Brown Rot Fungi Research Articles

Biological Characteristics, Domesticated Cultivation Protocol, Antioxidant Activity, and Protective Effects against Cellular Oxidative Stress of an Underutilized Medicinal Mushroom: Fomitopsis palustris

Brown-rot fungus is one of the important medicinal mushrooms, which include some species within the genus Fomitopsis. This study identified wild macrofungi collected from a broad-leaved tree in Liaoning Province as Fomitopsis palustris using both morphological and molecular methods. To elucidate the potential medicinal and economic value of F. palustris, we conducted single-factor and orthogonal tests to optimize its mycelium culture conditions. Subsequently, we completed liquid culture and domestic cultivation based on these findings. Furthermore, crude polysaccharides were extracted from the cultivated fruiting bodies of F. palustris and their antioxidant activity was evaluated using chemical methods and cell-based models. The results showed that the optimal culture conditions for F. palustris mycelium were glucose as the carbon source, yeast extract powder as the nitrogen source, pH 6.0, and a temperature of 35 °C. Moreover, temperature was found to have the most significant impact on mycelial growth. The liquid strains were fermented for 6 days and then inoculated into a cultivation substrate composed of broadleaf sawdust, resulting in mature fruiting bodies in approximately 60 days. The crude polysaccharides extracted from the cultivated fruiting bodies of F. palustris (FPPs) possess in vitro scavenging abilities against DPPH radicals and OH radicals, as well as a certain ferric-reducing antioxidant power. Additionally, FPPs effectively mitigated H2O2-induced oxidative stress in RAW264.7cells by enhancing the intracellular activity of antioxidant enzymes such as SOD and CAT, scavenging excess ROS, and reducing MDA levels. This study provides preliminarily evidence of the potential medicinal and economic value of F. palustris and offers initial data for the future development and utilization of this species.

Mycelium-based biomimetic composite structures as a sustainable leather alternative

Fungi, the main destructors of bio-waste, are opening up a new field for bio-based materials that contribute to a more eco-friendly future. In the fashion industry, using mycelium as a substitute for leather seems particularly promising. However, research has not yet been able to imitate the properties of leather. To this end, the mycelium of various white rot fungi (Fomesfomentarius, Pleurotuseryngii and Trametesversicolor and, as a control, the brown rot fungus Fomitopsispinicola) was characterized. The biomimetic techno-pull approach was used to find suitable reinforcements like needle felts or woven fabrics made from regenerated cellulose fibres for the mycelium that increases tensile strength. Two methods to produce composite materials were tested: mycelial pulp grown on a liquid medium and mycelium grown directly on a reinforcement soaked with the same liquid. Overall, mechanical characteristics from purely cultured mycelium will not necessarily reflect the same characteristics of the fungus in an embedded fibre reinforcement. Nevertheless, both methods have resulted in promising materials, with F.fomentarius pulp and T.versicolor on needle felt, outperforming the tensile strength of artificial leather and Reishi™ from MycoWorks.

Improving the Decay Resistance of Wood through the Fixation of Different Nanoparticles Using Silica Aerogel.

Nowadays, the protection of wood is becoming more important with the increasing demand for durable wood, in addition to its limited accessibility. One possible way to increase the durability is the use of nanoparticles, which can be effective even with a low intake of active ingredients. However, avoiding their leaching is a challenge. A possible solution to leaching is the use of silica aerogel as a fixative. This study investigated the use of mesoporous silica aerogel against the leaching of different nanoparticles under laboratory conditions. Tests were performed involving beech (Fagus sylvatica) and Scots pine (Pinus sylvestris) sapwood, using Trametes versicolor as a white rot and Coniophora puteana as a brown rot fungus. The results show that the subsequent treatment of the wood with mesoporous silica aerogel effectively fixed the nanoparticles in wood. The durability of the samples without aerogel significantly decreased as a result of leaching, whereas the resistance of the samples treated with aerogel decreased only slightly. However, the silica aerogel modification itself caused the leaching of silver nanoparticles, which is a limitation in the use of this method for the fixation of nanoparticles.

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.

Unlocking the distinctive enzymatic functions of the early plant biomass deconstructive genes in a brown rot fungus by cell-free protein expression.

Saprotrophic fungi that cause brown rot of woody biomass evolved a distinctive mechanism that relies on reactive oxygen species (ROS) to kick-start lignocellulosic polymers' deconstruction. These ROS agents are generated at incipient decay stages through a series of redox relays that shuttle electrons from fungus's central metabolism to extracellular Fenton chemistry. A list of genes has been suggested encoding the enzyme catalysts of the redox processes involved in ROS's function. However, navigating the functions of the encoded enzymes has been challenging due to the lack of a rapid method for protein synthesis. Here, we employed cell-free expression system to synthesize four redox or degradative enzymes, which were identified, by transcriptomic data, as conserved players of the ROS oxidation phase across brown rot fungal species. All four enzymes were successfully expressed and showed activities that enable confident assignment of function, namely, benzoquinone reductase (BQR), ferric reductase, α-L-arabinofuranosidase (ABF), and heme-thiolate peroxidase (HTP). Detailed analysis of their catalytic features within the context of brown rot environments allowed us to interpret their roles during ROS-driven wood decomposition. Specifically, we validated the functions of BQR as the driver redox enzyme of Fenton cycles and reconstructed its interactions with the co-occurring HTP or laccase and ABF. Taken together, this research demonstrated that the cell-free expression platform is adequate for synthesizing functional fungal enzymes and provided an alternative route for the rapid characterization of fungal proteins, escalating our understanding of the distinctive biocatalyst system for plant biomass conversion.IMPORTANCEBrown rot fungi are efficient wood decomposers in nature, and their unique degradative systems harbor untapped catalysts pursued by the biorefinery and bioremediation industries. While the use of "omics" platforms has recently uncovered the key "oxidative-hydrolytic" mechanisms that allow these fungi to attack lignocellulose, individual protein characterization is lagging behind due to the lack of a robust method for rapid synthesis of crucial fungal enzymes. This work delves into the studies of biochemical functions of brown rot enzymes using a rapid, cell-free expression platform, which allowed the successful depictions of enzymes' catalytic features, their interactions with Fenton chemistry, and their roles played during the incipient stage of brown rot when fungus sets off the reactive oxygen species for oxidative degradation. We expect this research could illuminate cell-free protein expression system's use to fulfill the increasing need for functional studies of fungal enzymes, advancing the discoveries of novel biomass-converting catalysts.

Water-Related Properties and Biological Durability of Wood-Based Composites

There is insufficient data regarding the biodegradation of wood-based composites (WBC) by wood decay fungi. This study aimed to evaluate the biological durability and water-related properties of different WBC types. Although WBC are primarily designed for dry environments, in building applications, they may face increased moisture risks due to water leakage, condensation, or humid air. The panels, including oak-pine shield parquet (OPP), oriented strand board (OSB), birch plywood (BP), particle board (PB), laminated particle board (LPB), moisture-resistant particle board (MRPB), medium density fibreboard (MDF), laminated medium density fibreboard (LMDF) and moisture resistant medium density fibreboard (MRMDF), were subjected to attack by brown rot fungus Coniphora puteana. After 16 weeks of exposure, the most resistant WBC against biodegradation were BP, moisture-resistant MDF, and laminated MDF, as they exhibited a mass loss lower than 5 %. Conversely, all other WBC types showed high susceptibility to biodegradation, with a mass loss exceeding 35 %. LMDF (8 – 51 %) and MRMDF had the lowest water absorption (WA) within 168 h (2 – 46 %), while non-treated MDF exhibited the highest WA among all composite types with 190 % water uptake. With regards to thickness swelling, all WBC types, except for LPB and MDF, demonstrated values below 20 %. The influence of adhesives (phenol-formaldehyde or melamine urea-formaldehyde) used in WBC did not show a clear impact on water-related properties orbiological durability.

Effect of Biodeterioration on Modeling Parameters of Code-Compliant Cross-Laminated Timber Lateral Connections

Abstract The effect of biodeterioration on the structural connection performance of timber for conventional framing and mass timber has been investigated recently, but there is a need for additional data as well as for the development of analytical models to utilize these data. An empirical material model (seismic analysis of wood frame shear walls) was fitted to cyclic connection test data of four species of cross-laminated timber at different levels of biodeterioration by two brown-rot fungi. These model inputs were then analyzed to account for trends between wood species and fungal species. Weak trends were most prominent for initial stiffness, intercept load, and displacement at peak force. Correlations were poor with postyield and postpeak stiffness modifiers. These relationships were consistent both as a function of time and as a function of mass loss, but additional data are needed to more accurately predict the effects. The limited relationships likely reflect the variations in fungal decay across the test members.

Filamentous Fungi as Bioremediation Agents of Industrial Effluents: A Systematic Review

The industrial sector plays a significant role in global economic growth. However, it also produces polluting effluents that must be treated to prevent environmental damage and ensure the quality of life for future generations is not compromised. Various physical, chemical, and biological methods have been employed to treat industrial effluents. Filamentous fungi, in particular, have garnered attention as effective bioremediation agents due to their ability to produce enzymes capable of degrading recalcitrant compounds, and adsorb different pollutant molecules. The novelty of the work reported herein lies in its comprehensive assessment of the research surrounding the use of white- and brown-rot fungi for removing phenolic compounds from industrial effluents. This study employs a systematic review coupled with scientometric analysis to provide insights into the evolution of this technology over time. It scrutinizes geographical distribution, identifies research gaps and trends, and highlights the most studied fungal species and their applications. A systematic review of 464 publications from 1945 to 2023 assessed the use of these fungi in removing phenolic compounds from industrial effluents. White-rot fungi were predominant (96.3%), notably Phanerochaete chrysosporium, Pleurotus ostreatus, Trametes versicolor, and Lentinula edodes. The cultures employing free cells (64.15%) stand out over those using immobilized cells, just like cultures with isolated fungi regarding systems with microbial consortia. Geographically, Italy, Spain, Greece, India, and Brazil emerged as the most prominent countries in publications related to this area during the evaluated period.

Fireballs-Like Explosive Peroxides Produced by the Brown-rot Fungus

Abstract: Fireballs are unusual and rare phenomena usually associated with thunderstorms, although sometimes they have been observed during earthquakes, volcano eruptions or in fair weather. There are still questions about their origination, features and interaction with the environment. In this work, a new model is shown to explain the formation of fireballs in fair weather from poplar cotton and peroxides produced by brown-rot fungi. Light emission is produced via thermal decomposition of 1,2- dioxetane phenylcoumarane or 1,2-dioxetane monolignol, from lignin inside the poplar fibers. The energy released during the explosive decaying of fireballs was calculated as being about 3 kilojoules for each gram. This value is the same order of magnitude as the estimated for the explosive fireballs decaying.

A New Phenolic Acid Decarboxylase from the Brown-Rot Fungus Neolentinus lepideus Natively Decarboxylates Biosourced Sinapic Acid into Canolol, a Bioactive Phenolic Compound.

Rapeseed meal (RSM) is a cheap, abundant and renewable feedstock, whose biorefinery is a current challenge for the sustainability of the oilseed sector. RSM is rich in sinapic acid (SA), a p-hydroxycinnamic acid that can be decarboxylated into canolol (2,6-dimethoxy-4-vinylphenol), a valuable bioactive compound. Microbial phenolic acid decarboxylases (PADs), mainly described for the non-oxidative decarboxylation of ferulic and p-coumaric acids, remain very poorly documented to date, for SA decarboxylation. The species Neolentinus lepideus has previously been shown to biotransform SA into canolol in vivo, but the enzyme responsible for bioconversion of the acid has never been characterized. In this study, we purified and characterized a new PAD from the canolol-overproducing strain N. lepideus BRFM15. Proteomic analysis highlighted a sole PAD-type protein sequence in the intracellular proteome of the strain. The native enzyme (NlePAD) displayed an unusual outstanding activity for decarboxylating SA (Vmax of 600 U.mg-1, kcat of 6.3 s-1 and kcat/KM of 1.6 s-1.mM-1). We showed that NlePAD (a homodimer of 2 × 22 kDa) is fully active in a pH range of 5.5-7.5 and a temperature range of 30-55 °C, with optima of pH 6-6.5 and 37-45 °C, and is highly stable at 4 °C and pH 6-8. Relative ratios of specific activities on ferulic, sinapic, p-coumaric and caffeic acids, respectively, were 100:24.9:13.4:3.9. The enzyme demonstrated in vitro effectiveness as a biocatalyst for the synthesis of canolol in aqueous medium from commercial SA, with a molar yield of 92%. Then, we developed processes to biotransform naturally-occurring SA from RSM into canolol by combining the complementary potentialities of an Aspergillus niger feruloyl esterase type-A, which is able to release free SA from the raw meal by hydrolyzing its conjugated forms, and NlePAD, in aqueous medium and mild conditions. NlePAD decarboxylation of biobased SA led to an overall yield of 1.6-3.8 mg canolol per gram of initial meal. Besides being the first characterization of a fungal PAD able to decarboxylate SA, this report shows that NlePAD is very promising as new biotechnological tool to generate biobased vinylphenols of industrial interest (especially canolol) as valuable platform chemicals for health, nutrition, cosmetics and green chemistry.

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.

Effect of co-cultivation of white and brown rot species on basidiome production, lignocelluloytic enzyme activity and dye decolourisation

The aim of this work was studying the impact of co-cultivating two mushroom species: a white (Pleurotus albidus CLA 45) and a brown rot one (Laetiporus sulphureus BAFC 205) in substrates based on poplar or pine sawdust, on their lignocellulolytic enzyme production, yield values and basidiomes properties. Laetiporus sulphureus only developed basidiome primordia, but P. albidus monoculture and co-culture in pine sawdust achieved biological efficiencies of up to 50–55 %. Co-cultivation on diverse substrates rendered varied enzyme titers. Laccase and Manganese peroxidase titers were highest in pine co-culture and P. albidus poplar monoculture, respectively. Enzymatic extracts obtained from spent poplar substrate of dual cultures displayed potential for treating non-sterile textile-coloured effluents, achieving 35 % decolourisation after 120 h. The knowledge available on the effects of co-culture of white and brown rot fungi is still limited. This study represents an initial exploration of the interaction between them within intensive cultivation conditions.

Effects of the combination of phenolic-resin impregnation and heat treatment on physical, mechanical and decay resistance of Taxodium hybrid “Zhongshanshan” wood

ABSTRACT This study aimed to evaluate the influence of cooperative modification treatments and treatment sequencing on the properties of treated fast-growing wood. Two integrated treatment methods including, impregnation with Phenol-Formaldehyde resin followed by heat treatment (PF-HT), and heat treatment antecedent to impregnation with Phenol-Formaldehyde resin (HT-PF) were applied on Taxodium hybrid “Zhongshanshan” wood. Comprehensive characterization was undertaken, investigating micro-morphology, chemical structure, mechanical properties, shrinkage and expansion properties, and decay resistance before and after treatment. Results indicated that the weight percentage gain (WPG) of the HT-PF wood exceeded that of the PF-HT wood, and the WPG of the former displayed an ascending tendency with increasing heating temperature, reaching a final difference of 10%. For instance, the modulus of elasticity of the HT-PF wood was 18% higher than that of the PF-HT wood in the bending test at a temperature of 215°C. Throughout the dynamic water adsorption test, both the hydrated water percentage and the dissolved water percentage of PF-HT wood were lower than those of PF-HT wood. After 3 months of exposure to brown-rot fungi, both HT-PF wood and PF-HT wood achieved a high level of decay resistance.

Degradation of reburied archaeological wood piles after preservative treatment for twenty years

This study investigated the degradation mechanism and microbial communities of a reburied stone-fixed wooden pile (SP) after being excavated and treated with pentachlorophenol/polyethylene glycol (PCP/PEG) preservatives for a 20-year period at the Jin Zhongdu Watergate Heritage Cultural Site. High-throughput sequencing (HTS) techniques were combined with scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectrum analysis, and quantitative chemical analyses. A foundation wooden pile (FP) forming the watergate supports, which has been in service for nearly 870 years at the site, was also examined. The results showed that preservatives still partially remained in the SP after burial. More abundant and richer microbial communities were found in the SP (including brown rot, soft rot, white rot fungi and bacteria) due to the hydrophilic PEG providing more favorable habitats for microbial. Therefore, it was indicated that the PCP had gradually lost its antibacterial function. Although brown rot fungi had not been detected using HTS, typical morphological characteristics were observed in the FP using SEM, thereby the characteristics of brown rot fungi were the results of previous decay. The absence of brown rot may have been attributed the competition among wood rot fungi.

Effects of physicochemical characteristics on natural durability of eucalypts woods to wood-decaying fungi

This study aimed to relate the biological resistance of seven eucalypt woods to wood-decaying fungi with physicochemical characteristics of wood. Two 12-year-old trees per species were randomly sampled, removing disks at 0 (base), diameter to breast height - DBH, 25, 50, 75, and 100% of the commercial height to determine the wood specific gravity. One basal log of 2.20 m of each wooden species was obtained for chemical analysis and biological tests with brown and white rot fungi (Gleophyllum trabeum, Rhodonia placenta, and Trametes versicolor). For these tests, wood samples were taken in two positions in the radial direction of the trunk in the pith-bark direction (median heartwood and transition region; containing heartwood and sapwood), and the relation between wood natural resistance and physicochemical characteristics was established. Wood specific gravity ranged of 0.51 g cm−3 to 0.73 g cm−3, total lignin of 27.34–32.18%, and holocellulose of 53.39–66.18, not being influenced by pith-bark direction. The extractive and ash contents were affected by the pith-bark direction, in which, in general, the transition region exhibited the highest values contents. The extractive showed a negative relation (−0.67) regarding the loss of mass caused by the fungus Rhodonia placenta. For the holocellulose content, it showed positive relations (0.61; 0.54) to the degradation by Rhodonia placenta and Gleophyllum trabeum, respectively. Independently of the analyzed wood and tested fungus, the median heartwood region was more resistant to wood decay fungi than the transition region.

Biodecolorization and biotransformation of methylene blue using mixed cultures of brown-rot fungus Daedalea dickinsii and filamentous fungus Aspergillus oryzae: identification of metabolites and degradation pathway

This study aimed to examine biodecolorization and biotransformation of methylene blue (MB) using mixed cultures of brown-rot fungus Daedalea dickinsii and filamentous fungus Aspergillus oryzae.

Treatment of Delonix regia wood with castor oil (Ricinus communis) protects it against white and brown rot fungi

This study was aimed at assessing the resistance of Delonix regia wood treated with an eco-friendly bio preservative exploring castor (Ricinus communis) seed oil identified as a promising candidate for wood antifungal treatment, attributed to its documented antimicrobial properties. Sixty wood block samples of conditioned Delonix regia were treated with five different concentration levels (0 %, 25 %, 50 %, 75 % and 100 %) of formulated fungicides prepared from Sohxlet extracted oil of castor seeds and the untreated wood samples served as the control. The wood blocks were exposed to Pleurotus ostreatus (white rot fungi) and Sclerotium rolfsii (Brown rot fungi) for 14 weeks and parameters including preservative absorption, oil yield, and weight loss of the wood samples subjected to treatment were assessed. Using Analysis of variance (ANOVA) to analyze the data obtained, the mean oil yield of seeds of Ricinus communis extracted was 37.75%. The100% concentration level had the best performance with the highest absorption of 92.68 (kg/m3) while the least absorption (69.96 kg/m3) was recorded for the 25% concentration except for the control (0%) which was 118.60kg/m3. Statistically significant variations in weight loss were observed across different concentration levels, with a significance level of p < 0.05 and it ranged from 35.02 -31.42(%) for white rot while it ranged from 42.32 to 31.98(%) for brown rot apart from the control which was recorded to be 38.25% and 45.28% respectively. It can therefore be established that Delonix regia wood can be preserved with Ricinus communis seed oil extract against white rot and brown rot fungi.

Isolation, Screening, Identification, and Assessment of Laccase-Producing Fungi Isolated From Different Environmental Samples

ABSTRACT: One of the extracellular enzymes involved in ligninolytic is lacasse, secreted by white and brown rot fungus. The class of blue copper proteins that includes laccases consists of N-glycosylated multicopper oxidases. Ascomycetes, Deuteromycetes, and Basidiomycetes are all fungi that contain laccase; many of these are white-rot fungi that break down lignin. Due to their wide range of substrate specificity, laccases have been the focus of extensive research over the past few decades. Their latest applications include anything from the textile pulp and paper industries to culinary applications and bioremediation techniques. Laccases are also used in organic synthesis, where phenols and amines are common substrates. Dimers and oligomers are produced due to the coupling of reactive radical intermediates in these reactions. The current investigation gathered 50 white rot fungi, and the most incredible laccase-producing organisms in submerged fermentation were looked into. Ten of the 21 cultures displayed a reddish-brown color zone. Of these ten isolates (PTD 19, PTD 4, PP2J15, LKT 34, ITC 1, NRL 7, GOJ 7, PTD2, PP2J, and PKT12), only PP2J15 and GOJ 7 displayed the most reddish-brown color zone. The isolation of white rot fungus, their molecular characterization, and testing for laccase production are all covered in this Paper. Talaromyces verruculosus and Cladosporium cladosporioides were identified as the PP2J15 and GOJ 7 strains based on sequence comparison and phylogenetic analysis with reference taxa.

Screening of Fungal Isolates for Biodegradation Potentials of Low-Density Polyethylene from Selected Dumpsites

Polyethylene is the most commonly used synthetic plastic and poorly degraded in natural environments. This study was designed to evaluate biodegradation potentials of low-density polyethylene by fugal isolates from Station Market, Kaduna State, Nigeria. Soil samples were collected at a depth of 20cm using a sterilized hand towel and taken to microbiology laboratory, Kaduna State University. Fungi were isolated and each colony was repeatedly sub-cultured on freshly prepared SDA to obtain pure isolates. Pure separated single colonies were maintained on sterile slants at 4˚C for further investigation. Low-density polyethylene (LDPE) sheets were cut into bits and immersed in xylene and boiled for 15 minutes to dissolve and crushed. The LDPE powder was added to a mineral salt medium (MSM) containing salts in 1liter of distilled water after which the fungal isolates were introduced. Scanning electron microscopy and Fourier- Transform Infrared Spectroscopy (FTIR) analysis were used to determine the changes in the polymer bond of LDPE sheet after the biodegradation. The findings shows that Aspergillus niger, Aspergillus flavus, Brown rot and White rot fungi showed 21.1%, 16.1%, 17.6%, and 18.3% reductions in the polyethylene discs after incubation respective. Therefore, the study concludes that fungal species play a significant role in the degradation of LDPE and can be used in future studies for the degradation of complex plastic materials. Finally, the study recommends that Aspergillus niger and Aspergillus falvus be considered as potential candidates to degrade LDPE.

Comparative decay resistance of plantation-grown and naturally-grown teak wood (Tectona grandis L.f.)

Teak (Tectona grandis L.f.) is one of the most popular tropical timber species for its natural durability. The sapwood, the outer, middle, and inner heartwood, and the pith of plantation-grown teak in Indonesia and naturally grown teak in Myanmar were tested for decay resistance (a major component of natural durability), applying an accelerated decay test according to JIS Z 2101 (1994), and using a white rot fungus (Trametes versicolor) and a brown rot fungus (Fomitopsis palustris). Wood blocks 20 × 20 × 10 mm in size were cut from discs across the radius of the stem. The percentage mass loss in each block caused by decay was obtained after 12 weeks of incubation with these fungi. Mean mass losses due to T. versicolor were respectively as follows for plantation-grown, naturally-grown (No. 1), and naturally-grown (No. 2) teak: sapwood 21.4%, 7.1%, “no data”; outer heartwood 0.6%, 3.6%, 6.6%; middle heartwood 2.3%, 6.5%, 5.7%; inner heartwood 10.3%, 9.6%, 6.0%; pith 13.0%, 15.3%, 8.2%. Losses due to F. palustris were, respectively: sapwood 7.5%, 3.0%, 7.5%; outer heartwood 0.0%, 2.5%, 2.7%; middle heartwood 0.0%, 2.2%, 2.3%; inner heartwood 4.9%, 2.0%, 3.4%; pith 13.6%, 8.4%, 8.0%. Durability was classified with reference to Osborne (1970), based on the mean percentage weight loss of heartwood caused by fungal decay. Only the outer and middle heartwood were generally durable in both plantation-grown and naturally grown teak specimens. The inner heartwood was moderately durable, but pith durability was low. No clear differences in decay resistance were found between plantation-grown and naturally-grown teak.