Dissertation
ENGINEERING MICROBIAL AND ALGAL PLATFORMS FOR SUSTAINABLE BIOPLASTIC AND BIOMASS PRODUCTION FROM WASTE-DERIVED SUBSTRATES
Washington State University
Doctor of Philosophy (PhD), Washington State University
05/2025
DOI:
https://doi.org/10.7273/000007485
Abstract
The increasing environmental concerns associated with fossil-based plastics have driven the search for sustainable alternatives, with polyhydroxybutyrate (PHB) emerging as a promising class of biodegradable bioplastics. However, high production costs and substrate limitations hinder their large-scale application. This dissertation primarily explores the metabolic engineering of Yarrowia lipolytica to enhance PHB production through lipogenesis pathway redirection, using low-cost, sustainable substrates including acetate and xylose.
Three core objectives are addressed: (1) redirecting the lipogenesis pathway toward PHB biosynthesis via compartmentalized metabolic engineering and gene dosage optimization, (2) enabling Y. lipolytica to metabolize xylose efficiently for improved biopolymer yield and cell growth, and (3) optimizing fermentation conditions and developing a kinetic model for microbial growth and substrate consumption under acetate-glucose co-substrate scenarios. Engineered strains demonstrated enhanced PHB accumulation and improved growth on xylose, with acetate co-feeding mitigating redox and energy limitations.
In parallel, a black-box kinetic model was developed to predict Chlorella vulgaris growth and nutrient uptake dynamics under mixotrophic conditions. This separate line of work informs future system-level design in sustainable bioprocessing, particularly for nutrient utilization in algal systems. Together, these studies contribute independently to advancing microbial and algal biotechnology platforms for sustainable production of bioplastics and biomass.
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Details
- Title
- ENGINEERING MICROBIAL AND ALGAL PLATFORMS FOR SUSTAINABLE BIOPLASTIC AND BIOMASS PRODUCTION FROM WASTE-DERIVED SUBSTRATES
- Creators
- Masoud Tourang
- Contributors
- Shulin Chen (Chair)Manuel Garcia-Perez (Committee Member)Shyam S Sablani (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Department of Biological Systems Engineering
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Publisher
- Washington State University
- Number of pages
- 183
- Identifiers
- 99901221150701842
- Language
- English
- Resource Type
- Dissertation