Date of Award


Document Type


Degree Name

Doctor of Philosophy (PhD)


Chemical and Biomolecular Engineering

Committee Chair/Advisor

Mark A. Blenner

Committee Member

Marc R. Birtwistle

Committee Member

David A. Bruce

Committee Member

Sarah W. Harcum


Traditional chemical processes are made inefficient by the generation of side products and reactions that fail to reach completion. Bioprocesses, on the other hand, lose product potential due to the necessity of growing the organism required to produce the desired compounds. The field of metabolic engineering often seeks to alter this balance between product formation and cell growth to generate more product from the same quantity of feed (reagent). In addition to balance, such organisms may also be engineered to produce the desired products from nontraditional substrates, such as waste compounds. In resource-poor environments, the ability to produce a wanted compound from a waste material is exceptionally valuable.

One such application of this value is in human spaceflight; all needed material must be brought with the astronauts from the beginning of their trip. For short missions, this is possible, but it becomes difficult or impossible on longer missions due to substantial mass requirements. NASA’s solution to this is to produce needed supplies in situ and one method they have chosen to utilize is 3D printing. Printers have already been used to fabricate tools and components out of plastic aboard the International Space Station (ISS), however the plastic must be sent from Earth. The bioproduction of plastic in space provides one solution to this requirement by manufacturing what is needed in orbit. Polyhydroxyalkanoates (PHAs) are a class of natural, biodegradable, fully-biosynthetic polyesters. They possess varying thermal and mechanical properties on par with many petroleum-derived plastics and these properties can be manipulated by altering the monomer composition of the final PHA.

To that end, the work in this dissertation demonstrates multiple means by which the bioproduction of PHA can be carried out more efficiently, with limited resources, through metabolic engineering of the host organism. In this case, Y. lipolytica was engineered to heterologously produce PHA via exploitation of its peroxisome. Peroxisome morphology, expression systems, β-oxidation, and the greater upstream carbon metabolism of Y. lipolytica were modified. The results of these efforts serve to improve the understanding of peroxisome-associated metabolic engineering in Y. lipolytica. Application of this knowledge resulted in a doubling of PHA accumulation efficiency on the non-ideal substrate oleic acid. Finally, this work demonstrates the ability of terrestrial engineered Y. lipolytica to effectively carry out heterologous production of PHA in the hostile environment of space and identified areas of future strain health concern as targets for mitigation via synthetic biology efforts.

Available for download on Sunday, December 31, 2023