The influence of substrate and enzyme concentration on the rate of saccharification of two defined, insoluble, cellulose substrates, Avicel and Solka-Floc, by the cellulase enzyme system of Trichoderma viride has been evaluated. Assays utilized enzyme concentrations ranging from 0.014 to 0.056 filter paper unit per mL and substrate concentrations up to 10% (w/v). Analysis by initial velocity methods found the maximum velocity of the enzyme to be nearly equivalent for the two substrates and the km for the two substrates to be of similar magnitude, i.e., 0.20% for Solka-Floc and 0.63% for Avicel (w/v). Studies utilizing relatively high substrate concentrations (greater than 15 times the Km) demonstrated that the enzyme exhibits very different apparent substrate inhibition properties for the two substrates. The rate of saccharification of Avicel at relatively high substrate concentrations was up to 35% lower than the maximum rate which was obtained at a lower substrate concentration. The Avicel concentration corresponding to the maximum rate of saccharification was dependent on enzyme concentration. In contrast to the results with Avicel, the enzyme did not exhibit substrate inhibition with the Solka-Floc substrate. Potential differences in the degree of substrate inhibition with different substrates, as reported in this paper, is particularly relevant to the experimental design of comparative studies. / Graduation date: 1990

Triclosan, a synthetic antimicrobial agent, is an emerging environmental contaminant. Due to incomplete removal of triclosan by wastewater treatment plants, treated wastewater is one major source of environmental triclosan. Biodegradation of triclosan has been observed in activated sludge and the environment, suggesting that it is possible to develop a cost-effective biotreatment strategy for triclosan removal from wastewater. However, current knowledge on triclosan biodegradation is scarce and limited. To bridge this knowledge gap, this dissertation characterized cultivable triclosan-degrading microorganisms, identified uncultivable triclosan-utilizing bacteria, and elucidated triclosan biodegradation pathways. Furthermore, two treatment strategies were examined to enhance triclosan biodegradation in nitrifying activated sludge (NAS). A wastewater bacterial isolate, Sphingopyxis strain KCY1 (hereafter referred as strain KCY1), can completely degrade triclosan with a stoichiometric release of chloride. This strain can retain its degradation ability toward triclosan when after grown in complex nutrient medium containing triclosan as low as 5 micrograms/L. Based on five identified metabolites, a meta-cleavage pathway was proposed for triclosan biodegradation by strain KCY1. By using [13C12]-triclosan stable isotope probing, eleven uncultured triclosan-utilizing bacteria in a triclosan-degrading microbial consortium were identified. These clones are distributed among alpha-, beta-, or gamma-Proteobacteria, suggesting that triclosan-utilizing bacteria are phylogenetically diverse. None of these clone sequences were similar to known triclosan degraders. Growth substrates affected the triclosan degradation potential of four selected oxygenase-expressing bacteria. Biphenyl-grown Burkholderia xenovorans LB400 and propane-grown Rhodococcus ruber ENV425 cannot degrade triclosan. On the other hand, propane- and 2-propanol-grown Mycobacterium vaccae JOB5 can degrade triclosan completely. Due to product toxicity, finite transformation capacities for triclosan were observed for Rhodococcus jostii RHA1 grown on biphenyl, propane, and LB medium with dicyclopropylketone (alkane monooxygenase inducer). Four chlorinated metabolites were detected during triclosan degradation by biphenyl-grown RHA1 and a meta-cleavage pathway was proposed. Complete triclosan (5 mg/L) degradation was observed within 96 hrs in NAS receiving ammonia amendment (0 to 75 mg/L of NH4-N). The fastest triclosan degradation was observed in the NAS exhibiting the highest amount of ammonia. When ammonia oxidation was active in NAS, the amendment of strain KCY1 did not further enhance triclosan removal. Overall, the results suggested that triclosan biodegradation can be enhanced by increasing the activity of ammonia oxidation in NAS.

Bibliography: leaves 134-148. / xi, 148 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / The objectives of this study are to determine if and how inorganic matrices influence organic matter decomposition with particular emphasis on the biochemical changes which occur as decomposition progresses. The influence of inorganic matrices (sand, sand + kaolin and loamy sand) on the decomposition of straw and Eucalyptus litter during incubations was followed by various chemical and spectroscopic methods to aid in the understanding of the mechanism of physical protection of organic matter in soils. / Thesis (Ph.D.)--University of Adelaide, Dept. of Soil Science, 1997

Erratum pasted inside back end paper. / Bibliography: leaves 174-201. / xvii, 202, [77] leaves, [8] leaves of plates : ill. (chiefly col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Establishes that the herbicide carbetamide degrades rapidly upon repeated application to soil, when compared to a previously untreated soil. / Thesis (Ph.D.)--University of Adelaide, Dept. of Crop Protection, 1997

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1990. / Vita. Abstract. Includes bibliographical references (leaves 80-85). Also available via the Internet.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1992. / Vita. Abstract. Includes bibliographical references (leaves 77-80). Also available via the Internet.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1992. / Vita. Abstract. Includes bibliographical references (leaves 71-73). Also available via the Internet.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1991. / Vita. Abstract. Includes bibliographical references (leaves 76-82). Also available via the Internet.

Thesis (M.A.)--University of Alberta, 2010. / Title from pdf file main screen (viewed July 27, 2010). "A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Master of Arts, Anthropology". Includes bibliographical references.

Thesis (M. Sc.)--University of Hong Kong, 2006.