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Using DNA probes to characterize the metabolic pathway of pigment production in several wood-staining fungi
1996 - IRG/WP 96-10146
During shipment and storage, lumber is susceptible to sapstain, a wood discoloration caused by fungi. Currently kiln drying and chemical applications are used to control sapstain. However, the chemicals used to protect wood have a broad range of action, and so can affect other organisms. In addition, in Canada most of these chemicals are under temporary registration. Thus there is a need to develop alternative strategies for wood protection. Instead of inhibiting fungal growth one approach would be to block the production of the fungal pigment responsible for discoloration. Very little is known about pigmentation in sapstaining fungi. However, in Ophiostoma piliferum, Ophiostoma piceae and Alternaria alternata, the discoloration is due to melanin production. While fungal melanin can be synthesized by several different metabolic pathways, Alternaria alternata produces melanin via the dihydroxynapthalene (DHN) pathway. To determine whether several common sapstaining fungi also utilize this pathway, a gene from Alternaria alternata's DHN pathway was radiolabeled and used as heterologous probe to screen Southern blots from six species of staining fungi. The results suggest that most of these fungi have homologous (similar) genes for the enzymes of the DHN pathway. The genes from Ophiostoma piceae will be further characterized, to facilitate more directed development of anti stain strategies.
R Eagen, S Riecken, J Kronstad, C Breuil


Integrated protection of freshly sawn lumber using Bacillus subtilis and selected fungicide
1997 - IRG/WP 97-10235
Bioprotection against stain fungi has tremendous potential for reducing discoloration of freshly sawn wood while decreasing chemical consumption. Unfortunately, most bioprotectants appear to be unable to consistently perform under the array of conditions to which freshly sawn wood is exposed. While research is underway to understand the nature of the inconsistent performance, a more pragmatic approach to solving this problem is to alter the environment to more consistently favor the bioprotectant. One method for accomplishing this task is to apply low levels of biocides at the same time as the bioprotectant is applied. The biocide, although used below the threshold tor preventing fungal growth, should render the stain fungi less fit and, therefore, more susceptible to control. In this report, we evaluated the effect of 3 commonly used fungicide mixtures on the ability of B. subtilis to inhibit discoloration by a mixture of Ophiostoma perfectum, Phialphora spp., and Alternaria alternata on Pinus ponderosa sapwood under laboratory conditions. Bacillus subtilis provided poor control of discoloration. The addition of fungicide produced no enhancement of bioprotection. Evaluation of bacterial cultures containing this fungicide indicated that the chemicals had a profound effect on bacterial filters.
M E Mankowski, M Anderson, J J Morrell


Utilisation of carbohydrates by stain fungi in agar culture
1998 - IRG/WP 98-10248
Stain fungi are often defined by their ability to utilise the starch and free sugars found in ray parenchyma cells, and their inability to utilise other wood constituents. However, several species of stain fungi produce bore holes in wood cell walls. This suggests that enzymatic activity capable of degrading structural polysaccharides and/or lignin is associated with the growth of the appressorium and transpressorium structures developed by these stain fungi. This pilot study examined possible base media for growth of three common blue-stain fungi isolated from hardwood sawmills in Victoria, Australia. Alternaria alternata (Fr.) Keissler, Graphium/Ophiostoma sp., and Aureobasidium pullulans (de Bary) Arnaud were grown on agar supplemented with a variety of carbon sources, and mycelial growth rates were measured to determine which carbohydrates can be used by these fungi.
J Snow, P Vinden, S M Read


Wood decay of Pinus sylvestris L. by marine fungi
1990 - IRG/WP 1463
Waterlogged wood decay by marine microorganisms represents a major problem for the conservation of wood structures of historic value. It is important to know which kind of decay affects the wood from a conservation point of view. Enzyme activities of 14 marine fungi belonging to several localities were studied. Also, the weight loss and the rot type suffered by the wood at a microscopic level were studied, in comparison with 3 standard rot-producing fungi (white rot, brown rot and soft rot).
M C Escorial, M T De Troya, J E Garcia de los Rios