Microcalorimetric Characterization of the Recovery of a Brown-Rot Fungus after Exposures to High and Low Temperature, Oxygen Depletion, and Drying

Abstract

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.

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

“…It was estimated that anabolic metabolism contributed 1.5% to the total heat production for oxic growth of yeast and bacteria and 8% for anoxic growth (Belaich 1980 ; Larsson et al 1991 ). The released heat is proportional to the consumption of nutrients as long as the mode of metabolism does not change (Xie et al 1997 ). This technique has been used previously to determine the microbial activity in soils (Vor et al 2002 ; Dyckmans et al 2006 ) and of yeasts (Ölz et al 1993 ).…”

“…This technique has been used previously to determine the microbial activity in soils (Vor et al 2002 ; Dyckmans et al 2006 ) and of yeasts (Ölz et al 1993 ). Only a few studies describe the use of micro-calorimetry to determine the physiological activity of rotting fungi (Ginterova and Lazariva 1989 ; Xie et al 1997 ; Bjurman and Wadso 2000 ). Heat production caused by fungi in an infected wood block can be directly related to the mass loss of the same block; for total esterase activity (TEA) determination, however, the wood samples need to be crushed and degradation products leach out during the test in aqueous solution.…”

Morphological Characterization and Quantification of the Mycelial Growth of the Brown-Rot Fungus Postia placenta for Modeling Purposes

“…Apart from the biochemical aspect, the environmental factors, (e.g. temperature, moisture content, and oxygen depletion), that influence its growth rate in wood, have also been studied [ 28 – 30 ]. However, to our knowledge, there are no publications reporting the visualization of mycelial structures and quantitative measurement of growth characteristics of Postia placenta at the microscopic scale.…”

The activity of rot fungi (Postia placenta) during drying and rewetting cycles measured by isothermal calorimetry

“…In this study, we investigate if isothermal calorimetry can be used to monitor the fungal activity of a brown rot fungus ( Postia placenta ) when grown at different MCs, and how changes in MC influence the activity. One of us (LW) has previously used similar techniques to assess the influence of relative humidity on mold activity , the response of a brown rot fungi after exposures to high and low temperatures, oxygen depletion, and drying , and temperature on fungal growth .…”