No description available.

Tang, Xiaoju. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 66-71). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

by Kit Sing Au. / Bibliography: leaves 283-326 / Thesis (M.Ph.)--Chinese University of Hong Kong, 1984

Lignocellulose is one of the most abundant carbon sources in nature. This naturally-occuring substance is an underutilized source of bioenergy. A major bottleneck in biofuel processing is the enzymatic hydrolysis of lignocellulose into its ultimate fermentable product, glucose. Cellulomonas fimi is a well-studied soil organism known for its capabilities to efficiently hydrolyze cellulose. Recently sequenced genomes of Cellulomonas fimi and Cellulomonas flavigena have allowed analysis to reveal previously unidentified cellulases from several glycoside hydrolase (GH) families. This study also includes the expression of secreted cellulases from families GH 5, 6, and 9 at the protein level by the native organism after growth in media supplemented with carboxymethylcellulose or soluble xylan. In order to find enzymes with novel qualities, the cloning and expression of these newly identified cellulases from C. fimi and C. flavigena were done. One of these enzymes is Celf_1230 (Cel6C), a putative cellobiohydrolase from the glycoside hydrolase family 6. Using substituted cellulose derivatives as substrates, we have characterized Celf_1230 to be a thermostable enzyme with endoglucanase activity.

No description available.

Lignocellulose is one of the most abundant carbon sources in nature. This naturally-occuring substance is an underutilized source of bioenergy. A major bottleneck in biofuel processing is the enzymatic hydrolysis of lignocellulose into its ultimate fermentable product, glucose. Cellulomonas fimi is a well-studied soil organism known for its capabilities to efficiently hydrolyze cellulose. Recently sequenced genomes of Cellulomonas fimi and Cellulomonas flavigena have allowed analysis to reveal previously unidentified cellulases from several glycoside hydrolase (GH) families. This study also includes the expression of secreted cellulases from families GH 5, 6, and 9 at the protein level by the native organism after growth in media supplemented with carboxymethylcellulose or soluble xylan. In order to find enzymes with novel qualities, the cloning and expression of these newly identified cellulases from C. fimi and C. flavigena were done. One of these enzymes is Celf_1230 (Cel6C), a putative cellobiohydrolase from the glycoside hydrolase family 6. Using substituted cellulose derivatives as substrates, we have characterized Celf_1230 to be a thermostable enzyme with endoglucanase activity.

No description available.

No description available.

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

Graduation date: 1994