions of cellulose microfibrils, while CBM1 recognizes the hydrophobic surface. The discovery of GtCBM104 strongly suggests that the contribution of CBD to the cellulose enzymatic degradation mechanism of brown-rot fungi is much larger than previously thought.

Biocalorimetry-aided monitoring of fungal pretreatment of lignocellulosic agricultural residues

The present study aimed to investigate whether and how non-invasive biocalorimetric measurements could serve for process monitoring of fungal pretreatment during solid-state fermentation (SSF) of lignocellulosic agricultural residues such as wheat straw. Seven filamentous fungi representing different lignocellulose decay types were employed. Water-soluble sugars being immediately available after fungal pretreatment and those becoming water-extractable after enzymatic digestion of pretreated wheat straw with hydrolysing (hemi)cellulases were considered to constitute the total bioaccessible sugar fraction. The latter was used to indicate the success of pretreatments and linked to corresponding species-specific metabolic heat yield coefficients (YQ/X) derived from metabolic heat flux measurements during fungal wheat straw colonisation. An YQ/X range of about 120 to 140 kJ/g was seemingly optimal for pretreatment upon consideration of all investigated fungi and application of a non-linear Gaussian fitting model. Upon exclusion from analysis of the brown-rot basidiomycete Gloeophyllum trabeum, which differs from all other here investigated fungi in employing extracellular Fenton chemistry for lignocellulose decomposition, a linear relationship where amounts of total bioaccessible sugars were suggested to increase with increasing YQ/X values was obtained. It remains to be elucidated whether an YQ/X range being optimal for fungal pretreatment could firmly be established, or if the sugar accessibility for post-treatment generally increases with increasing YQ/X values as long as “conventional” enzymatic, i.e. (hemi)cellulase-based, lignocellulose decomposition mechanisms are operative. In any case, metabolic heat measurement–derived parameters such as YQ/X values may become very valuable tools supporting the assessment of the suitability of different fungal species for pretreatment of lignocellulosic substrates.Key points• Biocalorimetry was used to monitor wheat straw pretreatment with seven filamentous fungi.• Metabolic heat yield coefficients (YQ/X) seem to indicate pretreatment success.• YQ/X values may support the selection of suitable fungal strains for pretreatment.

Antifungal activity of heat-treated wood extract against wood decay fungi

Using heat treatment for wood protection has been driven to maturity, but the role of heat-treated wood extracts in decay resistance has lacked attention. To assess the potential of heat-treated wood extract for wood preservation, the antifungal activity of the extract against wood decay fungi and the effects of the extract on fungal wood degrading enzyme activity and cell membrane integrity were tested. Small shavings generated during the processing of larch (Larix gmelinii (Rupr.) Kuzen) were heat-treated and extracted. The antifungal activity of extract against wood decay fungi and decay resistance of extract impregnated wood were tested to assess their potential. The effect of extracts on the enzyme activity of the white-rot fungus, Trametes versicolor (L.) Lloyd and the brown-rot fungus, Gloeophyllum trabeum (Pers.: Fr.) Murr. for wood degradation was assessed by detecting the activity of cellulose, hemicellulose, and ligninase of fungi incubated with extract. The effect of extracts on the integrity of cell membranes of fungi was assessed by staining with propidium iodide (PI) and the leakage detection of nucleic acid and protein in fungi after exposure to extract. The toxicity to freshwater luminescent bacteria (Vibrio qinghaiensis sp. -Q67) and mouse macrophages (RAW264.7) of the extract impregnated wood leachate was tested and compared with the leachate of the raw wood. The results denoted that the decay resistance of poplar (Populus tomentosa Carr.) wood could be improved by heat-treated larch wood extract, and the effect of the extract impregnated wood leachate on Q67 and RAW264.7 was the same as that of raw wood leachate. The extract inhibited ligninase activity (only for T. versicolor), cellulase activity, and respiratory metabolism of tested fungi, and impaired the membrane integrity. The study identified a potential wood preservative.

Fungal degradation of bamboo treated with crude lake salt and a mixture of borax and boric acid

This study compared the effectiveness of crude lake salt, a traditional preservative used by artisans in Uganda, and borax-boric acid, a conventional preservative, against fungal degradation. Using the European standard, an experiment was set up to determine the durability of Oxytenanthera abyssinica, Oldeania alpina and Bambusa vulgaris treated with 2 % and 6 % crude lake salt and borax-boric acid against Gloeophyllum trabeum, Coniophora puteana and Trametes versicolor. Mass loss comparisons between treated and untreated bamboo samples were made. Durability classes were assigned according to the amount of mass lost. Bamboo samples exposed to G. trabeum had lower surface hyphal coverage compared to those exposed to C. puteana and T. versicolor irrespective of the preservative used. Samples treated with borax-boric acid were in durability class I compared to those treated with crude lake salt that were between class II and III according to European standard. The lowest mass loss for bamboo treated with crude lake salt was 5.9 % in O. abyssinica exposed to G. trabeum. The highest mass loss for bamboo treated with crude lake salt was 14.24 % in B. vulgaris exposed to T. Versicolor. The study confirmed that while artisans use crude lake salt as a traditional preservative, it does not protect against white and brown rot while all concentrations of borax-boric acid provided protection against all fungi.

Valorizing fungal diversity for the degradation of fluoroquinolones

Continued widespread use of antibiotics, especially fluoroquinolones, raises environmental concerns, as its driving bacterial resistance and disrupts microbial ecosystems. Here we investigate the biodegradation of ten fluoroquinolone antibiotics (six for medical use and four for veterinary use) by ligninolytic fungi, including Trametes versicolor, Bjerkandera adusta, Porosterum spadiceum, Irpex lacteus, Pleuroteus ostreatus, Phanerochaete chrysosporium, Pycnoporus cinnabarinus, Ganoderma lucidum, and Gloeophyllum trabeum. The results show significant variations between strains in the efficiency of antibiotic transformation. B. adusta and P. spadiceum were the fungi that most efficiently reduced antibiotic concentrations and were able to totally degrade eight and six antibiotics, respectively, within a 15-day period. T. versicolor and P. ostreatus also showed the ability to effectively degrade antibiotics. Specifically, T. versicolor degraded six out of the ten fluoroquinolone antibiotics by more than 70 %, while P. ostreatus degraded the tested antibiotics between 43 % and 100 %. The remaining antibiotic activity did not always correlate with a reduction in antibiotic concentrations, which points to the presence of post-transformation antimicrobial metabolites. This study also explores the potential mechanisms used by these fungi to remove selected models of fluroquinolones via enzymatic routes, such as oxidation by laccases, heme-peroxidases, and cytochrome P450, or via adsorption on fungal biomass.

The effect of Ralstonia pickettii addition on methylene blue dye biodecolorization by brown-rot fungus Gloeophyllum trabeum

Methylene Blue (MB) is a thiazine group dye frequently used in the textile industry but the difficulty in degrading its molecule poses a significant risk of toxicity to humans. Gloeophyllum trabeum, a brown-rot fungus, has been previously shown to degrade MB. However, the decolorization capacity achieved was relatively poor due to the extended incubation time. This study aimed to improve the MB degradation process by G. trabeum with the addition of Ralstonia pickettii bacteria. The concentrations of R. pickettii added included 2, 4, 6, 8, and 10 mL (1 mL ≈ 1.39 × 108 CFU), while the degradation process was conducted at 30 °C within a 7-day incubation period. The results showed that the highest decolorization percentage was obtained with the addition of 10 mL R. pickettii. The mixed cultures decolorized MB by approximately 85%, while G. trabeum achieved 11% decolorization. The metabolite product produced from the process included C12H13N3O6, C14H14N3S, C12H11N3SO6, C12H11N3SO7, and C22H15N3SO5. Therefore, it was concluded that R. pickettii could enhance the capability of G. trabeum to decolorize MB.

Douglas fir bark: composition, extracts utilization and enzymatic treatment for enrichment of bioactive constituents

Abstract Bark residues from Douglas fir are an abundant resource that is currently used primarily in low-value energy recovery or is landfilled. Bark extractives are rich in diverse compounds like terpenes, fatty acids, phenols, and sugars with potential uses in a variety of high value applications. The study explores the potential of enzymatic hydrolysis to improve phenolic compounds from Douglas fir bark. It also assesses differences in chemical composition among rhytidome, phloem, and comingled bark fractions from an industrial waste pile. Phloem fractions exhibit higher yields of extractives, rhytidome fractions have elevated lignin levels, while the comingled fraction lies between the two except in ash content which was higher than in the separated fractions. Fungal decay tests with Gloeophyllum trabeum and Coniophora puteana on extract treated wood suggest potential for growth inhibition in extracts, about 58–31 % and 30–7% mass loss (in average) respectively, but due to high mass loss at low concentrations an enzymatic modification approach seems crucial for enhanced inhibition. Growth responses in whole-cell fermentation approach display variability depending on the participating microorganisms. Enzymatic hydrolysis with beta-glucosidase improved the antioxidant properties of bark extracts and holds promise for altering the chemical composition and enhancing bioactivity.

Resistance against fungal decay of Scots pine sapwood modified with phenol-formaldehyde resins with substitution of phenol by lignin pyrolysis products

Abstract Phenol-formaldehyde (PF) resins can be impregnated and cured in situ to improve the woods dimensional stability and decay resistance. In search of renewable alternatives, the substitution of phenol by lignin cleavage products (LCP) has been discussed. However, the different chemical nature may affect the performance of the resin against fungal decay, formaldehyde emission, and equilibrium moisture content. In this study, 30 % (w/w) of the phenol in PF resins were substituted by LCP obtained from microwave-assisted pyrolysis. Scots pine sapwood was modified with the resin. The decay resistance against Rhodonia placenta, Gloeophyllum trabeum, and Trametes versicolor was determined. Additionally, effects of specimen organisation within the Petri dish, different substrates, length of leaching, and type of inoculum were studied. Further, the materials water vapor sorption properties and formaldehyde emission were determined. All modifications effectively reduced fungal decay. With 10 % weight percent gain (WPG), initial decay was detected, while 20 % WPG and 30 % WPG provided efficient protection. The substitution of phenol increases the formaldehyde emission. While further reduction in formaldehyde in the resin admixture or formaldehyde scavengers may be required, the method described herein can be used to partly replace fossil-based phenol, while maintaining good fungal resistance.

The first crystal structure of a family 45 glycoside hydrolase from a brown-rot fungus, Gloeophyllum trabeum GtCel45A.

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.

Optimization and antifungal efficacy against brown rot fungi of combined Salvia rosmarinus and Cedrus atlantica essential oils encapsulated in Gum Arabic

The stability, sensitivity, and volatility of essential oils are some of their most serious limitations, and nanoencapsulation has been considered one of the most effective techniques for solving these problems. This research aimed to investigate the incorporation of Salvia rosmarinus Speen and Cedrus atlantica Manetti (MEO) essential oil mixture in Gum Arabic (GA) and to evaluate nanoencapsulation’s ability to promote antifungal activity against two brown rot fungi responsible for wood decay Gloeophyllum trabeum and Poria placenta. The optimization of encapsulation efficiency was performed using response surface methodology (RSM) with two parameters: solid-to-solid (MEO/GA ratio) and solid-to-liquid (MEO/ethanol). The recovered powder characterization was followed by various techniques using a scanning electron microscope (SEM), X-ray diffractometry (XRD), dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FTIR), and thermo-gravimetric analysis (TGA). The optimal nanoencapsulating conditions obtained from RSM were ratios of MEO/GA of 1:10 (w/w) and MEO/ethanol of 10% (v/v), which provided the greatest encapsulation efficiency (87%). The results of SEM, XRD, DLS, FTIR, and TGA showed that the encapsulation of MEO using GA modified particle form and molecular structure and increased thermal stability. An antifungal activity assay indicated that an effective concentration of MEO had an inhibitory effect on brown rot fungi. It had 50% of the maximal effect (EC50) value of 5.15 ± 0.88 µg/mL and 12.63 ± 0.65 µg/mL for G. trabeum and P. placenta, respectively. Therefore, this product has a great potential as a natural wood preservative for sustainable construction and green building.

Evaluation of dowel bearing strength of fungal-decayed cross-laminated timber

ABSTRACT Dowel bearing strength of three cross-laminated timber (CLT) species (Douglas-fir, Norway spruce, spruce pine fir) were periodically assessed through 40 weeks of exposure to two brown rot fungi species (Gloeophyllum trabeum and Rhodonia placenta). Time-dependent regression models were developed to describe the relationship between level of fungal exposure and dowel bearing strength of CLT. Obtained dowel bearing strength values were used to predict the capacity of floor-to-wall CLT connection systems. Predicted strength values were compared with capacity of actual connection systems which were subjected to similar biodeterioration treatments. Significant reductions in the dowel bearing strength of CLT were observed 30 weeks after fungal inoculation. Similar patterns of degradation were observed for both fungi in all three CLT species, but R. placenta was slightly more aggressive than G. trabeum, causing a 16.2 MPa reduction in dowel bearing strength of Douglas-fir after 40 weeks of exposure. Connection capacities estimated using National Design Specification yield models for dowel type fasteners and the dowel bearing strength of fungal-damaged CLT were consistent with observed properties and were within 85% of actual capacity of connections tested, especially in early stages of decay.

In-situ growth of hexaconazole/polydopamine/hexadecyltrimethoxysilane in multi-scale structured wood to prepare superhydrophobic wooden materials with decay resistance

Using the layered channels of wood and its unique mesoporous microstructure, hexaconazole, polydopamine (PDA), and hexadecyltrimethoxysilane (HDTMS) were grown and deposited in-situ on the surface and interior of wood. Using this method, a superhydrophobic wood composite with decay resistance was prepared. Hexaconazole inhibited wood fungal decay, and the mass losses of wood were 0 and 0.06% with a retention of 140 g/m3 after laboratory decay tests for 12 weeks by using Trametes versicolor and Gloeophyllum trabeum, respectively. More importantly, through the oxidative self-polymerization of PDA, the adhesive PDA anchored hexaconazole nanoparticles to form a stable core–shell structure that increased the surface roughness of wood. In addition, based on the association of PDA with hydrophilic –OH groups in cellulose and hemicelluloses in wood, long-chain HDTMS was deposited on the surface of wood to form a superhydrophobic multifunctional wooden material with a water contact angle (WCA) of 154°. Based on its multifunctional and inherent durability, the wood also showed good chemical stability and resistance to UV, high- temperature, and high-humidity environments.

Antifungal Potential and Chemical Composition of Chamaecyparis formosensis and Chamaecyparis obtusa var. formosana Essential Oils in Liquid and Vapor Phases Against 4 Fungal Species

Background Only a few studies have investigated the bioactivity of the essential oils (EOs) of Chamaecyparis formosensis and C. obtusa var. formosana, which are endemic to Taiwan. The wood and leaf EOs extracted from C. obtusa var. formosana had anti-inflammatory and antitermitic effects, respectively, and the twig EO extracted from C. formosensis inhibited the growth of Fusarium oxysporum, Pestalotiopsis funerea, and Ganoderma australe. Methods A poisoned food technique was used to evaluate the antifungal effects of wood and leaf EOs extracted from C. formosensis and C. obtusa var. formosana on brown rot fungus, white rot fungus, and mold. A phytatray chamber assay was conducted to investigate the antifungal activities of the EOs in the vapor phase. Gas chromatography-mass spectrometry was used to examine the chemical constituents of both EOs. Results The leaf EO extracted from C. formosensis primarily contained monoterpene hydrocarbons, whereas the leaf EO extracted from C. obtusa var. formosana primarily contained monoterpene and sesquiterpene hydrocarbons. The wood EOs extracted from C. formosensis and C. obtusa var. formosana primarily contained sesquiterpene hydrocarbons and oxygenated sesquiterpenes. These results indicated that the wood EOs had higher antifungal activity in the liquid phase, whereas the leaf EOs had higher antifungal activity in the vapor phase. Conclusion Wood EOs extracted from C. formosensis and C. obtusa var. formosana have strong antifungal effects against Gloeophyllum trabeum, Lenzites betulina, Trametes versicolor, and Trichoderma sp. Compared with wood EOs, leaf EOs have a greater inhibitory effect on mycelial growth in the vapor phase. In both the liquid and vapor phases, the EOs extracted from C. formosensis and C. obtusa var. formosana serve as effective antifungal agents against pathogenic fungi. Further research is required to elucidate the mechanisms underlying the antifungal activities of EOs in different phases and explore their potential applications.

Simultaneous Thermal Analysis for characterization of fungal depolymerisation of Norway spruce

After fungal decay experiments chemical characterisation of the wood is often a routine and several methodological approaches are available. In this study, we tested if simultaneous thermal analysis (STA) is a valid alternative to traditional wet chemical methods since STA allows significantly smaller sample size and faster analysis. Three model fungi including the brown rot fungi Rhodonia placenta and Gloeophyllum trabeum and the white rot fungus Trametes versicolor were employed in the study using Norway spruce as substrate. The experiment was harvested after 10, 20 and 52 weeks. At each harvest interval, aliquots of the material were characterized by STA and wet chemical methods. The results validated that STA can be effectively used to estimate cell wall composition of brown rot depolymerised wood. However, STA slightly overestimated cellulose at brown rot decay above 50%. The method was not verified for simultaneous white rot because STA only estimated hemicellulose correctly compared to the wet chemical method. Hence, STA is considered suitable for brown rot fungi below 50% mass loss but not for simultaneous white rot because STA did not estimate cellulose and lignin correctly.

Simultaneous Hydrodistillation of Cedrus atlantica Manetti and Salvia rosmarinus Spenn: Optimization of Anti-Wood-Decay Fungal Activity Using Mixture Design Methodology.

Chemical fungicides are often harmful to people and the environment because of their toxicity. The wood protection industry places a high priority on replacing them with natural products. Therefore, this investigation focused on developing a formulation of a binary combination of Salvia rosmarinus Spenn and Cedrus atlantica Manetti obtained by Simultaneous hydrodistillation to protect the wood from decay using a mixture design methodology. The chemical composition of essential oil was identified by gas chromatography coupled with mass spectrometry (GC/MS), and their anti-wood-decay fungal activity was assessed using the macrodilution method against four fungi responsible for wood decay: Coniophora puteana, Coriolus versicolor, Gloeophyllum trabeum, and Poria placenta. The results of GC/MS identified myrtenal as a new component appearing in all binary combinations. The optimum anti-wood-decay fungal activity was observed in a combination of 60% S. rosmarinus and 40% C. atlantica essential oils, providing an effective concentration for 50% of maximal effect (EC50) value of 9.91 ± 1.91 and 9.28 ± 1.55 μg/mL for C. puteana and C. versicolor, respectively. The highest anti-wood-decay fungal activity for G. trabeum and P. placenta was found in the combination of 55% of S. rosmarinus and 45% of C. atlantica essential oils, with EC50 values of 11.48 ± 3.73 and 22.619 ± 3.79 μg/mL, respectively. Combined simultaneous hydrodistillation improved the antifungal effect of these essential oils. These results could be used to improve antifungal activity and protect wood against wood-decay fungi.

Antifungal properties of lauric arginate (LAE) treated wood

Abstract This study investigated the efficacy of lauric arginate (LAE) as a potential preservative against wood deteriorating fungi. First, the antifungal properties of LAE against two brown rot fungi, Gloeophyllum trabeum (G.t.) and Rhodonia placenta (R.p.), and two white rot fungi, Trametes versicolor (T.v.) and Irpex lacteus (I.l.) were examined using malt-agar media as substrate. Then the biological resistance of LAE-treated wood specimens (10, 20, and 25 % LAE solutions) was tested following American Wood Protection Association (AWPA) E10 soil-block test procedures. The in vitro study showed LAE actively inhibited the growth of all the fungi tested compared to growth in control plates but there were no considerable changes observed in the morphology of fungi hyphae. Wood impregnated with LAE showed increased weight percent gain as a function of treatment concentration. Characterization of LAE-treated wood on a thermogravimetric analyzer showed LAE shifted the thermal degradation temperatures to lower stages but did not significantly improve the thermal stability of the treated specimen. LAE in wood significantly suppressed fungus growth, leading to decreased mass loss but it also leached out from wood specimens during fungi exposure.

The effect of bacteria addition on DDT biodegradation by BROWN-ROT fungus Gloeophyllum trabeum

DDT (1,1,1-trichloro-2,2 bis(4-chlorophenyl) ethane) is a synthetic insecticide that has several negative effects on the environment and humans. Therefore, determining an effective method to reduce DDT may give a beneficial impact. Brown-rot fungus, Gloeophyllum trabeum, is well known to have the ability to degrade DDT, even though it might require long-term remediation. In this study, the effect of the addition of bacteria on the biodegradation of DDT by G. trabeum had been investigated. Bacillus subtilis, Pseudomonas aeruginosa, and Ralstonia pickettii were screened for the bacteria which the volume of bacteria at 1, 3, 5, and 10 mL and the time range of addition of bacteria on days 0, 1, 3, and 5. The addition of B. subtilis, P. aeruginosa, and R. pickettii bacteria into the G. trabeum culture increased DDT biodegradation to approximately 62.02; 74.66; and 75.72%, respectively, in which G. trabeum was only able to degrade DDT by 54.52% for 7 days of incubation. R. pickettii enhanced the degradation process, in which the addition of 10 mL of this bacterium at day 1 possessed the highest value of 92.41% within 7 days of incubation. DDD was detected to be a product metabolite through a dechlorination reaction. This study indicated that mixed cultures of G. trabeum and R. pickettii can be used to degrade DDT.

Improvement of GH10 xylanase activity based on channel hindrance elimination strategy for better synergistic cellulase to enhance green bio-energy production

Xylanase is widely used for the degradation lignocellulosic biomass as an important accessory enzyme. But productive hydrolysis of the recalcitrant lignocellulose also requires for applicable pretreatment with environmental friendliness. Meanwhile, the complicated industrial processes also demand for catalytically efficient enzymes with more resistance to both pH and heating conditions, which barely exist for the wild types. In this study, the dominant mutant H51K/Q118A from Gloeophyllum trabeum derived GtXyn10 (WT) was obtained by directed evolution. Compared to the WT, apart from the impressive pH resistance from pH 1.0–9.0, the dominant mutant H51K/Q118A also exhibited higher specific activity (2.5-fold; 2510 vs. 1010 U/mg), higher catalytic efficiency (2.4-fold; 460 vs. 190 mL/s‧mg), and better thermostability (with t1/2 at 80 °C extend by 10 min). When ‘Seawater + Feton’ pretreatment was applied, the lignin clearance rate reached 62.5%, 86.6% higher than that of feton pretreatment (33.5%). After pretreatment of ‘Seawater + Feton’, Compared with the cellulase-only treatment (159 μmol/g), synergistic hydrolysis with both H51K/Q118A and cellulase (236 μmol/g) increased the fermentable sugar yields from bagasse by 48.4%. In combination with the optimized pretreatment and synergistic hydrolysis of the modified xylanase and cellulase, the fermentable sugar production for green bio-energy was realized with efficiency.

Synergic effect of basalt/wood fiber reinforced polylactic acid hybrid biocomposites against fungal decay

In addition to the traditional fibre-reinforced composites, the investigation of novel composites with significant potential for engineering applications attracts increasing attention. In this study, the decay resistance of basalt and/or wood fibre-reinforced polylactic acid (PLA) biocomposites was evaluated with a soil block test by using white rot fungi, Trametes versicolor (Trv) and Irpex lacteus (Irl), and brown rot fungi, Poria placenta (Pop) and Gloeophyllum trabeum (Glt), and a soft rot fungus, Chaetomium globosum (Chg) after 8 weeks of water submersion. Water absorption rate during the water submission and weight losses after the decay test were determined. Furthermore, decay in biocomposites was characterized by SEM and ATR-FTIR. Results showed that the water absorption increased between 52.4–67.5% for wood fibre composites when compared to basalt fibre-reinforced biocomposites. PLA showed good decay resistance against all fungi attacks. However, as the ratio of basalt and wood fibre in the hybrid biocomposites increased, the fungi resistance decreased. The lowest weight loss, 4.9% was found in the biocomposites containing the highest percentage of basalt fibre. On the other hand, the highest weight loss, 54.2% was observed in the composites containing the highest percentage of wood fibre. The results clearly showed that the hybridization of basalt and wood fibres improves the decay resistance of the biocomposites compared to only wood fibre-reinforced composites. However, as the percentage of wood increased in the composites, the decay resistance decreased. SEM and FTIR analysis confirmed the degradation and revealed the degradation mechanism.