White-rot Fungus Research Articles

Durability Response of Perishable Wood Species after Pressure Impregnation of Extractives-Based Solutions from Naturally Durable Species of Mozambique

Poor natural durability is a key feature hindering the acceptance of most lesser-used wood species, such as Brachstegia spiciformis, Julbernadia globiflora, and Sterculia appendiculata. Generally, the durability of the aforementioned wood species is improved by impregnating its timber with toxic chemicals contained in standard wood preservatives. In this study, eco-friendly wood preservatives based on extractives sourced from sawdust of naturally durable species such as chanfuta (Afzelia quanzensis) and mecrusse (Androstachys jonhsonnii) were used to treat the group of aforementioned perishable wood species. After pressure treatment, the study assessed the durability responses using standardized in vitro durability test methods against brown rot fungus Postia placenta and white rot fungus Trametes versicolor (EN 113-1:2018) and changes of compression strength parallel to the grain (ISO 3787). The samples of perishable timber species were impregnated with separated extractives-based preservatives of chanfuta and mecrusse in five concentrations (0.5 mg/mL, 1.0 mg/mL, 1.5 mg/mL, 2.0 mg/mL, and 2.5 mg/mL). A subset of treated samples was leached (SS-EN 84:2020-E) to infer preservative fixation and also exposed to the same wood-destroying fungi. The results showed that both extractive formulations (chanfuta and mecrusse) changed the durability ratings of perishable species. Firstly, the subset of treated and unleached samples of Brachystegia spiciformis improved from non-durable to moderately durable, Sterculia appendiculata to durable class and Julbernadia globiflora samples improved to very durable class; secondly, after leaching, the durability remained unchanged (non-durable class) for Brachstegia spiciformis but improved from non-durable to a moderately durable class for both Julbernadia globiflora and Sterculia appendiculata timber species against Trametes versicolor. The compression strength of perishable timber species treated with mecrusse increased and decreased in samples treated with chanfuta. The dosage of both wood extractive formulations did not affect compression strength

Oestrogen Detoxification Ability of White Rot Fungus Trametes hirsuta LE-BIN 072: Exoproteome and Transformation Product Profiling

White rot fungi, especially representatives of the genus Trametes spp. (Polyporaceae), are effective destructors of various xenobiotics, including oestrogens (phenol-like steroids), which are now widespread in the environment and pose a serious threat to the health of humans, animals and aquatic organisms. In this work, the ability of the white rot fungus Trametes hirsuta LE-BIN 072 to transform oestrone (E1) and 17β-oestradiol (E2), the main endocrine disruptors, was shown. More than 90% of the initial E1 and E2 were removed by the fungus during the first 24 h of transformation. The transformation process proceeded predominantly in the direction of the initial substrates’ detoxification, with the radical oxidative coupling of E1 and E2 as well as their metabolites and the formation of less toxic dimers in various combinations. A number of minor metabolites, in particular, less toxic estriol (E3), were identified by HPLC-MS. The formation of E1 from E2 and vice versa were shown. The exoproteome of the white rot fungus during the transformation of oestrogens was studied in detail for the first time. The contribution of ligninolytic peroxidases (MnP5, MnP7 and VP2) to the process of the extracellular detoxification of oestrogens and their possible metabolites is highlighted. Thus, the studied strain appears to be a promising mycodetoxicant of phenol-like steroids in aquatic environments.

Effects of hap2 deletion on mnp/vp transcription in Pleurotus ostreatus grown on lignocellulosic substrates.

The regulatory mechanisms governing expression of genes encoding lignin-modifying enzymes (LME) in white-rot fungi remain largely unexplored. Although molecular cloning has identified CCAAT-boxes frequently located 5'-upstream of these genes, their role in transcriptional regulation is not well understood. This study examines the function of hap2, a gene encoding a hypothetical protein homologous to a component of the CCAAT-binding Hap complex, in the white-rot fungus Pleurotus ostreatus. Deletion of hap2 resulted in significantly reduced Mn2+-dependent peroxidase activity and lignin-degrading capacity compared to the parental strain 20b grown on beech wood sawdust (BWS) medium. Real-time PCR revealed that vp2 transcript levels were significantly lower in hap2 deletants than in 20b grown when cultured on the three solid media consisting of BWS, holocellulose, or Avicel, but not on yeast-malt-glucose (YMG) agar plates. Additionally, glutathione S-transferase (GST) pulldown and electrophoretic mobility shift assays demonstrated that recombinant P. ostreatus Hap2, Hap3, and Hap5 expressed in Escherichia coli form a complex capable of binding to the CCAAT sequence 5'-upstream of vp2 in vitro. These results suggest that Hap2, as part of the CCAAT-binding complex, is essential for transcriptional upregulation of vp2 in P. ostreatus growing on lignocellulosic substrates. KEY POINTS: • P. ostreatus hap2 deletants were generated. • Lignin-degrading capacity was significantly reduced in the hap2 deletants. • vp2 was significantly downregulated upon hap2 deletion.

Treatment of Cigarette Butts: Biodegradation of Cellulose Acetate by Rot Fungi and Bacteria

This study demonstrated the biodegradation of two different brands of cigarette butts (CBs), which are primarily composed of cellulose acetate, by four distinct microorganisms. These included the white rot fungus Pleurotus ostreatus, the brown rot fungus Lentinus lepideus, and the bacteria Bacillus cereus and Pseudomonas putida. After 31 days of treatment, weight loss measurements revealed a mass loss of 24–34%, where B. cereus exhibited the greatest efficacy in terms of mass loss for both brands of CBs. Fourier-Transform Infrared Spectroscopy (FTIR), confocal microscopy, and scanning electron microscopy (SEM) confirmed changes in the surface of the CBs, attributable to structural wear and material breakdown, indicating effective biodegradation by the evaluated microorganisms. Furthermore, the analyses confirmed changes in the surface of the CBs, attributable to structural wear and material breakdown, indicating effective biodegradation by the evaluated microorganisms.

Developing Sustainable Wood Preservatives: The Antifungal Efficiency of Afzelia quanzensis Welv. and Androstachys johnsonii Prain Sawdust Extracts from Mozambique

This study aimed to both develop and assess the antifungal efficacy of extractives derived from different sets of sawdust originating from two hardwood species, namely chanfuta (Afzelia quanzensis Welv.) and mecrusse (Androstachys johnsonnii Prain). These hardwood species possess inherent characteristics of high natural durability. The primary objective was to use these extractives to impregnate perishable wood species, enhancing their durability and augmenting their commercial value. Collected wood sawdust was initially sieved to remove residues and unwanted materials and conditioned until 12% moisture content. Subsequently, the sawdust was Soxhlet-extracted using a mixture of organic solvents, including acetone, ethanol, and toluene. After evaporating the solvents, the resulting extractives were used to prepare a preservative solution with ethanol and acetone. The extractive solutions from each wood species were mixed with malt extract agar and then diluted to various concentrations: 0.125 mg/mL, 0.25 mg/mL, 0.5 mg/mL, 1.25 mg/mL, 2.0 mg/mL, and 2.5 mg/mL. For each concentration, fungal plugs from the periphery of actively growing cultures were moved to the centre of Petri dishes and placed in controlled laboratory conditions for incubation. The antifungal efficacy was assessed against specific wood-decaying fungi, including brown rot fungi (Coniophora puteana, Postia placenta, Lentinus lapideus) and white rot (Trametes versicolor). The evaluation involved daily monitoring of the linear expansion along two perpendicular radii for each fungus expressed as a percentage of the empty Petri dish area. The results indicated that the chanfuta extractives inhibited the growth of brown rot fungi at a concentration of 0.25 mg/mL and white rot fungi at 2.0 mg/mL. Similarly, the mecrusse extractives inhibit brown rot at 0.5 mg/mL and white rot at 2.0 mg/mL. The fatty acids Oleic (C18:1) present in the chanfuta extractives solution and linoleic (C18:2) in mecrusse extractives contributed to restraining the fungal growth. These results suggest that sawdust extractives from both wood species exhibit promising potential for creating environmentally friendly wood preservatives, which, with effective treatments, could extend the lifespan of perishable wood species

Novel Basidiomycetous Alcohol Oxidase from Cerrena unicolor—Characterisation, Kinetics, and Proteolytic Modifications

Intracellular alcohol oxidase (AOX) was isolated from the basidiomycetous white rot fungus Cerrena unicolor FCL139. The enzyme was semi-purified (13-fold) using two-step chromatography with 30% activity recovery. The identity of the protein was confirmed by LC-MS/MS analysis, and its MW (72 kDa) and pI (6.18) were also determined. The kinetics parameters of the AOX reaction towards various substrates were analysed, which proved that, in addition to methanol (4.36 ± 0.27% of the oxidised substrate), AOX most potently oxidises aromatic alcohols, such as 4-hydroxybenzyl alcohol (14.0 ± 0.8%), benzyl alcohol (4.2 ± 0.3%), anisyl alcohol (7.6 ± 0.4%), and veratryl alcohol (5.0 ± 0.3%). Moreover, the influence of selected commercially available proteases on the biocatalytic properties of AOX from C. unicolor was studied. It was proved that the digested enzyme lost its catalytic potential properties except when incubated with pepsin, which significantly boosted its activity up to 123%.

Selective Adsorption of Lignin Peroxidase on Lignin for Biocatalytic Conversion of Poplar Wood Biomass to Value-Added Chemicals.

Lignin-first biorefineries aim to maximize the valorization of lignin by prioritizing its conversion over other biomass components. This study investigates the selective adsorption of lignin peroxidase (LiP) isozymes from white rot fungi Phanerochaete chrysosporium on lignin, aiming to enhance the biocatalytic conversion of poplar wood biomass into value-added chemicals. The research focuses on the adsorption characteristics of ten recombinant LiP isozymes, particularly PcLiP03, which exhibited the highest adsorption capacity on lignin and negligible adsorption on cellulose. Adsorption isotherms and structural analyses revealed that hydrophobic interactions significantly contribute to the selective adsorption of PcLiP03. Applying PcLiP03 in a continuous stirring cell system effectively converted lignin in unpretreated poplar wood to 2,6-dimethoxy-1,4-benzoquinone under ambient and mild conditions, highlighting its potential for selective lignin depolymerization in integrated biorefineries. This work underscores the importance of enzyme-substrate interactions and offers a promising approach for more efficient and sustainable biomass utilization.

Identification of Laccase Family of Auricularia auricula-judae and Structural Prediction Using Alphafold.

Laccase is an enzyme that plays an important role in fungi, including lignin degradation, stress defense, and formation of fruiting bodies. Auricularia auricula-judae is a white-rot fungus in the Basidiomycota phylum, capable of delignifying wood. In this study, seven genes belonging to the laccase family were identified through de novo sequencing, containing Cu-Oxidase, Cu-Oxidase_2, and Cu-Oxidase_3 domains. Subsequently, the physical characteristics, phylogenetic relationships, protein secondary structure, and tertiary structure of the laccase family (AaLac1-AaLac7) were analyzed. Prediction of N-glycosylation sites identified 2 to 10 sites in the laccase family, with AaLac7 having the highest number of sites at 10. Sequence alignment and analysis of the laccase family showed high consistency in signature sequences. Phylogenetic analysis confirmed the relationship among laccases within the family, with AaLac3-AaLac4 and AaLac5-AaLac6 being closely positioned on the tree, exhibiting high similarity in tertiary structure predictions. This study identified and analyzed laccase family genes in Auricularia auricula-judae using de novo sequencing, offering a simple method for identifying and analyzing the laccase family in organisms with unknown genetic information.

Fungal and enzymatic pretreatments of bamboo lignocellulose towards high-strength biocomposites: Biological macromolecule/enzyme interaction and bonding enhancement

An energy-intensive and chemical-consuming pretreatment of bamboo is often required to develop its high-performance composites. This study is to evaluate a fungal and enzymatic pretreatment as a sustainable surface modification approach towards high-strength bamboo biocomposites based on D. sinicus. Extracellular enzyme activity analysis suggested that the lignin oxidative enzyme and pectinase secreted by the white-rot fungus T. versicolor achieved higher reaction than the hydrolytic enzymes throughout the pretreatment. Chemical structure analysis revealed that lignin and hemicellulose were partially depolymerised and/or removed during the pretreatment, leading to a relatively higher cellulose content in D. sinicus. The analysis of physical property and microstructure suggested that the surface wettability and porosity of pretreated D. sinicus were significantly improved, facilitating the spreading and penetration of adhesive resins, which subsequently contributed to the superior interfacial bonding of the biocomposites. The tensile strength of the biocomposites increased from 195.8 MPa to 245.8 MPa and the bonding strength increased from 4.9 MPa to 6.3 MPa after the pretreatment, which were 1.26 times and 1.28 times those of the untreated biocomposite respectively. The results proved that the fungal and enzymatic pretreatment is a promising, eco-friendly and efficient surface modification approach for the preparation of high-strength lignocellulosic biocomposites.

The functional role of N-link glycosylation in a novel cellobiohydrolase II (LsCel6A) from a white-rot fungus Lentinus sp. WR2

The functional role of N-link glycosylation in a novel cellobiohydrolase II (LsCel6A) from a white-rot fungus Lentinus sp. WR2

Enhancing Laccase and Manganese Peroxidase Activity in White-Rot Fungi: The Role of Copper, Manganese, and Lignocellulosic Substrates

Enhancing Laccase and Manganese Peroxidase Activity in White-Rot Fungi: The Role of Copper, Manganese, and Lignocellulosic Substrates

White and brown rot fungal decay resistance of epoxy composite modified with nanocellulose and tetraethoxysilane

The resistance of epoxy composite modified with nanocellulose and tetraethoxysilane (TEOS) to decay by white rot (Trametes versicolor) and brown rot (Coniophora puteana) fungi was investigated using EN 113 (1996) as the guideline. The objective of this study was to investigate the effect of TEOS as a cross-linked agent in epoxy/nanocellulose composite, and its resistance against white rot and brown rot fungi. The epoxy resin was mixed with 10 wt% nanocellulose. The other three sets were prepared the same, but with the addition of 1%, 2%, and 3% TEOS for each set. All types of epoxy composites were air dried in a mold at ambient temperature for seven days followed by oven drying at 80 °C for 30 min. The composites were oven dried at 103 °C, sterilized, and exposed to the fungi at 22 °C for 16 weeks. It was found that the use of 1% to 3% TEOS in the composite reduced the percent weight loss following decay by T. versicolor, but not in the case of C. puteana. Overall, all types of the composite in this study were classified as highly durable and durable against the T. versicolor and C. puteana respectively. The surface and structure of all types of composites were still intact after 16 weeks of exposure period.

Exploring Ganoderma lucidum: morphology, cultivation and market potential.

Ganoderma lucidum, known as the "mushroom of immortality," is a white rot fungus renowned for its medicinal properties, attributed to its bioactive compounds. Although species with similar morphological traits to G. lucidum are found across the globe, precise identification is made possible through DNA barcoding and molecular phylogenetic analysis. Global cultivation and wild harvesting of G. lucidum are both done in response to the growing market needs. Artificial cultivation is typically performed on sawdust, but other woody substrates and the wood log method are also employed. This cultivation leverages the fungus's ecological role in converting industrial and agricultural solid wastes into biomass, thereby producing functional food and potential pharmaceutical sources. The review consolidates research on various aspects of, including cultivation methods (sawdust, agricultural waste, wood logs, and submerged fermentation), and the current global market conditions.

White rot fungi to decompose organophosphorus insecticides and their relation to soil microbial load and ligninolytic enzymes

The functional and structural features of microbial load in soil are influenced by the presence of insecticides. This study examined the impact of two organophosphorus insecticides, dimethoate and parathion on the microbial load of soil. The colony count of fungi, actinomycetes, bacteria, and nitrogen fixing bacteria was reduced after insecticides application at 7 and 14 days, but at 28 days the colony count began to increase. The growth of two white rot fungi including Pleurotus sajor-caju and Phanerochaete chrysosporium was affected by parathion, which was reflected by a decrease in colony radius to 1.85±0.05 and 0.75±0.06 cm, respectively, and by dimethoate, reflected by a decrease in colony radius to 3.33±0.12 and 1.85±0.05 cm, respectively at 40 mg/L compared to colony radius at control 7.90±0.12 and 7.50±0.06 cm, respectively. The applied low concentration (10 mg/L) encouraged P. sajor-caju and P. chrysosporium to remove up to 87.7% and 81.8% of dimethoate, respectively, and 69.20 and 68.30% of parathion, respectively compared with the decomposition at high dose (40 mg/L) at 28 days. The presence of insecticides induced the production of ligninolytic enzymes lignin peroxidase, laccase, and manganase peroxidase.

Catalytic function of the laccase enzyme in response to chlorpyrifos and 2,4-dichlorophenoxyacetic acid: behavior in controlled and simulated environments.

Enzymes secreted by white-rot fungi, such as laccase, offer a promising solution for treating xenobiotic compounds dangerous to the environment and human health. This study aimed to perform a comprehensive analysis of the tolerance of Pleurotus pulmonarius LBM 105 and its laccase activity toward the pesticides 2,4-D and chlorpyrifos both in vitro and in silico. The fungal strain was able to grow in different concentrations of the pesticides, showing evident morphological alterations. Laccase activity and a 53kDa electromorph were present in all treatments, showing significant stability with peak activity achieved at a pH of 5.6 and within a temperature range of 50-60°C. Three laccase genes were mapped, annotated, and characterized from the genome. PplacI obtained better structural validation and affinity energy of - 5.05 and - 7.65kcalmol-1 with 2,4-D and chlorpyrifos, respectively. The Molecular Mechanics/Poisson-Boltzmann Surface Area analysis at 250ns confirmed the docking results, revealing the existence of stronger hydrophobic interactions between laccase and chlorpyrifos and highlighting the importance of the Phe341 residue in stabilizing both complexes. Understanding the impact of pesticides on laccase's catalytic function is key to formulating and applying future biotechnological strategies with this enzyme.

Ganoderma lucidum triterpenoids investigating their role in medicinal applications and genomic protection.

Ganoderma lucidum (GL) is a white rot fungus widely used for its pharmacological properties and health benefits. GL consists of several biological components, including polysaccharides, sterols, and triterpenoids. Triterpenoids are often found in GL in the form of lanostane-type triterpenoids with quadrilateral carbon structures. The study revealed that triterpenoids have diverse biological properties and can be categorized based on their functional groups. Triterpenoids derived from GL have shown potential medicinal applications. They can disrupt the cell cycle by inhibiting β-catenin or protein kinase C activity, leading to anti-cancer, anti-inflammatory, and anti-diabetic effects. They can also reduce the production of inflammatory cytokines, thus mitigating inflammation. Additionally, triterpenoids have been found to enhance the immune system's defenses against various health conditions. They possess antioxidant, antiparasitic, anti-hyperlipidemic, and antimicrobial activities, making them suitable for pharmaceutical applications. Furthermore, triterpenoids are believed to afford radioprotection to DNA, protecting it from radiation damage. This review focuses on the types of triterpenoids isolated from GL, their synthesis pathways, and their chemical structures. Additionally, it highlights the pharmacological characteristics of triterpenoids derived from GL, emphasizing their significant role in various therapeutic applications and health benefits for both humans and animals.

Characterization of the Coriolopsis gallica DyP for Its Potential to Biotransform Various Fluoroquinolones.

Coriolopsis gallica (Cga) is a white-rot fungus renowned for its ability to secrete ligninolytic enzymes that are capable of oxidizing phenolic compounds. This study aimed to investigate the biochemical characteristics of a dye-decolorizing peroxidase named CgaDyP1 and test its ability to biotransform antibiotics. CgaDyP1 was cloned and heterologously expressed in Escherichia coli. We fully characterized the biochemical properties of CgaDyP1 and evaluated its dye-decolorizing potential to confirm that it belongs to the DyP class of enzymes. We also tested its fluoroquinolone antibiotic biotransformation potential for possible biotechnological applications. Alignment of the primary amino acid sequence with DyP homolog sequences showed that CgaDyP1 has high similarity with other fungal DyPs. The recombinant CgaDyP1 exhibited activity on substrates such as ABTS and 2,6-dimethoxyphenol (DMP) with optimal performance at a pH of 3, although activity at pH 2.5, pH 4, and pH5 diminished over time. Thermostability tests indicated that the enzyme remains stable at temperatures between 30 °C and 50 °C and retains 70% of its initial activity after 180 min at 50 °C. Tests on the effect of hydrogen peroxide on CgaDyP1 activity found peak activity at 0.25 mM H2O2. CgaDyP1 decolorized five industrial dyes, and kinetics data confirmed that it belongs to the DyP class of enzymes. CgaDyP1 was shown to biotransform some of the 7 recalcitrant fluoroquinolone antibiotics tested here, including levofloxacin, moxifloxacin, and norfloxacin, and thus holds potential for biotechnological applications.

Degradation of High Concentrations of Anthracene Using White-Rot Wood-Inhabiting Fungi and Investigation of Enzyme Activities

Owing to the production of lignin-modifying enzymes (LMEs), white-rot fungi (WRF) such as polypores are potent organisms in the biodegradation of xenobiotic pollutants. The nonspecific function of LMEs including laccase and manganese peroxidase (MnP), has enabled the use of WRF in biotechnological applications, particularly in bioremediation. In this study, 12 strains from nine white-rot basidiomycete genera viz., Ganoderma, Inocutis, Irpex, Lentinus, Lenzites, Oxyporus, Peniophora, Sanghuangporus, and Trametes were isolated from Iran and identified using morphological and molecular tools. The enzyme activity of laccase and manganese peroxidase that directly correlated with the biodegradation were determined, and the strains with the highest enzyme activities were evaluated for their ability to degrade 400 mg/L of anthracene over 28 days. Gas chromatography with flame ionization detector (GC-FID) revealed that four polypores viz., Trametes versicolor v21te, T. versicolor v22da, T. hirsuta, and Oxyporus sp. degraded 64%, 52%, 34%, and 20% of the anthracene, respectively. According to our analysis, the examined indigenous WRF are potentially useful candidates for the development of new mycoremediation techniques to degrade polycyclic aromatic hydrocarbons (PAHs).

Biodegradation of tri-butyl phosphate by Trametes versicolor and its application in a trickle bed reactor under non-sterile conditions

Tri-butyl phosphate (TBP) is a widely used organophosphate flame retardant. However, it is also regarded as emerging contaminant due to its various toxic effects and poor removal by conventional wastewater treatment. In present study, we investigated the degradation of TBP (10 mg/L) by the white rot fungus Trametes versicolor in both laboratory conditions and a trickle bed reactor (TBR) under non-sterile conditions. The removal yield reached 98 % after 3 days, during which the intracellular enzymatic system cytochrome P450 was involved. Four transformation products (TPs) were identified, namely dibutyl 3-hydroxybutyl phosphate, dibutyl phosphate, butyl 3-hydroxybutyl phosphate and butyl dihydrogen phosphate, which allowed us to propose a degradation pathway where hydroxylation and hydrolysis made considerable contribution. TBP treatment in the TBR with T. versicolor immobilized on wood chips operating in sequential batch mode with 10 cycles of 3 days reached average removals higher than 93 %, demonstrating the potential for practical application. Despite similar removal rates in heat-killed and abiotic controls (89 % and 97 %, respectively), global mass balance analysis indicated 86 %, 64 %, and 86 % removal by degradation in the fungal, heat-killed, and abiotic controls, respectively. Analysis of the microbial assemblage in solid phase suggested that the established bacterial populations displayed a synergistic effect with immobilized fungus. This study is the first to report on TBP degradation by T. versicolor in a TBR under non-sterile conditions, suggesting that this method could be a viable option for large-scale environmental applications.

Among-family variations of wood-color parameters, decay resistance, total phenol, and total flavanol content in the heartwood of the third-generation Acacia mangium in Indonesia

Abstract To evaluate the inheritance of natural durability of Acacia mangium Willd., wood-color parameters (Y [lightness], x [red to green], and y [yellow to blue]), mass loss by a white-rot fungus (Trametes versicolor) and brown-rot fungus (Fomitopsis palustris), and three different extracts (methanol extract, total phenol, and total flavanol content) were measured using the inner and outer heartwood of 10-year-old trees from 20 half-sib families in the third-generation A. mangium in Indonesia. The broad-sense heritability (H 2) values were moderate to high for the wood-color parameters and mass loss by white- and brown-rot fungi (H 2 = 0.210–0.851) and low to moderate for three different extracts (H 2 = 0.000–0.576). Significant negative phenotypic correlations were found between the three different extracts and mass loss by T. versicolor and F. palustris. In addition, negative correlations were found between the wood-color parameters and three different extracts. Similar results were found between the total phenol content and y and between the total flavanol content and Y in genetic correlations. Therefore, A. mangium families with lower Y and y in heartwood could produce progenies with higher total phenol and total flavanol content, leading to higher natural decay resistance.