Thesis (M.S.)--Oregon Graduate Center, 1981.

Thesis (M.S.)--Oregon State University, 1976. / Typescript (photocopy). Includes bibliographical references. Also available on the World Wide Web.

M.S. / Biochemistry / Culture parameters influencing metabolism of synthetic [superscript 14] C-labeled lignin model compounds to [superscript 14] CO2 in defined media by the fungi, Polyporus versicolor and Phanerochaete chrysosporium, were examined. Model compound metabolism was oxygen-dependent. Agitation of the cultures, resulting in formation of mycelial pellets, suppressed [superscript 14] CO2 evolution by P. chrysosporium, to a greater extent than by-P. versicolor. The concentration of nutrient nitrogen was critical; [superscript 14] CO2 evolution was retarded at 12 mM ammonium tartrate relative to 1.2 mM ammonium tartrate. Cultures evolved more [superscript 14] CO2 when grown on xylose than on either glucose or glycerol. Initial glucose at 0.1%concentration was significantly less supportive of growth and [superscript 14] CO2 evolution than cultures with 0.5-1.0% glucose. Studies with cycloheximide, a protein synthesis inhibitor, demonstrated that the lignin model compound degrading enzyme system was constitutive. 4-Methoxyl-[ [superscript 14]C] veratryl alcohol was found to be a catabolic product in the metabolism of 4-methoxyl-[ [superscript 14]C]veratrylglycerol-β-guaiacyl ether and 4-methoxyl-[ [superscript 14]C] veratric acid to [superscript 14]CO2.

M.S. / Biochemistry / The hydroxylation and cleavage of conjugated aryl olefins by horseradish peroxidase and Phanerochaete chrysosporium were investigated, and optimum incubation conditions for the enzyme reaction were developed. Substrate specificity experiments showed that the enzyme specificity corresponded roughly to that exhibited by the fungus, with the exception that P. chrysosporium also readily degraded the mono-substituted m- and p-methoxycinnamyl alcohols to their corresponding anisyl alcohols. The pathways employed by the two systems were shown to be different. [superscript 18]O tracer studies showed that the organism probably utilized the hydroxylation product as an intermediate, confirming earlier reports by other workers. (The peroxidase, however, appears to cleave the olefin directly, in addition to catalyzing the hydroxylation reaction. It is not able to cleave the hydroxylated products.) Both peroxidase and laccase purified from Polyporus versicolor incorporated labeled oxygen only onto the B-carbon of 4-0- ethylisoeugenol, whereas P. chrysosporium incorporated a significant amount at the benzylic carbon. In addition, the ability of the fungus to perform the hydroxylation reaction in the presence of catalase suggests that the phenol oxidase(s) of P. chrysosporium are not the sole catalytic agent(s) in the metabolism of lignin-related aryl olefins.

<p>Alternative sources of fuel are required worldwide, and bio-ethanol is the leading candidate. Lignocellulosic biomass, a waste component of the agricultural industry, is a promising renewable source. Due to its complex structure it is highly recalcitrant, requiring the synergistic action of a battery of enzymes to achieve complete digestion. These enzymes include cellulases, hemicellulase and the accessory enzymes acetyl xylan esterase (AXE) and ferulic acid esterase (FAE). Thermpohilic Actinomyces isolates with the ability to hydrolyze xylan were screened for esterase activity. Two isolates (ORS10 and GSIV1), identified as Streptomyces spp, were positive for AXE activity. A cosmid library representative of isolate ORS10 was composed and screened for AXE activity using -naphthyl acetate as substrate. An 18 kb cosmid clone, 18D7, tested positive for AXE activity. Intracellular fractions extracted from ORS10 were precipitated with ammonium sulphate and partially purified 161-fold. Specific activity was measured after dialysis and ion-exchange chromatography. Overall yield of the partially purified enzyme was 34 %. Two protein bands of molecular masses 40 kDa and 60 kDa have been subjected to trypsin digestion and MALDI-TOF mass spectrometry analysis. The partially purified AXE displayed optimum activity at pH 9 and at 50&deg / C. AXE activity was stable for at least 1.5 hours between 30&deg / C and 40&deg / C, and for 24 hours between pH 6-9. The kM and Vmax values were 16.93 mg/ml and 1645 units/mg enzyme, respectively. The stability of the partially purified AXE at 30&deg / C-40&deg / C suggests potential for industrial applications that utilise mesophilic fermentations.</p>

Thesis (Ph. D.)--University of Texas at Austin, 1999. / Vita. Includes bibliographical references (leaves 193-199). Available also in a digital version from Dissertation Abstracts.

Thesis (M.S.)--Oregon Graduate Center, 1979.

Thesis (M.S.)--Rutgers University, 2009. / "Graduate Program in Biology." Includes bibliographical references (p. 34-38).

Thesis (Ph. D.)--University of Florida, 1970. / Description based on print version record. Typescript. Vita. Includes bibliographical references (leaves 84-88).

Thesis (M.S.)--University of Tennessee, Knoxville, 2002. / Title from title page screen (viewed on Sept. 25, 2002). Thesis advisor: Karen W. Hughes. Document formatted into pages (vii, 58 p. : ill. (some col.)). Vita. Includes bibliographical references (p. 51-55).