Chemical polymorphism and antifungal activity of essential oils from leaves of different provenances of indigenous cinnamon (Cinnamomum osmophloeum)

The essential oils isolated from nine geographical provenances of indigenous cinnamon (Cinnamomum osmophloeum Kaneh.) leaves were examined by GC-MS and their chemical constituents were compared. According to GC-MS and cluster analyses the leaf essential oils of the nine provenances and their relative contents were classified into six chemotypes-cinnamaldehyde type, cinnamaldehyde/cinnamyl acetate type, cinnamyl acetate type, linalool type, camphor type and mixed type. In addition, the antifungal activities of leaf essential oils and their constituents from six chemotypes of indigenous cinnamon were investigated in this study. Results from the antifungal tests demonstrated that the leaf essential oils of cinnamaldehyde type and cinnamaldehyde/cinnamyl acetate type had an excellent inhibitory effect against white-rot fungi, Trametes versicolor and Lenzites betulina and brown-rot fungus Laetiporus sulphureus. The antifungal indices of leaf essential oils from these two chemotypes at the level of 200 micro/ml against T. versicolor, L. betulina and L. sulphureus were all 100%. Among them, the IC(50) (50% of inhibitory concentrations) value of the essential oil of cinnamaldehyde type leaf against L. sulphureus was 52-59microg/ml. Cinnamaldehyde possessed the strongest antifungal activities in comparison with other constituents of the essential oils from cinnamaldehyde type leaf, at the level of 100microg/ml its antifungal indices against T. versicolor, L. betulina and L. sulphureus were 100%. The IC50 values of cinnamaldehyde against T. versicolor, L. betulina and L. sulphureus were 73, 74 and 73microg/ml, respectively.     

Antifungal activity of cinnamaldehyde and eugenol congeners against wood-rot fungi

In this study, the antifungal activities of cinnamaldehyde and eugenol congeners against white-rot fungus Lenzites betulina and brown-rot fungus Laetiporus sulphureus were evaluated and the relationships between the antifungal activity and the chemical structures were also examined. Results from antifungal tests revealed that cinnamaldehyde, alpha-methyl cinnamaldehyde, (E)-2-methylcinnamic acid, eugenol and isoeugenol exhibited strong antifungal activity against all fungi tested. Results derived from the chemical structure-antifungal activity relationship study suggested that compounds with an aldehyde group or an acid group, a conjugated double bond and a length of CH chain outside the ring affect their antifungal properties. Furthermore, the presence of the methyl moiety in the ortho position may have a considerable influence on the inhibitory action against L. betulina and L. sulphureus. In addition, the lipophilicity may play, in part, a crucial role in determining the toxicity of phenylpropenes.     

Synergistic effects of cinnamaldehyde in combination with eugenol against wood decay fungi

The combined effects of using cinnamaldehyde with catechin, quercetin or eugenol against wood decay fungi were examined by comparing their isoeffective concentrations to that of individual compound. Among all combinations, cinnamaldehyde with eugenol revealed the strongest synergy against Laetiporus sulphureus. The synergism was due to the interference of fungal cell wall synthesis and cell wall destruction plus radical scavenging effect. Results also suggested that antioxidant with fungicidal effect might be a better candidate than pure antioxidant for the system of fungicide/antioxidant.     

Antifungal activities of essential oils and their constituents from indigenous cinnamon (Cinnamomum osmophloeum) leaves against wood decay fungi

Cinnamomum osmophloeum Kaneh is one of the hardwood species indigenous to Taiwan that possesses significant antifungal activity. To examine the antifungal activity of leaf essential oils and dominant constituents from C. osmophloeum, the essential oils of leaves from three clones (A, B, and C) collected from Haw-Lin experimental forest were extracted and their components analyzed by gas chromatography. Results from the antifungal tests demonstrated that the essential oils of both B and C leaves had strong inhibitory effects. The antifungal indices of these two leaf oils at 100 ppm against five strains of white rot fungi and four strains of brown rot fungi were all 100%. Cinnamaldehyde, the major compound in C. osmophloeum leaf essential oils, possessed the strongest antifungal activities compared with the other components. Its antifungal indices against both Coriolus versicolor and Laetiporus sulphureus were 100%. The MIC (minimum inhibitory concentration) of cinnamaldehyde against C. versicolor and L. sulphureus was 50 and 75 ppm, respectively. In addition, comparisons of the antifungal indices of cinnamaldehyde's congeners proved that cinnamaldehyde exhibited the strongest antifungal activities.     

Modification of wood with isopropyl glycidyl ether and its effects on decay resistance and light stability

China fir (Cunninghamia lanceolata var. lanceolata) and maple (Acer sp.) wood were etherified with isopropyl glycidyl ether and the decay resistance and light stability of the modified wood were assessed. CP/MAS (13)C NMR and FT-IR analyses indicated that new ether bonds containing isopropyl groups formed after reacting wood with isopropyl glycidyl ether. Modified wood samples were very resistant to decay when exposed to brown-rot fungus Laetiporus sulphureus or white-rot fungus Lenzites betulina for 60 days in the soil-block test. The isopropyl glycidyl ether treatment of wood was effective in decreasing formation of phenoxyl radicals upon UV irradiation and thus protecting wood from photodiscoloration.     

Evaluation of accelerated decay of wood plastic composites by Xylophagus fungi

The resistance to fungal attack of wood plastic composites (WPCs) containing 40% polypropylene and 60% either pine, maple or oak, wt%/wt%, was examined. WPCs specimens were made using the hot press system. Resistance to decay was evaluated using soil block and agar tests. Test specimens were exposed to either white-rot fungi, Trametes versicolor or Phanerochaete chrysosporium, or the brown-rot fungi Gloeophyllum trabeum or Postia placenta for six or 12 weeks. Moisture content and weight loss were used to assess the extent of decay of WPCs. Rates of decay in WPCs exposed in soil-block tests were greater than those exposed in the agar. WPCs containing either maple or oak were more susceptible to fungal attack then those containing pine.     

Effects of alkyl chain length of gallates on their antifungal property and potency as an environmentally benign preservative against wood-decay fungi

This study investigated effects of alkyl chain length of eight aliphatic gallates from C₁ to C₁₈ on their antifungal activity and free radical scavenging activity, which are two important indicators in developing wood preservatives. Results from the agar plate test showed that the antifungal activity against wood-rot fungi of gallates was related to alkyl chain length. It increased with increasing alkyl chain length, reaching a maximum at octyl gallate (C₈), and then decreased as chain length increased. Octyl gallate also exhibited potential antifungal activity against soft-rot Chaetomium globosum and copper-tolerant fungi Wolfiporia extensa and Poria placenta, which are difficult to combat with current copper-based wood preservatives. Octyl gallate is a potent antifungal agent with excellent antifungal activity over a broad antifungal spectrum. All of the gallates tested, regardless of their alkyl chain length, showed strong scavenging activity on the DPPH radical with EC₅₀ values around 1–5 μg ml^?1, indicating that the alkyl chain length was not directly related to this activity. Results from the soil block test showed that excellent antioxidants such as propyl gallate (C₃) and octyl gallate impart wood with good resistance against wood-decay fungi. This suggests that antioxidants have potential as environmentally benign wood preservatives.     

Evaluation of mold,decay and termite resistance of pine wood treated with zinc- and copper-based nanocompounds

In this work, the resistance of black pine wood (Pinus nigra L.) vacuum-treated with zinc oxide, zinc borate and copper oxide nanoparticles against mold and decay fungi and the subterranean termites was evaluated. Some of the nanocompounds tested were forced with acrylic emulsions to avoid leaching. Results showed that mold fungi were slightly inhibited by nanozinc borate, while the other nanometal preparations did not inhibit mold fungi. Mass loss from fungal attack by Trametes versicolor was significantly inhibited by the zinc-based preparations, while the brown-rot fungus, Tyromyces palustris was not inhibited by the nanometal treatments. Notably, nanozinc borate plus acrylic emulsion imparted very high resistance in pine wood to the white-rot fungus, T. versicolor with a mass loss of 1.8%. Following leaching, all pine specimens treated with nanozinc borate, with or without acrylic emulsion, strongly inhibited termite feeding, i.e. mass losses varying at 5.2–5.4%. In contrast, the copper-based treatments were much less effective against the subterranean termites, Coptotermes formosanus. In general, nanozinc borate possessed favorable properties, that is, inhibition of termite feeding and decay by T. versicolor.     

Comparison of phenanthrene and pyrene degradation by different wood-decaying fungi.

The degradation of phenanthrene and pyrene was investigated by using five different wood-decaying fungi. After 63 days of incubation in liquid culture, 13.8 and 4.3% of the [ring U-14C]phenantherene and 2.4 and 1.4% of the [4,5,9,10-14C]pyrene were mineralized by Trametes versicolor and Kuehneromyces mutabilis, respectively. No 14CO2 evolution was detected in either [14C]phenanthrene or [14C]pyrene liquid cultures of Flammulina velutipes, Laetiporus sulphureus, and Agrocybe aegerita. Cultivation in straw cultures demonstrated that, in addition to T. versicolor (15.5%) and K. mutabilis (5.0%), L. sulphureus (10.7%) and A. aegerita (3.7%) were also capable of mineralizing phenanthrene in a period of 63 days. Additionally, K. mutabilis (6.7%), L. sulphureus (4.3%), and A. aegerita (3.3%) mineralized [14C]pyrene in straw cultures. The highest mineralization of [14C] pyrene was detected in straw cultures of T. versicolor (34.1%), which suggested that mineralization of both compounds by fungi may be independent of the number of aromatic rings. Phenanthrene and pyrene metabolites were purified by high-performance liquid chromatography and identified by UV absorption, mass, and 1H nuclear magnetic resonance spectrometry. Fungi capable of mineralizing phenanthrene and pyrene in liquid culture produced enriched metabolites substituted in the K region (C-9,10 position of phenanthrene and C-4,5 position of pyrene), whereas all other fungi investigated produced metabolites substituted in the C-1,2, C-3,4, and C-9,10 positions of phenanthrene and the C-1 position of pyrene.     

Determination of fungal activity in modified wood by means of micro-calorimetry and determination of total esterase activity

Beech and pine wood blocks were treated with 1,3-dimethylol-4,5-dihydroxyethylen urea (DMDHEU) to increasing weight percent gains (WPG). The resistance of the treated specimens against Trametes versicolor and Coniophora puteana, determined as mass loss, increased with increasing WPG of DMDHEU. Metabolic activity of the fungi in the wood blocks was assessed as total esterase activity (TEA) based on the hydrolysis of fluorescein diacetate and as heat or energy production determined by isothermal micro-calorimetry. Both methods revealed that the fungal activity was related with the WPG and the mass loss caused by the fungi. Still, fungal activity was detected even in wood blocks of the highest WPG and showed that the treatment was not toxic to the fungi. Energy production showed a higher consistency with the mass loss after decay than TEA; higher mass loss was more stringently reflected by higher heat production rate. Heat production did not proceed linearly, possibly due to the inhibition of fungal activity by an excess of carbon dioxide.     

An NADH:quinone oxidoreductase active during biodegradation by the brown-rot basidiomycete Gloeophyllum trabeum

The brown-rot basidiomycete Gloeophyllum trabeum uses a quinone redox cycle to generate extracellular Fenton reagent, a key component of the biodegradative system expressed by this highly destructive wood decay fungus. The hitherto uncharacterized quinone reductase that drives this cycle is a potential target for inhibitors of wood decay. We have identified the major quinone reductase expressed by G. trabeum under conditions that elicit high levels of quinone redox cycling. The enzyme comprises two identical 22-kDa subunits, each with one molecule of flavin mononucleotide. It is specific for NADH as the reductant and uses the quinones produced by G. trabeum (2,5-dimethoxy-1,4-benzoquinone and 4,5-dimethoxy-1,2-benzoquinone) as electron acceptors. The affinity of the reductase for these quinones is so high that precise kinetic parameters were not obtainable, but it is clear that k(cat)/K(m) for the quinones is greater than 10(8) M(-1) s(-1). The reductase is encoded by a gene with substantial similarity to NAD(P)H:quinone reductase genes from other fungi. The G. trabeum quinone reductase may function in quinone detoxification, a role often proposed for these enzymes, but we hypothesize that the fungus has recruited it to drive extracellular oxyradical production.     

Fungal hydroquinones contribute to brown rot of wood

The fungi that cause brown rot of wood initiate lignocellulose breakdown with an extracellular Fenton system in which Fe(2+) and H(2)O(2) react to produce hydroxyl radicals (.OH), which then oxidize and cleave the wood holocellulose. One such fungus, Gloeophyllum trabeum, drives Fenton chemistry on defined media by reducing Fe(3+) and O(2) with two extracellular hydroquinones, 2,5-dimethoxyhydroquinone (2,5-DMHQ) and 4,5-dimethoxycatechol (4,5-DMC). However, it has never been shown that the hydroquinones contribute to brown rot of wood. We grew G. trabeum on spruce blocks and found that 2,5-DMHQ and 4,5-DMC were each present in the aqueous phase at concentrations near 20 microM after 1 week. We determined rate constants for the reactions of 2,5-DMHQ and 4,5-DMC with the Fe(3+)-oxalate complexes that predominate in wood undergoing brown rot, finding them to be 43 l mol(-1) s(-1) and 65 l mol(-1) s(-1) respectively. Using these values, we estimated that the average amount of hydroquinone-driven .OH production during the first week of decay was 11.5 micromol g(-1) dry weight of wood. Viscometry of the degraded wood holocellulose coupled with computer modelling showed that a number of the same general magnitude, 41.2 micromol oxidations per gram, was required to account for the depolymerization that occurred in the first week. Moreover, the decrease in holocellulose viscosity was correlated with the measured concentrations of hydroquinones. Therefore, hydroquinone-driven Fenton chemistry is one component of the biodegradative arsenal that G. trabeum expresses on wood.     

Isolation of laccase gene-specific sequences from white rot and brown rot fungi by PCR.

Degenerate primers corresponding to the consensus sequences of the copper-binding regions in the N-terminal domains of known basidiomycete laccases were used to isolate laccase gene-specific sequences from strains representing nine genera of wood rot fungi. All except three gave the expected PCR product of about 200 bp. Computer searches of the databases identified the sequence of each of the PCR products analyzed as a laccase gene sequence, suggesting the specificity of the primers. PCR products of the white rot fungi Ganoderma lucidum, Phlebia brevispora, and Trametes versicolor showed 65 to 74% nucleotide sequence similarity to each other; the similarity in deduced amino acid sequences was 83 to 91%. The PCR products of Lentinula edodes and Lentinus tigrinus, on the other hand, showed relatively low nucleotide and amino acid similarities (58 to 64 and 62 to 81%, respectively); however, these similarities were still much higher than when compared with the corresponding regions in the laccases of the ascomycete fungi Aspergillus nidulans and Neurospora crassa. A few of the white rot fungi, as well as Gloeophyllum trabeum, a brown rot fungus, gave a 144-bp PCR fragment which had a nucleotide sequence similarity of 60 to 71%. Demonstration of laccase activity in G. trabeum and several other brown rot fungi was of particular interest because these organisms were not previously shown to produce laccases.     

Effect of aromatic monomers on production of carbohydrate-degrading enzymes by white-rot and brown-rot fungi

Abstract The effects were studied of 12 monomeric aromatic compounds on the production of six carbohydrate-degrading enzymes of two brown-rot fungi, Postia placenta and Gloeophyllum trabeum , and one white-rot fungus, Coriolus versicolor . Most compounds were inhibitory to growth of the decay fungi at concentrations of 0.05%. At lower concentrations, the phenolics often stimulated growth. Relatively high concentrations (> 0.1%) of aromatic monomers were required to inhibit xylanase of P. placenta in situ. The effects of the monomers incorporated in liquid media on enzyme production varied depending on compound and fungal species. Some compounds were quite inhibitory to production of enzyme activities at very low concentrations. For example, catechol and vanillin (50 ppm) caused 100% inhibition of xylanase and β-1,4-endoglucanase production by P. placenta . However, no aromatic monomer was strongly inhibitory to production of all enzyme activities of all fungi.     

Decay resistance of ash,beech and maple wood modified with N-methylol melamine and a metal complex dye

This study evaluated the decay resistance of ash (Fraxinus excelsior L.), beech (Fagus sylvatica L.), and maple (Acer platanoides L.) wood impregnated by a full cell process with N-methylol melamine (NMM) and combined NMM-metal complex dye (NMM-BS) in aqueous solutions. Basidiomycete decay testing involved incubation with Coniophora puteana (brown rot) and Trametes versicolor (white rot) according to a modified EN 113 (1996) standard, while for the soft rot fungal resistance was evaluated following the standard ENv 807 (2001). NMM and NMM-BS modifications at a WPG range of 7–11% provided decay protection against brown rot resulting in a mass loss less than the required limit (3%). The NMM and NMM-BS modified wood showed increased resistance to white rot decay; however, a higher WPG is needed to prohibit attack from this hardwood specific fungus. The metal-complex dye alone revealed biocidal effects against basidiomycetes. An increased WPG in NMM or NMM-BS had a positive impact against soft rot decay and the lowest mass losses after 32 weeks of exposure were obtained with NMM modification at about 18–21% WPG. NMM modification at this WPG range, however, was not sufficient to protect the wood from soft rot decay. The wood of beech and maple showed slightly higher resistance to all decay types than ash, probably due to the poorer degree of modification of the latter.     

Localisation and characterisation of incipient brown-rot decay within spruce wood cell walls using FT-IR imaging microscopy

Spruce wood that had been degraded by brown-rot fungi (Gloeophyllum trabeum or Poria placenta) exhibiting mass losses up to 16% was investigated by transmission Fourier transform infrared (FT-IR) imaging microscopy. Here the first work on the application of FT-IR imaging microscopy and multivariate image analysis of fungal degraded wood is presented and the first report on the spatial distribution of polysaccharide degradation during incipient brown-rot of wood. Brown-rot starts to become significant in the outer cell wall regions (middle lamellae, primary cell walls, and the outer layer of the secondary cell wall S1). This pattern was detected even in a sample with non-detectable mass loss. Most significant during incipient decay was the cleavage of glycosidic bonds, i.e. depolymerisation of wood polysaccharides and the degradation of pectic substances. Accordingly, intramolecular hydrogen bonding within cellulose was reduced, while the presence of phenolic groups increased.     

丰林国家级自然保护区木腐真菌多样性与寄主倒木的关系

木腐真菌是一类以木材为生长基质的大型真菌, 通过分泌各种水解酶全部或部分降解木材中的木质素、纤维素和半纤维素, 促进森林生态系统的物质循环, 具有重要的生态功能。本研究调查了丰林国家级自然保护区固定样地中木腐真菌的多样性和倒木特征, 并进行了木腐真菌的物种多样性和数量与倒木的种类、数量、腐朽程度、直径大小等的相关性分析。结果显示: 在样地内共采集木腐真菌标本295份, 经鉴定为93种, Shannon多样性指数为3.86, Simpson指数为0.96。相关性分析发现木腐真菌的数量和种类与直径为2-5 cm和5-10 cm的倒木、2级腐烂的倒木和红松倒木均显著相关。样地中优势倒木寄主分别为槭属(Acer)、榛属(Corylus)、云杉属(Picea)和松属(Pinus), 这4类倒木上生长的木腐真菌种类组成具有明显的差异, 槭属和榛属倒木上的共有优势种主要是三色拟迷孔菌(Daedaleopsis tricolor)、云芝(Trametes versicolor)和桦附毛孔菌(Trichaptum pargamenum), 而松属和云杉属的共有优势种主要有白囊耙齿菌(Irpex lacteus)、云芝、冷杉附毛孔菌(Trichaptum abietinum)和褐紫附毛孔菌(T. fuscoviolaceum)。倒木产生真菌子实体的概率研究表明, 同一类寄主倒木上发生木腐真菌子实体的概率在调查面积增加到0.36 ha后趋于一个定值, 松属倒木中仅有10.2%产生真菌子实体, 槭属和云杉属分别是12.9%和13.4%, 榛属最高, 达到53.7%。本研究结果对于预测森林生态系统中木腐真菌的发生具有重要理论意义。     

Competition between two wood-degrading fungi with distinct influences on residues

Many wood-degrading fungi colonize specific types of forest trees, but often lack wood specificity in pure culture. This suggests that wood type affects competition among fungi and indirectly influences the soil residues generated. While assessing wood residues is an established science, linking this information to dominant fungal colonizers has proven to be difficult. In the studies presented here, we used isolate-specific quantitative PCR to quantify competitive success between two distinct fungi, Gloeophyllum trabeum and Irpex lacteus, brown and white rot fungi, respectively, colonizing three wood types (birch, pine, oak). Ergosterol (fungal biomass), fungal species-specific DNA copy numbers, mass loss, pH, carbon fractions, and alkali solubility were determined 3 and 8 weeks postinoculation from replicate wood sections. Quantitative PCR analyses indicated that I. lacteus consistently outcompeted G. trabeum, by several orders of magnitude, on all wood types. Consequently, wood residues exhibited distinct characteristics of white rot. Our results show that competitive interactions between fungal species can influence colonization success, and that this can have significant consequences on the outcomes of wood decomposition.     

Pyranose Oxidase, a Major Source of H(2)O(2) during Wood Degradation by Phanerochaete chrysosporium, Trametes versicolor, and Oudemansiella mucida

The production of the H(2)O(2)-generating enzyme pyranose oxidase (POD) (EC 1.1.3.10) (synonym, glucose 2-oxidase), two ligninolytic peroxidases, and laccase in wood decayed by three white rot fungi was investigated by correlated biochemical, immunological, and transmission electron microscopic techniques. Enzyme activities were assayed in extracts from decayed birch wood blocks obtained by a novel extraction procedure. With the coupled peroxidase-chromogen (3-dimethylaminobenzoic acid plus 3-methyl-2-benzothiazolinone hydrazone hydrochloride) spectrophotometric assay, the highest POD activities were detected in wood blocks degraded for 4 months and were for Phanerochaete chrysosporium (149 mU g [dry weight] of decayed wood), Trametes versicolor (45 mU g), and Oudemansiella mucida (1.2 mU g), corresponding to wood dry weight losses of 74, 58, and 13%, respectively. Mn-dependent peroxidase activities in the same extracts were comparable to those of POD, while lignin peroxidase activity was below the detection limit for all fungi with the veratryl alcohol assay. Laccase activity was high with T. versicolor (422 mU g after 4 months), in trace levels with O. mucida, and undetectable in P. chrysosporium extracts. Evidence for C-2 specificity of POD was shown by thin-layer chromatography detection of 2-keto-d-glucose as the reaction product. By transmission electron microscopy-immunocytochemistry, POD was found to be preferentially localized in the hyphal periplasmic space of P. chrysosporium and O. mucida and associated with membranous materials in hyphae growing within the cell lumina or cell walls of partially and highly degraded birch fibers. An extracellular distribution of POD associated with slime coating wood cell walls was also noted. The periplasmic distribution in hyphae and extracellular location of POD are consistent with the reported ultrastructural distribution of H(2)O(2)-dependent Mn-dependent peroxidases. This fact and the dominant presence of POD and Mn-dependent peroxidase in extracts from degraded wood suggest a cooperative role of the two enzymes during white rot decay by the test fungi.     

Degradation of Wood Preservatives by Fungi

Wood-inhabiting fungi, not necessarily responsible for major decay, are shown to be capable of degrading a toxic compound into a less potent form, thus rendering it less effective in protecting wood from decay by less-tolerant basidiomycetous wood-destroyers. Sweetgum or pine sapwood blocks treated with preservatives (ammoniacal copper arsenate, fluor-chrome-arsenate-dinitrophenol, a creosote or pentachlorophenol) were exposed progressively to two different wood-inhabiting fungi with sterilization between the first and second exposure. The fungus in the first exposure was usually an Ascomycete or a Fungi Imperfecti-Chaetomium globosum, Phoma, Orbicula, Graphium, Pestalozzia, or Trichoderma species, isolated from wood below the ground. In one experiment, the fungus in the first exposure was a basidiomycete, Lenzites trabea or Polyporus versicolor. The second fungus, a prominent Basidiomycete-Coniophora puteana, Lentinus lepideus, or Lenzites trabea-was the bioassay fungus, since its purpose was to show whether the first fungus had degraded the preservative. Generally, the treated block, except where exposed to another fungus, remained virtually untouched by the bioassay fungus. Clearly, therefore, the first fungus had rendered the preservative ineffective but without appreciably decaying the wood itself Chemical analyses of treated blocks indicated that in the first exposure the fungi had substantially depleted sodium arsenate and pentachlorophenol.