Wood Decay by the White-Rotting Basidiomycete Physisporinus vitreus from a Cooling Tower

Abstract

KeywordsBasidiomycetes in cooling towers Physisporinus vitreus Decay of water-saturated specimens Micromorphology Manganese deposits Lignin degradation SummaryTimbers in cooling towers are mainly attacked by soft rot causing fungi which belong to Ascomycetes and Deuteromycetes. The basidiomycete Physisporinus vitreus degraded water-saturated timber as fibrous white-pocket rot in a cooling tower in which water treatment had been changed from chlorine to ozone. In the laboratory, the fungus revealed a remarkable wood decay pattern. In crosswise piled, water-saturated pine specimens it attacked only those parts not surrounded by air. The decay occurred as small longish delignified white pockets, preferentially in the earlywood. Transmission electron microscopy of unstained sections showed some electron density in the hyphal extracellular layer and in the wood cell wall beneath a hypha. Contrasted with KMnO 4 staining, these regions became more pronounced which may indicate presence of lignin degradation products. UV-microspectrophotometry of these areas exhibited an increased absorbance. Many decay pockets were black due to manganese (Mn) deposits. Mn determination by inductively coupled plasma emission (ICP) revealed up to 518ppm Mn. TEM/EDXA showed Mn deposits in the hyphal extracellular layer, on the cell wall surface and in the inner S 2 layer beneath a hypha. The Mn may be related to the lignin attacking peroxidases.

Critical moisture conditions for fungal decay of modified wood by basidiomycetes as detected by pile tests

“…Pile tests: The decay test with piled wood specimens was described by Ammer (1964), Schmidt et al (1996Schmidt et al ( , 1997, and Stienen et al (2014). This method ( Figure 1a) allowed for determining the cardinal points of wood MC for different fungal species and wood-based substrates in terms of mycelial growth and decay activity (Huckfeldt et al 2005;Huckfeldt and Schmidt 2006).…”

Permeability changes in heartwood of Picea abies and Abies alba induced by incubation with Physisporinus vitreus

“…The white rot fungus Physisporinus vitreus is an exception in this regard; it preferentially degrades the pit membranes of bordered pits in the heartwood of conifers under controlled conditions, and causes only negligible mass losses (Schwarze and Landmesser 2000). This fungus is, however, capable of strongly degrading water-saturated timber in cooling towers (Schmidt et al 1996(Schmidt et al , 1997.…”

Physisporinus vitreus: a versatile white rot fungus for engineering value-added wood products

“…Interestingly, P. vitreus decomposes water-saturated timber in cooling towers by a fibrous, white pocket rot (Van Acker et al 1995;Schmidt et al 1996Schmidt et al , 1997Schmidt 2007). In the laboratory, the fungus reveals a remarkable pattern of colonization.…”

“…In the laboratory, the fungus reveals a remarkable pattern of colonization. In crosswise piled water-saturated pine wood, the fungus decomposes only those parts of the substrate not surrounded by air (Schmidt et al 1996(Schmidt et al , 1997. Some isolates of this fungus have an extraordinary capacity to induce significant permeability changes in the heartwood of Norway spruce and silver fir after hydrolysis of bordered pit membranes without causing significant loss of wood strength (Schwarze et al 2006).…”