Date of Award

12-2008

Level of Access Assigned by Author

Campus-Only Thesis

Degree Name

Master of Science (MS)

Department

Ecology and Environmental Sciences

Advisor

Jody Jellison

Second Committee Member

Seanna Annis

Third Committee Member

Bryan Dail

Abstract

Forest wood and litter decaying fungi are poorly understood despite their role in forest ecosystem function. This is particularly true of the inky cap fungi, species originally in the genus Coprinus. These fungi are common on coarse woody debris and the litter layer of forest soils however their degradative abilities haven't been adequately investigated. To characterize the wood decay potential of inky caps, ten isolates representing the genera Coprinus, Coprinopsis, and Coprinellus were studied. Growth and colony characteristics were measured on a variety of hard- and softwood substrates on agar and liquid medium and in soil block jar decay cultures. Common wood-sugar monomers and hemicellulose extracts were used as carbon substrates to investigate growth requirements and versatility of the isolates. Wood sugar composition of wood substrates before and following field and laboratory decay was characterized by HPLC. Field and laboratory degraded hardwoods were also used in decay tests to explore the role of inky caps as late stage decay fungi. In addition to wood degradative physiology, tolerances to copper-based and polycyclic aromatic hydrocarbon (PAH) compounds were measured to determine feasibility of fungal remediation of treated wood. Results of all studies were analyzed for similarities and differences both among and between species and genera. Coprinellus species were typically the fastest growing, and were the only isolates to decay wood blocks without pre-treatment. Poplar was the preferred substrate, with other hardwood species decayed to a lesser extent. Preference for poplar is supported by the resultant increase in biomass production when Coprinellus were cultured in media amended with sugars abundant in hardwood hemicellulose, and failure to grow on media amended with softwood hemicellulose sugars. Radial growth rates were not correlated with liquid culture biomass production, however a stress reaction, a known strategy for late stage decay fungi, is evident as cultures appeared abnormal with reduced biomass on softwood sugars while growth rate increased. All isolates produced higher weight losses following brown rot decay compared to non-previously decayed controls. Coprinellus radians isolates produced the greatest weight losses following four or more years of field decay and also had greater degradative capabilities following white rot decay compared to untreated controls. Increased losses in wood weight in the late stage decay experiments could not be attributed solely to wood sugar levels and lignin chemistry and physical changes to the wood structure were likely involved. None of the tested isolates showed tolerance to copper or copper-based wood preservatives. Observed tolerance to PAH preservatives was ambiguous, as some inky cap fungi demonstrated ability to grow in the presence of these compounds in various Petri dish cultures, but no ability to decay PAH treated wood blocks. This research suggests that some inky cap fungi, in particular Coprinellus isolates, are effective at degrading hardwoods and that all may be capable of late stage decay in the natural environment. Though further study of additional isolates is needed, this work highlights distinct physiological differences between the genera and isolates of different species.

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