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https://hdl.handle.net/2142/125690
Description
Title
Biomass conversion in oleaginous yeasts
Author(s)
Woodruff, William
Issue Date
2024-07-03
Director of Research (if dissertation) or Advisor (if thesis)
Rao, Christopher V
Doctoral Committee Chair(s)
Rao, Christopher V
Committee Member(s)
Zhao, Huimin
Jin, Yong-Su
Shukla, Diwakar
Department of Study
Chemical & Biomolecular Engr
Discipline
Chemical Engineering
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Oleaginous Yeast
Biomass Hydrolysate
Bioreactors
Rhodosporidium Toruloides
Yarrowia Lipolytica
Lipids
Fatty Alcohols
Transcriptomics
Adaptive Evolution
Metabolic Engineering
Language
eng
Abstract
The conversion of lignocellulosic biomass into fuels and chemicals represents a key step in the development of sustainable replacements for petrochemical resources. Microorganisms such as the oleaginous yeasts Rhodosporidium toruloides and Yarrowia lipolytica can produce lipids suitable for biodiesel production or as a substitute for palm and other plant-based oils when grown on biomass-derived substrates. Through metabolic engineering, additional value-added oleochemicals such as fatty alcohols can also be produced by these yeasts. This dissertation describes a series of projects exploring bioprocess development, transcriptomic, and metabolic engineering approaches to improving growth and lipid production from biomass substrates in oleaginous yeasts. Firstly, the growth of R. toruloides on sorghum biomass hydrolysate was optimized, limiting nutrients were identified through growth on synthetic hydrolysate equivalents, and an adaptive laboratory evolution study was performed to develop strains with enhanced substrate utilization capacity and identify relevant mutations. Next, growth of an engineered strain of R. toruloides with enhanced intracellular lipid accumulation was optimized on sorghum and oilcane hydrolysate in laboratory-scale bioreactors. Lipid production and downstream extraction was then scaled-up in a 75 L pilot reactor at the Integrated Bioprocessing Research Laboratory. Subsequent chapters describe a transcriptomic study of nitrogen metabolism in the model yeast Saccharomyces cerevisiae which relates to the mechanism of lipid accumulation in oleaginous yeasts and the preliminary results of two ongoing studies: the transcriptomic analysis of growth on sorghum hydrolysate in R. toruloides and the development of engineered Y. lipolytica strains capable of producing fatty acids from plant-derived oils. The results of these studies demonstrate the potential for microbial oil and value-added chemical production from a variety of biomass substrates in non-model yeasts. While R. toruloides has higher native lipid titers and utilizes all carbon sources present in biomass hydrolysate, making it suitable for scale-up of triacylglycerol production from these substrates, Y. lipolytica is more amenable to engineering with existing genetic tools for production of high-value compounds and can utilize a variety of nonpolar substrates, including oils from plant or waste sources. Ultimately, through careful selection of microbial hosts and subsequent bioprocess optimization, sustainable replacements for petrochemicals and fuels can be generated.
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