Glucose isomerase (GI) catalyzes the conversion of D-glucose to D-fructose in vitro. It is one of the bulkiest commercial enzymes, essential for the mass production of high-fructose corn syrup (HFCS) and crystalline fructose. / In this study, the effects of nitrogen sources, carbon sources, expression vectors, host strains, bacterial (Vitreoscilla) hemoglobin, selective pressure, plasmid stability and fermentation process on the GI production were investigated. The results showed that E. coli could express cloned thermostable GI at high expression level. E. coli transformed with the recombinant plasmid P-lac-GI gave the best result in term of total GI production and expression level. Corn steep liquor could be used as a cheap alternative nitrogen source for what was in LB medium. The concentration of glucose affected the expression level of GI significantly. Replacement of the ampicillin resistance gene by kanamycin resistance gene improved the plasmid stability leading to high productivity of GI in fed-batch fermentation. A suicide system could further improve the plasmid stability resulting in a high productivity of GI. A feeding strategy for fed-batch fermentation with the optimized parameters was developed to result in the production of up to 3g/L recombinant GI, which constituted 50% of the total soluble proteins. The total yield was 5-fold higher than that from flask experiments and 7-fold higher than the highest ever recorded. The expression level was also 100% higher than it was in other reports. / Liu Zhaoming. / "August 2005." / Advisers: J. Wang; W. P. Fong. / Source: Dissertation Abstracts International, Volume: 67-07, Section: B, page: 3780. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (p. 129-154). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract in English and Chinese. / School code: 1307.
| Identifer | oai:union.ndltd.org:cuhk.edu.hk/oai:cuhk-dr:cuhk_343671 |
| Date | January 2005 |
| Contributors | Liu, Zhaoming, Chinese University of Hong Kong Graduate School. Division of Biochemistry. |
| Source Sets | The Chinese University of Hong Kong |
| Language | English, Chinese |
| Detected Language | English |
| Type | Text, theses |
| Format | electronic resource, microform, microfiche, 1 online resource (xix, 154 p. : ill.) |
| Rights | Use of this resource is governed by the terms and conditions of the Creative Commons “Attribution-NonCommercial-NoDerivatives 4.0 International” License (http://creativecommons.org/licenses/by-nc-nd/4.0/) |
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