Thesis (Ph. D.)--Washington University, St. Louis. / Cover title. Reprinted from the 17th annual report of the Missouri botanical garden.

Thesis (M.S.), Oregon Graduate Center, 1980.

Thesis (doctoral)--Swedish University of Agricultural Sciences, 2006. / Thesis documentation sheet inserted. Errata sheet inserted. Appendix reprints four papers and manuscripts co-authored with others. Includes bibliographical references. Issued also electronically via World Wide Web in PDF format; online version lacks appendix.

M.S. / Biochemistry / The white-rot basidiomycete Phanerochaete chrysosporium produces intracellular soluble and particulate ß-glucosidases and an extracellular ß-glucosidase. The extracellular enzyme is induced by cellulose but repressed in the presence of glucose. The molecular weight of this enzyme is 90,000. The K [subscript m] for -p-nitrophenyl-ß-glucoside is 1.6 x 10[superscript -4] M; the K [subscript 1] for glucose, a competitive inhibitor, is 5.0 x 10[superscript -4] M. The K [subscript m] for cellobiose is 5.3 x 10[superscript -4] M. The intracellular soluble enzyme is induced by cellobiose; this induction is prevented by cycloheximide. The presence of 300 mM glucose in the medium, however, had no effect on induction. The K [subscript m] for p-nitrophenyl- ß -glucoside is 1.1 x 10[superscript -4] M. The molecular weight of this enzyme is about 410,000. Both enzymes have an optimal temperature of 60°C and an E [subscript act] of 9.15 kcal/mole. The pH optima, however, were 7.0 and 5.5 for the intracellular and extracellular enzymes, respectively.

Comparisons were made between the sensitivities of unique ‘wild’ isolates and domestic isolates of the dry rot fungus, <i>Serpula lacrymans</i>, to temperature, water potential and pH. Comparisons were also made between their capacities of timber decay. The ‘wild’ Himalayan isolates displayed slightly less marked sensitivities to high and low temperature and lowered water potential, yet the isolates were equally tolerant of pH. In general, the linear growth rates of the domestic isolates proved to be twice those of the ‘wild’ Himalayan set, whereas little variation occurred between their rates of timber decay. This study also resulted in the first isolation and reliable identification of ‘wild-growing’ <i>S. lacrymans</i> collected in Europe. The main part of the project involved the construction of novel chambers in order to examine the effects of lowered humidity and moving air flow on the activity of <i>S. lacrymans</i>. In the smallest and simplest of these, its growth and timberdecaying activities could be stopped by incubation at 86% relative humidity or by the application of a pumped air flow rate of 2.5 litres per minute; however, <i>S. lacrymans</i> was not inactivated until more-stressful conditions were applied. In addition, an intermediate rate of air flow provoked marked directional growth away from the stress. Furthermore, the introduction of stone, brick and plaster into these models encouraged the capacities of timber decay and mycelial growth. The use of a larger and more representative model incorporating simulated flooring and plaster walling within glass tanks revealed differences in the appearances and patterns of colonisation by <i>S. lacrymans</i> depending upon whether aged or new materials were used. Treatments involving air drying by fans caused both a shrivelling and a loss of viability of the fungus only when there was no ‘reservoir’ of water available; when there was water present, latent activity remained. An elaboration of this experimental design tested the effects of a combined biological and environmental treatment. Subsequently, the application of <i>Trichoderma harzianum</i>, a known antagonist of <i>S. lacrymans</i>, proved not to be an effective remedial treatment on its own, but appeared to impart a mildly protective effect when combined with a drying regime. Importantly, in the latter situation <i>T. harzianum</i> caused a severe degradation of the part of the colony responsible for the uptake of water in <i>S. lacrymans</i>. Another workshop-scale model simulating more authentically a damp sub-floor space and a cavity behind aged plaster walling was developed. When respective treatments by fan drying and passive ventilation were compared, the former were more effective, but its efficacy could be augmented by incorporating low-level passive ventilation via discreet vents. In this manner, a successful remedial treatment of <i>S. lacrymans</i> could be effected, though the prevalence of mould could prove to be undesirable in practice. However, some samples of this displayed antagonistic effects against <i>S. lacrymans</i>. A further experiment was designed to test the effects of air drying on the production of the stress-protective carbohydrate trehalose and of some associated solutes by <i>S. lacrymans</i>. In contrast to reports of some other organisms, no definite stockpiling of any of the compounds occurred. A final series of experiments revealed that <i>S. lacrymans</i> removed calcium, silicon and iron from sandstone and calcium, sulphur and iron from aged plaster; these elements were sequestered on its hyphae, especially in the form of calcium oxalate. Degradation of the sandstone was implicit but not obvious microscopically. Furthermore, <i>S. lacrymans</i> transported iron from these building materials through its mycelial system. An attempt to determine the effects of separate minerals in sandstone and plaster on timber decay revealed few variations.

No description available.

Thesis (Ph.D. Biological Sciences)--University of Waikato, 2007. / Includes bibliographical references (p. 409-439) Also available via the World Wide Web.

Thesis (M.S.)--Oregon State University, 1996. / Typescript (photocopy). Includes bibliographical references (leaves 108-123). Also available on the World Wide Web.

Thesis (doctoral)--Swedish University of Agricultural Sciences, 2004. / Thesis documentation sheet inserted. Appendix reprints four papers and manuscripts co-authored with others. Includes bibliographical references. Also partially issued electronically via World Wide Web in PDF format; online version lacks appendix .

Thesis (Ph. D.)--Universität Göttingen, 2003. / Includes bibliographical references.