White Rot Research Articles

Effect of dissolved oxygen on the degradation activity and consumption capacity of white-rot fungi

In recent decades, bioremediation using white rot fungi (WRF) has become an attractive alternative for the removal of xenobiotics from water. However, WRF are aerobic microorganisms whose degradative capacity may be reduced when operating in oxygen-restricted environments. This work determines the limiting dissolved oxygen level of Trametes versicolor in terms of degradation of two target micropollutants: bentazon and tributyl phosphate. When the dissolved oxygen concentration was set below 15 % saturation (1.3 mg O2·L−1), the results revealed a considerable decrease in degradation capacity and laccase synthesis. Hence, 15 % dissolved oxygen was established as a reference value of aerobic conditions to assess dissolved oxygen profiles in both a rotating drum bioreactor (RDB) and a fixed-bed bioreactor (FBB). Restrictive oxygen conditions were achieved after an operating period of 24 h in the RDB and an empty bed contact time of 44 min in the FBB. In addition, growth kinetics on Q. ilex wood and organic matter removal (in terms of COD) were studied, obtaining 0.059 mg ergosterol·g wood DW−1·day−1 and 16.23 mg O2·L−1·h−1, respectively. Therefore, T. versicolor has demonstrated a remarkable ability to assimilate complex carbon sources and a high micropollutant degradation activity, especially when operating in non-limiting oxygen regimes.

Insights into the Ecological Diversification of the Hymenochaetales based on Comparative Genomics and Phylogenomics With an Emphasis on Coltricia.

To elucidate the genomic traits of ecological diversification in the Hymenochaetales, we sequenced 15 new genomes, with attention to ectomycorrhizal (EcM) Coltricia species. Together with published data, 32 genomes, including 31 Hymenochaetales and one outgroup, were comparatively analyzed in total. Compared with those of parasitic and saprophytic members, EcM species have significantly reduced number of plant cell wall degrading enzyme genes, and expanded transposable elements, genome sizes, small secreted proteins, and secreted proteases. EcM species still retain some of secreted carbohydrate-active enzymes (CAZymes) and have lost the key secreted CAZymes to degrade lignin and cellulose, while possess a strong capacity to degrade a microbial cell wall containing chitin and peptidoglycan. There were no significant differences in secreted CAZymes between fungi growing on gymnosperms and angiosperms, suggesting that the secreted CAZymes in the Hymenochaetales evolved before differentiation of host trees into gymnosperms and angiosperms. Nevertheless, parasitic and saprophytic species of the Hymenochaetales are very similar in many genome features, which reflect their close phylogenetic relationships both being white rot fungi. Phylogenomic and molecular clock analyses showed that the EcM genus Coltricia formed a clade located at the base of the Hymenochaetaceae and divergence time later than saprophytic species. And Coltricia remains one to two genes of AA2 family. These indicate that the ancestors of Coltricia appear to have originated from saprophytic ancestor with the ability to cause a white rot. This study provides new genomic data for EcM species and insights into the ecological diversification within the Hymenochaetales based on comparative genomics and phylogenomics analyses.

Mechanical properties of structural particleboard and termite and decay resistance

The mechanical properties and termite and decay resistance performance of wood-based panel used in wooden houses were evaluated. The physical and mechanical properties, along with the resistance levels, of commonly used wood-based panels, including oriented strand board, structural particleboard, and particleboard for use in interior, were compared. The structural particleboard complied with the physical, mechanical, and formaldehyde emission standards of the International Organization for Standardization and Japanese Industrial Standard, surpassing the requirements for oriented strand board. The structural particleboard exhibited excellent water resistance and a consistent performance. Decay tests classified the particleboard and structural particleboard as “Resistant,” with mass losses of 7.82 to 12.72% (white rot) and 14.69 to 16.55% (brown rot). Pine (Pinus densiflora) and oriented strand board exhibited no decay resistance, with mass losses exceeding 45%. The particleboard and structural particleboard demonstrated superior termite resistance, resulting in 100% termite mortality in three days without chemical treatment. The structural particleboard exhibited excellent water, decay, and termite resistance, which can be an advantage in wooden-house construction in terms of maintenance.

Role of White Rot Fungi in Industrial Wastewater Treatment: A Review

White Rot Fungi (WRF) are a class of microorganisms widely understood for their ability to breakdown an extensive range of pollutants generally found in industrial wastewater. This specific literature review centers on the abilities of the White Rot Fungi to treat industrial wastewater, analysis of the biodegradation mechanism, future applications, and scaling up for practical implementation. WRF usually carry out the degradation process with ligninolytic enzyme by targeting complex industrial pollutants, such as aromatic hydrocarbons, dyes, pharmaceuticals, and products of personal care. The unique enzymatic system of WRF converts the complex and harmful industrial pollutants into harmless end and byproducts, thus minimizing the impact on the environment and ecosystem. This review paper also discusses the potential applications of WRF, such as bioremediation, biosorption, and co-culturing with bacteria to enhance the pollutants removal efficiency of already functional wastewater treatment plants. However, there are still challenges in scaling up WRF-based treatment facilities due to factors such as the optimization of conditions and processes of already functional conventional wastewater treatment plants, cost effectiveness, and design modifications of treatment facilities. Conclusively, WRF fungi can play an important role in degrading complex organic and inorganic pollutants specifically, which are not usually treated by conventional wastewater treatment plants.

Study of new biocontrol bacterial agent Bacillus velezensis S41L against Rosellinia necatrix

White root rot in woody plants is mainly caused by the necrotrophic phytopathogenic fungus Rosellinia necatrix. In this study, we isolate antagonistic bacteria from rhizospheric soil from asymptomatic pear trees infested with white root rot. Furthermore, we isolated 40 bacterial strains and screened them for antagonistic activity against R. necatrix. Then, we selected antagonists that retarded pathogen growth for >30 days. Finally, the strain that exhibited >80 % inhibitory activity against all R. necatrix strains (Korean Agricultural Culture Collection 40446, 40445, 40447, and 40168), demonstrating its effectiveness in controlling this pathogen prevalent in Korean pear and apple orchards, was selected for further experiments. Strain S41L (OP349111) showed the most potent growth-inhibitory activity against the tested phytopathogens. Microbiological and 16S rRNA gene sequencing analyses revealed that the bacterial isolate belonged to the Bacillus genus and had 100 % nucleotide sequence similarity with Bacillus velezensis in GenBank. This strain also harbored antibiotic biosynthesis genes and possessed plant growth-promoting traits such as phosphate solubilization, indole-3-acetic acid, and siderophore production.

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.

Two Bacterial Bioagents Boost Onion Response to Stromatinia cepivora and Promote Growth and Yield via Enhancing the Antioxidant Defense System and Auxin Production

White rot, caused by Stromatinia cepivora (Anamorph: Sclerotium cepivorum Berk), is a serious soil-borne disease of the onion that restricts its cultivation and production worldwide. Herein, we isolated and characterized a plant growth-promoting rhizobacterium Stenotrophomonas maltophilia from healthy onion roots and an endophytic bacterium Serratia liquefaciens from healthy bean leaves. Both isolates showed strong fungistatic activity against S. cepivora using the dual culture and culture filtrate methods. This effect might be due to the presence of several volatile compounds, especially menthol in both culture filtrates as shown with a GC-MS analysis. Additionally, the root drench application of cell-free culture filtrates of S. maltophilia and S. liquefaciens significantly reduced the incidence and severity of white rot disease on treated onion plants, which was associated with the activation of both enzymatic (POX and PPO) and non-enzymatic (phenolics and flavonoids) antioxidant defense machineries of S. cepivora-infected onion plants. Moreover, the culture filtrates of both bacterial bioagents remarkably enhanced the growth (as expressed by root length, plant height, and number of leaves) and yield parameters (as indicated by bulb circumference, fresh weight of the bulb, and bulb yield per plot) of treated onion plants under field conditions during two successive seasons (2020/2021 and 2021/2022). This might be because of a reduced disease severity and/or the accumulation of the main auxin, indole-3-acetic acid (IAA), and its precursor, the amino acid tryptophan. Our findings suggest that both bioagents might be utilized as eco-friendly alternative control measures to reduce the utilization of chemical fungicides entirely or partially for the safer production of onion in S. cepivora-infested soils.

Identification of Fusarium Basal Rot Pathogens of Onion and Evaluation of Fungicides against the Pathogens

Onion (Allium cepa L.) is an economically important vegetable crop worldwide. However, various fungal diseases, including Fusarium basal rot (FBR), neck rot, and white rot, reduce onion production or bulb storage life. FBR caused by Fusarium species is among the most destructive onion diseases. In this study, we identified Fusarium species associated with FBR in Jeolla and Gyeongsang Provinces in South Korea and evaluated fungicides against the pathogens. Our morphological and molecular analyses showed that FBR in onions is associated with Fusarium commune, Fusarium oxysporum, and Fusarium proliferatum. We selected seven fungicides (fludioxonil, hexaconazole, mandestrobin, penthiopyrad, prochloraz-manganese, pydiflumetofen, and tebuconazole) and evaluated their inhibitory effects on mycelial growth of the pathogens at three different concentrations (0.01, 0.1, and 1 mg/mL). We found that prochloraz-manganese was highly effective, inhibiting 100% of the mycelial growth of the pathogens at all concentrations, followed by tebuconazole. Fludioxonil showed < 50% inhibition at 1 mg/mL for the tested isolates.

Species diversity of pathogenic wood-rotting fungi (Agaricomycetes, Basidiomycota) in China

ABSTRACT Wood-rotting basidiomycetes have been investigated in the Chinese forest ecosystem for the past 30 years. Two hundred and five pathogenic wood-decayers belonging to 9 orders, 30 families, and 74 genera have been found in Chinese native forests, plantations, and gardens. Seventy-two species (accounting for 35% of the total pathogenic species) are reported as pathogenic fungi in China for the first time. Among these pathogens, 184 species are polypores, nine are corticioid fungi, eight are agarics and five are hydnoid basidiomycetes. One hundred and seventy-seven species (accounting for 86%) cause white rot, while 28 species (accounting for 14%) result in brown rot; 157 species grow on angiosperm trees (accounting for 76.5%) and 44 species occur on gymnosperm trees (accounting for 21.5%), only four species inhabit both angiosperms and gymnosperms (accounting for 2%); 95 species are distributed in boreal to temperate forests and 110 in subtropical to tropical forests. In addition, 17 species, including Fomitopsis pinicola, Heterobasidion parviporum, and Phellinidium weirii etc. which were previously treated as pathogenic species in China, do not occur in China according to recent studies. In this paper, the host(s), type of forest, rot type, and distribution of each pathogenic species in China are given.

RGO'nun P. Chrysosporium'un Mikrobiyal Aktivitesi Üzerindeki Etkisinin İncelenmesiyle Grafen Bazlı Malzemelerin Potansiyel Çevresel Risklerinin Değerlendirilmesi.

Graphene has been used in various applications in many fields. In recent years, its annual output has reached one hundred tons. Graphene has shown great potential in analytics, medicine, electronics, energy, agriculture, and environmental remediation. With increasing applications and production, the environmental risks and hazards of graphene have increased public concern. It was a key issue in environmental risk assessments of graphene materials. Microbial degradation of graphene and graphene oxide and its degradation by fungi in the environment have been previously studied. However, reduced graphene oxide (rGO) was difficult to degrade by fungi, and there were limited studies on this subject. In this study, the white rot fungus Phanerochaete chrysosporium was incubated with the culture system rGO for one week. The independent variables of microorganism concentration, pH, and rGO concentration were analyzed with the Box Behnken statistical method using response surface methodology. The potential environmental risks of graphene-based materials were assessed by examining the effect of rGO on the microbial activity of P. chrysosporium. The results revealed that rGO inhibited microbial activity during incubation and acted as an inhibitor in the medium. In addition, pH was found to be effective in inhibiting the environment, while microbial activity decreased at low pH. Moreover, P.chrysosporium was thought to degrade the oxygen groups on the rGO surface due to its decomposition ability. To test the environmental impact of graphene-based materials in general, it was aimed at unraveling the structure-activity relationships of the fungus P. chrysosporium.

O77 (not presented) Conversion of lignocellulosic biomass into valuable feed for ruminants using white rot fungi

O77 (not presented) Conversion of lignocellulosic biomass into valuable feed for ruminants using white rot fungi

White Rot of Korean Wild Chive Caused by Stromatinia cepivora

In May 2020, we surveyed disease occurrence on vegetables grown in Seosan area, Korea. During the disease survey, white rot symptoms were observed in Korean wild chive (&lt;i&gt;Allium monanthum&lt;/i&gt;) plants growing in fields. The symptoms occurred mainly in the seed bulb-producing fields of the crop. The above ground parts of the diseased plants displayed premature yellowing and dying of older leaves and stunting of the plants. The bulbs and roots of the diseased plants turned black and rotted. The disease occurred in a range of 1–60% in four of the eight fields surveyed. Three isolates of &lt;i&gt;Sclerotium&lt;/i&gt; sp. were obtained from the bulb lesions of diseased plants. All isolates were identified as &lt;i&gt;Stromatinia cepivora&lt;/i&gt; based on the morphological characteristics and phylogenetic analysis. Pathogenicity of the isolates on Korean wild chive was confirmed by artificial inoculation test. The lesions induced by the inoculation test were similar to those observed in the investigated fields. This is the first report of &lt;i&gt;S. cepivora&lt;/i&gt; causing white rot in Korean wild chive.

Preservatve Potentials of Datura metel Seed Oil on Triplochiton scleroxylon Wood (Schumann)against Fungal Attack

This experiment was carried out to evaluate the potential of extracted Datura metel seed oil as a bio wood preservative against fungi attack as reports have shown bio-preservatives to be toxic free and environmentally friendly. The oil was extracted from the seed by Soxhlet apparatus using N-Hexane and ethanol solvents and using volume-to-volume method of dilution kerosene (at 50%) was added to increase its quantity thereafter. The phytochemical screening of the seed of Datura metel revealed the presence of tannins, alkaloids, flavonoids, saponins and phenols. Wood samples of Triplochiton sceleroxylon were cut to 20 × 20 × 60mm and the dimensioned wood samples were soaked for 72 hours in the seed oil extract hence preservative absorption rate and percentage weight loss of wood was determined on exposure to a purely cultured Sclerotium rolfsil (brown rot fungi) and Pleurotus ostreatus(white rot fungi). Data obtained were subjected to analysis of variance at α0.05 and the results showed the highest value of mean weight loss of 18.29% while the samples exposed to brown rot fungi has a mean value of 14.12% and white rot a lowest mean value of 12.72%. The highest absorption was observed to be 92.73 kg/m at 100 % concentration level of D,metel extract. Based on the results obtained, the seed-oil extracts of Datura metel have the potential of being an effective wood preservative.

AKTIVITAS ANTIJAMUR PELAPUK KAYU NANOPARTIKEL KITOSAN-EKSTRAK N-HEKSAN DAGING BUAH KAYU GADIS (Cinnamomum parthenoxylon)

This study aims to synthesize chitosan nanoparticles - n-hexane extract of Cinnamomum parthenoxylon (CP) fruit using the ionic gelation method, to characterize them, and to determine their antifungal activity against the wood-rotting fungi Trametes versicolor and Fomitopsis palustris. Chitosan-CP extract nanoparticles were formulated with chitosan:Na-TPP:CP extract ratio of 1:1:0.5. Particle size and polydispersity index were determined using a particle size analyzer (PSA), and particles morphology was observed using a scanning electron microscope (SEM), and antifungal activity was measured using agar media. The results revealed that the average size of chitosan nanoparticles (base) was 276.9 nm, while the average size of chitosan-CP extract nanoparticles was 807.6 nm. The polydispersity index (PI) of both nanoparticles was greater than 0.7. Observations of the nanoparticles' morphology revealed that aggregation/agglomeration formed in the resulting particles. Both nanoparticles chitosan (base) and chitosan-CP extract inhibited the growth of white rot fungi (T. versicolor) more than brown rot fungi (F. palustris), as measured by the inhibitory zone.

The growth of white rot fungi in the biodelignification process of sawdust of Sengon

Sengon-wood sawdust (SWD) is the waste generated from the sawmill industry and can be utilized as making ethanol and pulp because the waste contains high fiber. The material is processed through biodelignification by white rot fungi. The purpose of this study was to observe the growth of Phanerochaete chrysosporium (PC) and Trametes versicolor (TV) in the biodelignification process of wood sawdust Sengon with a single culture and mixed culture with the growth of white rot fungi macroscopic (spread of the mycelium, the color powder, texture powder) and microscopic (surface properties and thickness of mycelium) using Flat Digital Microscope and SEM (Scanning Electron Microscope). This research method used a Completely Randomized Design (CRD) with one factor: the type of white rot fungi; J1: Phanerochaete chrysosporium, J2: Trametes versicolor), J3: a mixture of PC + TV, with each 3 repetitions. The results showed that The growth of single-culture Phanerochaete chrysosporium in the process of biodelignification of sengon sawdust (SWD) is best compared to single-culture TV and co-culture PC+TV. The results of this study provide information on the selection of types of fungi that have the potential to release lignin, which facilitates the process of pulping or alcoholic fermentation for biofuels.

Plant Physiological Assessments on Promising New HLB-Tolerant Citrus Rootstocks after Inoculation with the Phytopathogenic Ascomycete Rosellinia necatrix

Citriculture is considered the most important fruit industry and involves the cultivation of several fruit varieties, which are susceptible to many plant pathogens. In this sense, soil-borne pathogenic fungi, such Rosellinia necatrix, threaten citrus fruit production worldwide because they can cause fruit loss. Therefore, we assayed the physiological reaction of novel citrus rootstocks against white root rot disease during long-term management. Data from above-ground symptoms and chlorophyll content were periodically obtained during the experimental process. In addition, plant leaf area and percentage of biomass reduction were determined for each rootstock when the experiment finished. The behavior of the inoculated tolerant rootstocks was as follows: the lowest symptom rate of SAUDPC was achieved by B11R5T25 and N40R3T25; AMB+CZO manifested the highest disease incidence; B11R5T25 and A+VOLK × Orange 19-11-8 displayed the highest and the lowest chlorophyll content, respectively; AMB+CZO and A+VOLK × Orange 19-11-8 showed the highest biomass reduction, and the lowest was detected in B11R5T25 and N40R2T19; concerning the leaf area, N40R1T18, N40R3T25 and N40R2T19 showed the lowest response, and 2247 × 2075-01-2 achieved the highest rate. In summary, B11R5T25 and N40R3T25 displayed the lowest disease rate.

Energy value of silver fir (Abies alba) and Norway spruce (Picea abies) wood depending on the degree of its decomposition by selected fungal species

Negative environmental impacts related to climate change and social pressure to raise the rotation age of forests contribute to the quality deterioration of harvested wood, including its decomposition by fungi. This paper presents the results of laboratory experiments investigating the decomposition of Norway spruce (Abies alba) and silver fir (Picea abies) wood by selected species of decay fungi: Hericium flagellum and Bondarzewia mesenterica (causing white rot) as well as Rhodofomes roseus (causing brown rot). The decay process affects wood density, elemental composition, net calorific value, as well as the amount and price of the energy contained in the wood. Wood density was measured conventionally using an electronic caliper and laboratory balance. Energy parameters were determined using elemental analyzer and combustion calorimeter. Wood decay was found to adversely affect energy content per unit of wood at a given volume, thus leading to higher prices per unit of energy. Over the 120 days of the experiment, wood parameters were not affected considerably by Hericium flagellum or Bondarzewia mesenterica. Of the three examined fungal species, Rhodofomes roseus caused the highest weight loss of wood and the greatest decrease in its oven-dry density (spruce - a decrease from 409 to 214 kg m−3; fir - a decrease from 420 to 306 kg m−3), unfavorably reducing energy content per 1 m3 of wood (spruce – decrease by 3.8 GJ m−3; fir – decrease by 2.3 GJ m−3) and raising the unit price of energy.

Fine-scale cation dynamics and control by Rhodonia placenta and Pleurotus ostreatus during wood decay

Fungi are the primary decomposers of wood across the globe. They redistribute the vast pool of wood carbon to other parts of the carbon cycle using mechanisms that also have intriguing potential in bioconversion and biotechnology applications. To make a living in the relatively sparse microenvironment of wood, these filamentous fungi must import many of their needs, including cations. Understanding the timing of cation import can help us validate the functions of cations in wood decay and create a clearer understanding of these complex wood degradation mechanisms. In this study, we resolved cation timing dynamics across space for two fungi (brown rot fungus Rhodonia placenta and white rot fungus Pleurotus ostreatus) using a wood wafer system. We found some expected patterns of the cation dynamics for both fungi, and a clear role for iron at the early stages of brown rot decay. On the other hand, the lack of an increase in manganese during initial white rot decay was surprising. Unexpectedly, we also saw a spike in copper during early brown rot decay that demands more investigation as a potential player in the brown rot mechanism.

Functional fungal pellets self-immobilized by mycelium fragments of Irpex lacteus WRF-IL for efficient degradation of sulfamethazine as the sole carbon source

In order to achieve an efficient microbial material with dual functions of self-immobilization and sulfamethazine (SMZ) degradation, this study explored the pelletization technique utilizing mycelium fragments of Irpex lacteus WRF-IL and systematically examined the pellets formation conditions and degradation capability. The Box-Behnken design results demonstrated that pure mycelium fragments, broken by frosted glass beads, could be rapidly self-immobilized to form white rot mycelial pellets (WRMPs) within 24 h, serving as the pelleting core. These WRMPs could completely remove SMZ as the sole carbon source within 20 h. The addition of sucrose expedited this process, achieving complete removal within only 14 h. Kinetic analysis showed that WRMPs could potentially remove SMZ at higher concentrations (>25 mg/L). Biodegradation was the primary pathway of SMZ removal. Seven intermediates were identified by QTOF LC/MS, and three transformation pathways initiated by SO2 overflow, molecular rearrangement, and aniline moiety oxidation were deduced.

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.