Molecular weight modulation in polyhydroxybutyrate fermentations
Name
166330284-MIT.pdf
Description
Full printable version
Size
7.55 MB
Format
Adobe PDF
Checksum (MD5)
00d5d61f093ffbe88614f7b315dea4ef
Author(s)
Waters, Benjamin Ragan
Advisor(s)
Charles L. Cooney.
Alternative Title
Molecular weight modulation in PHB fermentations
Date Issued
2007
Publisher
Massachusetts Institute of Technology
Abstract
Polyhydroxybutyrate (PHB) is a material with significant potential for commercial applications. It has material properties similar to isotactic polypropylene; it can be produced from renewable resources; it is biodegradable. Unfortunately, it is very brittle when compared to polypropylene. The physical property that most significantly affects elastic behavior is molecular weight. In an effort to understand how molecular weight is formed in PHB production, kinetic studies of PHB fermentations have been performed using fermentation conditions which allow biomass growth and PHB production phases to be separated. These data indicate that molecular weight increases very quickly and then remains fairly constant in PHB fermentations. Additional studies have indicated that only slight changes in molecular weight can be caused by changing fermentation process conditions or using mutants of the polymerization enzyme. Additionally, one mutant polymerization enzyme has been shown to excrete moderate levels of PHB monomer, 3-hydroxybutyrate, into the fermentation media. This may have application in achieving synthetic production of PHB.
Description
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, June 2007.
Includes bibliographical references.
Subjects
Chemical Engineering.
MIT Department
Massachusetts Institute of Technology. Department of Chemical Engineering
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