In this study a quantitative analysis of the low molecular carbohydrates (predominantly sucrose, fructose and glucose) in a series of lumber samples of Pinus sylvestris and Picea abies taken at various distances from the surface has been made. The increase of nitrogenous compounds towards the surface had been shown in a previous study. Several of the lumber samples showed a marked sugar accumulation at the surface, which correlated quite well with a corresponding nitrogen accumulation. In one case, the total amount of the three sugars was as high as 4.9% of the dry matter content in the 0-1 mm layer. It was of special interest to note that samples with high nitrogen and sugar contents also had a yellow surface colour, which probably formed during the drying process by the well-known Maillard reaction -a complex of reactions occurring when sugars and amino adds, peptides and proteins are heat-treated together.Growth of the mould fungus Penicilliurn brevicornpactum was well correlated with the content of nitrogen and low molecular carbohydrates in adjacent samples. The initial colonization was somewhat delayed in material from the outermost sapwood zone despite high nutrient contents indicating effects of antifungal compounds from the bark or toxic Maillard reaction products effective against germination. Growth of Aspergillus versicolor was likewise most elaborate on samples with the highest nitrogen and soluble carbohydrate content but the results also indicate a sensitivity to antifungal compounds present.
Rot fungi found in the exterior panelling of buildings must be able to withstand very varying conditions of temperature and moisture. In this study we have exposed wood samples with the brown-rot fungus Gloeophyllum scpiarium, often found in exterior panelling, to high and low temperatures, oxygen depletion, and drying. The activity of the fungi before and after the exposures was monitored by isothermal m icrocalori metry at 25 °C in order to assess the rate and level of recovery. The activity of the fungus was not greatly influenced by exposures (o 6, 37 and 45 °C. Higher temperatures (55 and 60°C) resulted in an initial period of low activity followed after 20-1 OOh by a recovery back to approximately the prc-exposure level. After Ih exposure to 65 °C no activity could be detected so the lethal temperature for this fungus is in the range of 60-65 °C. Low temperatures (-23 °C) resulted in reduced activity during 10-20h. The activity of the fungus decreased in closed vessels as a result of an increased concentration of carbon dioxide. When fresh air was admitted the activity wenl back to the level before the exposure. Wetting after drying returned the activity to the level it had before the drying.
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