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Biological control with Trichoderma harzianum in relation to the formation for spores the production of soluble metabolites
1994 - IRG/WP 94-10073
The amount of spores produced by three strains of Trichoderma harzianum on the aerial mycelium of agar cultures and in shake cultures, respectively, correlated with the inhibition zones exerted against Phanerochaete chrysosporium in an agar diffusion test. The amount of soluble antifungal metabolites as well as the protein content also correlated with the inhibition zones and the amount of spores produced. The antifungal metabolites were identified to be trichorzianines. They were the only compounds with antifungal activity. It is concluded that the trichorzianines are responsible for the biocontrol effect by soluble metabolites and that they are produced during conidiogenesis.
J Bürgel, E Horvath, J Haschka, K Messner
Antifungal properties of metabolites produced by Trichoderma isolates from sawdust media of edible fungi against wood decay fungi
1994 - IRG/WP 94-10051
Trichoderma isolated from a sawdust medium of Pholiota nameko produced filtrates which had antifungal activities to four wood decay fungi tested on the agar plates. Filtrates produced from another isolate, from a sawdust medium of Lentinus edodes, had antifungal activities only to the white rot fungi, Coriolus versicolor and Pycnoporus coccineus. These results did not agree with those from earlier decay tests using wood blocks pretreated with the isolates. The difference of antagonistic potential was possibly due to the different condition of incubation procedure.
S Doi, M Mori
Antifungal activity in metabolites from Streptomyces rimosus
1991 - IRG/WP 1495
The objective of this study was to evaluate the efficacy of antifungal metabolites from Streptomyces rimosus for controlling the growth of sapwood-inhabiting fungi: sapstain fungi - Ceratocystis coerulescens, Ceratocystis minor, Ceratocystis pilifera, and Aureobasidum pullulans; mold fungi - Aspergillus niger, Penicillium spp, and Trichoderma spp. Production of antifungal metabolites by Streptomyces rimosus was studied using petri plate assay, plate bio-assay, wood-block tests, and green pine log sections. The metabolites inhibited mycelial growth at a distance in petri plate assay; clear zones were exhibited around the wells in plate bio-assay. Treatment of Southern Pine and sweetgum blocks and green pine log sections with concentrated metabolites inhibited conidial germination and prevented discoloration.
S C Croan, T L Highley
Antifungal Essential Oil Metabolites
2010 - IRG/WP 10-30531
New environmentally-friendly wood protection systems based on “green” technologies are needed to inhibit wood-inhabiting mold and decay fungi. Utilizing bioactive essential oils from select herbaceous plants is one promising approach, but the concentrations of bioactive compounds are somewhat variable even in the highest (therapeutic) grade essential oils. Purified primary metabolites from four bioactive plant essential oils were evaluated for antifungal activity in southern pine treated with those compounds. Purified carvone, citronellol, geraniol, thymol and borneol inhibited growth of Aspergillus niger, Penicillium chrysogenum and Trichoderma viride for 12 weeks at concentrations equal to or less than those present in therapeutic grade essential oils. Thymol and borneol effectively inhibited two brown-rot fungi, Postia placenta and Gloeophyllum trabeum and one white-rot fungus, Trametes versicolor, but other metabolites tested were ineffective against the decay fungi. Select purified bioactive metabolites of essential oils effectively inhibit fungi that inhabit wood and wood products.
C A Clausen, B M Woodward, V W Yang
Synergistic effect of boron on Streptomyces rimosus metabolites in preventing conidial germination of sapstain and mold fungi
1992 - IRG/WP 92-1565
We evaluated the synergistic effect of boron (4% BAE solution of Tim-Bor or 4% boric acid) on Streptomyces rimosus metabolites in preventing spore germination of sapstain and mold fungi using plate bioassay, Southern yellow pine and sweetgum block tests, and green pine log sections: sapstain -- Ceratocystis coerulescens, Ceratocystis minor, and Aureobasidum pullulans; mold fungi -- Aspergillus niger, Penicillium spp, and Trichoderma spp. Inhibition of spore germination in plate bioassay by metabolites with boron was more effective than without added boron. Treatment of wood samples with the mixture of boron and unconcentrated metabolites also resulted in the synergistic effect and completely inhibited spore germination of sapstain and mold fungi.
S C Croan, T L Highley
Antifungal mechanism of dichloro-N-octylisothiazolone
1998 - IRG/WP 98-30183
4,5-dichloro-N-octylisothiazolin-3-one (DCOI) is a member of the isothiazolone class of preservatives, whose antimicrobial mechanism of action has been intensively studied over the last decade. DCOI has also been intensively studied for use in wood preservation. The isothiazolones are electrophilic molecules that rapidly react with thiol groups to form covalently bonded isothiazolone-thiol adducts. This ability to bond with thiol groups is crucial to their ability to act as preservatives. Thiol groups are present in proteins as part of the amino acid cysteine, where they play an important role in maintaining protein structure and function. A number of enzymes have thiol groups at the site where the enzyme function is performed, and these thiol groups may participate in the enzyme reaction. If the isothiazolone reacts with this thiol group, the activity of the enzyme is inhibited. Our studies have shown that there are several enzymes in the Krebs cycle that are inhibited by isothiazolones and these enzymes are required to generate energy and perform many biosynthetic functions. Reflective of this, DCOI has been shown to be a rapid inhibitor of cellular respiration, causing the cell to cease consuming oxygen almost immediately upon contact with DCOI. The multiplicity of targets and their central importance to the metabolism of the cell, as well as the fact that all microbes use at least parts of the Krebs cycle, can be related to the low use levels and broad spectrum of activity of DCOI. The antimicrobial mechanism of DCOI results in a potent rapid-acting preservative with a broad spectrum of antifungal and antibacterial activity that is effective at low levels.
J S Chapman, M A Diehl, K B Fearnside, L E Leightley
Antifungal activity of a stilbene glucoside from the bark of Picea glehnii
2001 - IRG/WP 01-10402
Stilbene glucosides are widely distributed as phenolic extractives in the bark of Picea glehnii, a commercially species planted in the northern area of Japan, and its content reaches to more than 10% by the dried weight of the bark. Although antifungal activities of these compounds have been reported, the mechanism of growth inhibition is still unclear. Isorhapontin (5,4'-dihydroxy-3'-methoxystilbene-3-ß-D-glucoside) is the major constituent of the stilbene glucosides in the bark of P. glehnii. In the present work, the relation between metabolism and antifungal activities of isorhapontin for the white-rot fungus Phanerochaete chrysosporium and the wood staining fungus Trichoderma viride was investigated. Inhibition of fungal growth was obviously depending on the conversion of isorhapontin to the aglycone isorhapontigenin (3'-methoxy-3,5,4'-trihydroxystilbene) by ß-glucosidic activities in the cultures. Exogenous addition of ß-glucosidase also enhances the antifungal activity of isorhapontin. Moreover, less than 100 ppm addition of the stilbene aglycone isorhapontigenin is sufficient to inhibit the growth of both fungi. However, further metabolism of isorhapontigenin was observed after prolonged incubation of the fungi and resulted in detoxification.
S Shibutani, M Samejima
Antifungal properties of new quaternary ammonium and imidazolium salts against wood decay, staining and mould fungi
2004 - IRG/WP 04-30347
The biological activity of twenty-four potential wood preservatives – imidazolium and quaternary ammonium salts with a modified anion structure was determined employing screening agar-plate and agar-block methods. Experiments were carried out on Scots pine (Pinus sylvestris L.) wood. The aim of the performed studies was to investigate the effect of structure modification of IC and QAC with organic anions or copper (ll) and zinc complexes on their biological activity against wood decay, staining and mould fungi. The fungicidal value of new compounds for Coniophora puteana ranged from 0.64 kg/m3 to 2.2 kg/m3. Aspergillus niger turned out to be the most resistant fungus to the action of modified IC and QACs, whereas Sclerophoma pityophila was effectively inhibited by the examined salts. The performed soil-block tests showed that the IC and QAC were leached from the experimental wood in conditions of contact with moist soil and revealed their fungal detoxification by mould fungi, especially by Gliocladium roseum. Observations made using the scanning electron microscope of the colonization and decay of treated wood by mould fungi confirmed tolerance of mould fungi to QACs.
J Zabielska-Matejuk, W Wieczorek
Inhibition of termite feeding by fungal siderophores
1992 - IRG/WP 92-1558
Siderophores are iron-chelating extracellular fungal metabolites which may be involved in initiating wood decay. A purified siderophore extract isolated from the brown-rot decay fungus Gloeophyllum trabeum (Pers. ex Fr.) Murr. (Basidiomycetes: Polyporaceae) was found to deter feeding by Formosan subterranean termites, Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae). This fungus has previously been associated with preferential feeding on decayed wood by subterranean termites, and solvent extracts have been reported to induce termite trail-following, arrestment, and/or aggregation. This is the first report of Gloephyllum trabeum metabolites or fungal siderophores having a negative behavioral effect on subterranean termites.
J K Grace, B Goodell, W E Jones, V Chandhoke, J Jellison
Immunolocalization of extracellular metabolites from Tyromyces palustris
1991 - IRG/WP 1491
Polyclonal antisera produced to extracellular metabolites from the brown-rot fungus Tyromyces palustris was used in immunogold TEM studies. Gold labelling was detected in the fungal cell wall and extracellular slime layer but little or sporadic labelling was noted within the cytoplasm of the fungal hyphae. Gold particles were also found within the wood cell wall of Pinus densiflora decayed by Tyromyces palustris. Erosion of wood cell wall and penetration of hyphae in the wood cell wall were frequently observed. The degradation pattern of lignocellulose by brown-rot fungus was also discussed.
Yoon Soo Kim
Controlling the sapstain fungus Ceratocystis coerulescens by metabolites obtained from Bjerkandera adusta and Talaromyces flavus
1993 - IRG/WP 93-10024
Sapstain causes severe damage to wood and wood products, posing a major economic problem for the wood industry. The purpose of this study was to determine if metabolites from Bjerkandera adusta and Talaromyces flavus would (1) decolorize stain in wood caused by Ceratocystis coerulescens and (2) prevent sapstain by Ceratocystis coerulescens. We studied the interaction of the sapstain fungus Ceratocystis coerulescens against the test fungi Bjerkandera adusta and Talaromyces flavus in dual cultures on agar medium. The metabolites obtained from test fungi were examined on pine veener disks stained by Ceratocystis coerulescens. Our results indicate that the test fungi were antagonistic to the sapstain fungus Ceratocystis coerulescens. The combination of metabolites from the antagonists decolorize the sapstained pine veener disks and killed the existing growth of Ceratocystis coerulescens.
S C Croan, T L Highley
The antifungal efficacy of Guayule resin
1987 - IRG/WP 3429
The Naval Research Laboratory is evaluating the non-rubber-producing portion of guayule (Parthenium argentatum) resin as a protectant for wood in terrestrial and marine service. This study phase, in collaboration with the universities of Arizona and Mississippi State, evaluates the resin's fungicidal worth. Resin-impregnated pine sapwood was exposed to brown rot fungi (Gloeophyllum trabeum, Antrodia carbonica, Formitopsis cajanderi, Lentinus ponderosa), white rot fungi (Dichomitus squalens, Trametes versicolor, Ganoderma sp.), and a natural inoculum of soft rot fungi from unsterile soil. The exposures for the brown and white rot fungi lasted 20 weeks, using malt agar chambers inoculated 2 weeks prior to the introduction of the treated wood; the soft rot exposure lasted 12 weeks and included treated birch specimens. Weight loss data showed a definite inhibition of decay of the treated wood by the brown and white rot fungi, however there was some decay caused by Lentinus ponderosa (closely related to creosote-tolerant Lentinus lepideus) and by Antrodia carbonica, a common utility pole fungus. None of the resin-impregnated pine or birch specimens were attacked by the soft rot fungi, even those specimens containing the lowest of the three resin concentrations in the wood. In both sets of exposures all of the controls were decayed.
J D Bultman, R L Gilbertson, T L Amburgey, J E Adaskaveg, S V Parikh, C A Bailey
Control of sapwood-inhabiting fungi by fractionated extracellular metabolites from Coniophora puteana
1991 - IRG/WP 1494
The objective of this study was to test the fractionated metabolites released by Coniophora puteana for their antagonistic activity against the sapstain fungi Ceratocystis coerulescens and Aureobasidum pullulans, and the molds Asperigillus niger and Penicillium spp. The acetone-soluble fraction obtained from the culture filtrate prepared from Coniophora puteana grown on 6% malt extract agar inhibited mycelial growth in a plate bioassay. The <5k-Da fraction separated from the acetone-soluble fraction also inhibited mycelial growth in the plate bioassay and prevented attack by Ceratocystis coerulescens in wood.
S C Croan, T L Highley
Immuno-electron microscopic localization of extracellular metabolites in spruce wood decayed by brown-rot fungus Postia placenta
1990 - IRG/WP 1441
Degradation by Postia placenta in spruce and birch wood was shown to occur not only in the wood cell wall but also in the middle lamellae region. Middle lamellae was often found to be degraded along the centerline so that cells could separate along this line. Extracellular membrane structures were found surrounding the hyphae and this matrix labelled positively with antisera produced to Postia placenta extracellular metabolites. This matrix was also visible in the secondary wall of degraded birch wood. Antisera labelling was also noted in the secondary cell walls of the wood cells, but not in the middle lamellae region.
Y S Kim, B Goodell, J Jellison
Biological control of decay
1975 - IRG/WP 135
One approach to the biological control of decay in standing poles, live trees or seedlings is with microbial immunising commensals or IC.·These are microorganisms able to grow in the wood without damaging it and as a result of such growth to protect against certain types of decay. Scytalidium and Trichoderma spp have been tested in the field. The latter species have shown an establishment rate in excess of 80% in field tests made with standing creosote treated poles during the past 4 years. In live trees, higher rates can be expected. These IC are known for their antagonistic properties against various Basidiomycetes and their innocuity to man and environment.
Effect of Volatiles from Trichoderma species on the regulation of protein synthesis in Serpula lacrymans isolates
2002 - IRG/WP 02-10440
The growth of wood decay fungi has previously been shown to be inhibited by volatile organic compounds (VOCs) from selected Trichoderma isolates. No mechanism of action has however been established for such inhibition. This paper reports the effects of VOCs produced by Trichoderma pseudokoningii, T. viride and T. aureoviride on the growth of four dry rot isolates and corresponding protein synthesis in two of these Serpula lacrymans strains. Volatile inhibition of growth was measured using a simple plate bioassay with S.lacrymans mycelium subsequently extracted and protein profiles analysed by SDS-PAGE. Two S.lacrymans strains isolated from building timbers were generally more sensitive to the Trichoderma VOCs compared with a strain isolated from the Himilayas or a standard lab culture strain. VOCs from T. aureoviride and T. viride affected protein synthesis in both target S. lacrymans strains, but those from T. pseudokoningii.had no effect. These results mirrored the patterns of growth inhibition in the target fungi with VOCs from T.pseudokoningii having little effect on growth of the dry rot fungi. Interestingly, when the antagonists were removed growth of the S. lacrymans isolates resumed and the original protein patterns were restored. This suggests that the VOCs act on the basic expression of proteins by the S. lacrymans rather than interfering with protein function after synthesis.
S Humphris, R Wheatley, E Buultjens, A Bruce
Antagonistic effect of Trichoderma spp. against basidiospores
1993 - IRG/WP 93-10027
All screening of potential biocontrol agents of wood decay fungi have previously been used against basidiomycete mycelium. Similarly, experiments designed to evaluate the mechanisms involved in antagonism (soluble metabolites and volatile antibiotics) between biological control agents and target fungi have always been carried out on mycelial inoculum. Basidiospores are a primary source of infection leading to decay of wood exposed above ground and are the pathogenic form of the target fungus contact with a biocontrol antagonist. This paper examines the antagonistic responses of Trichoderma spp. against wood decay basidiospores. The paper also examines the influence of nutrient composition of growth media on the antagonistic responses by Trichoderma isolates. Assessment of individual modes of antagonism were carried out on two media types, a 3% malt extract agar and a nutritionally poorer minimal medium. The outcome of antagonism between Trichoderma isolates and wood decay basidiospores was often found to be dependent on the media type. Further studies were also carried out to evaluate the extent of inhibition of the basidiospores by concentrated soluble metabolites of Trichoderma isolates in vitro and in vivo i.e., in wood. The significance of using mycelial or spore inoculum with respect to antagonism for screening of biological control agents for wood protection is discussed.
U Srinivasan, T L Highley, S C Croan, A Bruce
Detection of dry rot by air analysis
1992 - IRG/WP 92-2399
Detection of dry rot (Serpula lacrymans) at an early stage appears to be very difficult in practice. Also control inspections in buildings, after remedial treatment of dry rot, have a limited accuracy. The use of trained dogs in Denmark initiated the idea for this research on the possible use of air analysis as a detection method. The Centre for Timber Research-TNO (TNO-CHT) and the Institute for Biotechnology and Chemistry therefore started a research programme sponsored by the Ministry of Housing, Physical Planning and Environmental Management in the Netherlands. The Centre for Timber Research has cultured under controlled laboratory conditions Serpula lacrymans and seven other fungi, which frequently occur in building structures. From these cultures air samples were taken and analysed by IBC-TNO, using GC-MS. Results indicate, that each fungus has it's own specific "blueprint" of volatile metabolic compounds. Though this is a promising start, further research is necessary to see, how growth conditions and environment may influence the consistency of the air analysis. This air analysis, could have application as another non-destructive detection method for decay caused by fungi. Other potential applications also need exploring.
P Esser, A C Tas
Immunolocalization of extracellular metabolites from Poria placenta
1988 - IRG/WP 1361
Polyclonal antisera produced to Poria placenta extracellular metabolites was used in immuno-fluoresence microscopy and immuno-gold TEM studies. In the fluorescence work, labelling of Poria placenta hyphae in wet fixed wood material was observed but not in infected wood which was oven dried prior to sectioning and immunolabelling. TEM studies provided better resolution, with gold labelling detected in the extracellular slime layer surrounding hyphae. Labelling occurred within the wood cell wall, but little non-specific labelling was noted within the cytoplasm of the fungal hyphae. A vesicle-like body within the hyphae did exhibit specific labelling.
B Goodell, G F Daniel, J Jellison, T Nilsson
Control of wood biodeterioration by fungal metabolites
1992 - IRG/WP 92-1527
Treating wood with different conventional preservative chemicals for protection and economic utilisation is well known. Tough some of these chemicals are toxic to skin, their use as wood preservative is unavoidable as they should be toxic to biodeteriorating organisms also. Recent advances in chemistry of natural products enabled the use of wood extractives as biocidal compounds against biodeteriorating organisms. Similary metabolites of marine organisms such as sponge, moluscus, horse shoe crabs, have been suggested as useful wood preservative substances. Many fungi colonise wood, interact each other during their succession, and produce toxic metabolites for their survival and dominance. Prelimirlary studies on these metabolites, when tested, showed inhibitory effect on some of the known wood rotting fungi, which has prompted, to make an attempt to use the fungal culture filtrate as possible wood preservatives. Keeping this in view, fungal culture filtrates of Trichoderma viridae; Sporotrichum Pulverulentum; Chaetomium globulosum and Penicillium spinolosum were extracted with kerosine for use as possible preservatives. Rubber and Mango wood were treated with these Fungal Culture Filtrate (FCF) and then were exposed to Brown an white rots to find out the induced resistance. Treated wood were also exposed to field conditions to find out preservative action under natural conditions.
H S Ananthapadmanabha, H C Nagaveni, V V Srinivasan
Free radical process controlled by manganese peroxidase and lipid-related metabolites produced by Ceriporiopsis subvermispora
2001 - IRG/WP 01-10412
Ceriporiopsis subvermispora, a specific lignin-degrading fungus produced free unsaturated fatty acids (USFAs) including 9,12-octadecaienoic asid, together with saturated fatty acids (SFAs) at an incipient stage of cultivation on wood meal cultures. In prolonged cultivation period after two weeks, the amount of intact fatty acids decreased with increasing in organic hydroperoxide and TBARS production. To analyze the free radical reactions of linoleic acid with MnP, the fungal metabolite was reacted with MnP from C. subvermispora and the radicals produced were analyzes by ESR. The in vitro spectroscopic analysis demonstrated that MnP-dependent lipid peroxidation is not initiated by direct ion of hydrogen from bis-allylic position during turnover but proceeds by a Mn(III)-dependent hydrogen ion from enols and subsequent propagation reactions involving the formation of acyl radical from lipid hydroperoxid. This finding expands the role of chelated Mn(III) from a phenol oxidant to a strong generator of free radicals from lipids and lipid hydroperoxides in lignin biodegradation. Possible roles of the free radical reactions in selective lignolysis is discussed.
T Watanabe, M Enoki, S Sato, Y Honda, M Kuwahara, N Shirai, K Messner
Production of monoclonal antibodies to fungal metabolites
1986 - IRG/WP 1306
The role of fungal extracellular enzymes in wood biodegradation is incompletely understood. Our lab is beginning a project utilizing monoclonal antibodies to characterize extracellular metabolites of the brown rot fungus Poria placenta Fr. (Cooke). Monoclonal antibody technology takes advantage of the ability of antibody secreting spleen cells from immunized mice to fuse in the presence of polyethylene glycol (PEG) with myeloma cells, which do not produce antibodies but do have the ability to grow in culture. The resultant hybrid cell or hybridoma has the capacity to produce antibodies of predetermined specificity and to grow "immortally" in culture. These hybridomas can be grown on a selective media, cloned, and the highly specific antibodies they produce purified. Monoclonals can be produced to fungal enzymes or other metabolites of interest. Monoclonal antibodies are capable of being more specific for a particular antigen than polyclonal antibodies because each B-lymphocyte (removed from the spleen) produces only one specific antibody to an antigen fraction. In our research, injection of extracellular fungal filtrates into an animal presents the immune system with a variety of antigen sites to produce antibodies to not only the target antigen (a glucosidase, for example) but also to extraneous materials injected with the extracellular filtrate. Two approaches exist to implement production of antisera to the desired antigen. One is to purify the antigen prior to injection. This solution has obvious advantages but it also has disadvantages.
J Jellison, B Goodell
In vitro antifungal activity of chilli against wood degrading fungi
2006 - IRG/WP 06-10572
The efficacy of chilli juice and/or chilli extract oleoresin as antisapstain agents was evaluated against two common sapstain fungi, Sphaeropsis sapinea and Leptographium procerum. Possible synergy between chilli juice and Lactobacillus casei as antisapstain agents was also assessed. Both the chilli juice and the oleoresin showed moderate antifungal activity. No growth of the test fungi was observed on plates amended with 50% chilli juice after 3 weeks of incubation. In the presence of 0.1% oleoresins, fungal biomass was reduced by more than half when compared with unamended controls. The synergy between chilli and Lactobacillus casei was apparent; the combination of chilli/L. casei treatment system afforded much better inhibition than chilli or L. casei alone. In the presence of 25% chilli juice with L. casei the growth of test fungi was stopped.
T Singh, C Chittenden, D Vesentini
Antifungal activity of plant derived extracts against G. trabeum
2007 - IRG/WP 07-30433
While synthetic chemicals have provided excellent protection to woods used in adverse environments, the general public remains interested in naturally derived wood protectants. There are diverse arrays of possible candidates, but many of these compounds are not readily water soluble and efforts to render them soluble often reduce biological activity. In this report, we describe efforts to enhance water solubility of various plant extracts, while retaining activity against Gloeophyllum trabeum, a common wood decay fungus. The results suggest that polyvinylpyrrolidones have potential as co-solvents for many plant extracts.
M Maoz, I Weitz, M Blumenfeld, C Freitag, J J Morrell
Detection of Anti-Fungal Sapwood Extractives in Non-Durable Scots Pine (Pinus sylvestris), Rubberwood (Hevea brasiliensis) and Jelutong (Dyera costulata)
2007 - IRG/WP 07-10634
A general laboratory bioassay method of Woodward and Pearce (1985) was adopted to detect anti-fungal activity of sapwood or heartwood extractives of 5 Malaysian hardwoods [dark red meranti heartwood (Shorea spp.), red balau heartwood (Shorea spp.), kulim heartwood (Scorodocarpus borneensis), jelutong sapwood (Dyera costulata) and rubberwood sapwood (Hevea brasiliensis), including the temperate Pinus sylvestris (Scots pine sapwood). The heartwoods of these species and Scots pine sapwood are known to be highly resistant to decay by soft-rotting Ascomycetes and anamorphic fungi (about 1-7% wood mass loss), while the sapwoods of rubberwood and jelutong had much reduced soft rot resistance (respectively 35, 32% wood mass loss) but obviously prone to sapstain and mold attack, including that of Scots pine. Crude methanol extracts of woodmeal samples of each wood species were loaded on to thin-layer chromatography plates at between 0.003 and 0.1 g fresh mass equivalent of woodmeal per spot so as to optimize resolution of separated compounds, and developed with chloroform:methanol solvent (ratio 19:1). The dried plates were sprayed with fresh fungal spores of Cladosporium cucumerinum and incubated at >90% RH for 5 days in the dark. Presence of anti-fungal compounds was revealed by white regions along the solvent transect for each extract of each species where inhibited spore germination and mycelial growth of C. cucumerinum occurred. Comparisons of anti-fungal activity of extracts between species and between sapwood and heartwood were made. Results revealed that several zones of inhibitory activity, indicated by their Rf-values, were clearly visible on chromatographic separations of methanol extracts of these 5 wood species. The inhibitory zones for 2 heartwood extracts (except kulim) did not move from the origin which was also resistant to infection. However inhibition zones were also detected for the sapwoods of rubberwood, jelutong and Scots pine against C. cucumerinum despite the known sapstain and decay susceptibility of these wood substrates. The presence of hitherto unidentified anti-fungal compounds in the sapwoods of these species may elicit limited potency or narrow spectrum protection from fungal infection and onset of stain or decay.
A H H Wong, R B Pearce