Ultrastructural, immunocytochemical and UV absorption spectroscopy techniques were used to elucidate the progressive changes that occur within woody cell walls during decay by Ceriporiopsis subvermispora. After only 2 weeks of incubation, uranyl acetate staining revealed a diffuse electron dense zone in the secondary wall near hyphae and around the outer circumference of the wall. The extent of cell wall staining increased with longer fungal incubation. No staining occurred in sound unaltered cell walls. Proteins of varying molecular weights (insulin, 5730 Da; myoglobin, 17600 Da; ovalbumin, 44287 Da) were infiltrated into sound and decayed wood followed by immunogold labelling and transmission electron microscopy. Insulin readily penetrated into the outer most regions of secondary walls of wood cells after 2 weeks of decay. Myoglobin was first observed to penetrate cell walls at 4 weeks of degradation and ovalbumin was found after 8 weeks in wood with advanced stages of decay where extensive cell wall disruption was evident. None of the proteins used were localized within cell walls of untreated, control wood samples. UV microspectrophotometry demonstrated a progressive loss of absorbance at 240 and 280 nm within the secondary walls and middle lamellae at various sampling times throughout the duration of the decay study.
Bibliographical noteFunding Information:
Published as paper no. 22 548 of the contribution series of the Minnesota Agricultural Experiment Station based on research conducted under Project 22-69H. This research was supported in part by the Biopulping Consortium consisting of member companies involved in pulp and paper production and associated fields; the USDA Forest Products Laboratory, Madison, Wisconsin; Biotechnology Center, University of Wisconsin and Department of Plant Pathology, University of Minnesota. The authors thank Dr T. Kent Kirk and colleagues at the Institute of Microbial and Biochemical Technology, USDA Forest Products Laboratory for their support and advise during this study.
- Lignin degrading enzymes
- White rot
- Wood decay