Metabolic Engineering for Lignin Valorization and Martian In Situ Resource Utilization
Kruyer, Nicholas S.
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Metabolic engineering is a vital tool to help move away from petroleum dependence in chemical production. By taking advantage of native and engineered metabolic pathways in readily culturable microorganisms, we can produce many of the compounds we need renewably and sustainably. Towards this, this thesis first studied the use of metabolic engineering for the production of the commodity chemical adipic acid. A literature review of metabolic pathways towards adipic acid showed distinct advantages to using lignin-derived aromatics as the starting material. To further explore this, Escherichia coli was engineered to produce adipic acid from the lignin derived monomer, catechol, and novel branched adipic acid analogs from alkyl-substituted catechols, providing insight into the substrate specificity and activity of pathway enzymes. Apart from lignin, carbon dioxide is also a promising non-sugar feedstock, allowing for application of metabolic engineering in extreme environments. To further explore this, a biotechnology-enabled process for the production of 2,3-butanediol from Martian CO2 was designed using cyanobacteria to fix the CO2 into sugars and an engineered E. coli to convert the sugars into 2,3-BDO. Process analysis highlighted biological and material improvement targets for increasing feasibility of Martian application, as well as the distinct advantage in O2 production that is gained using a biotechnology-enabled process. Finally, this work reviews the use of cell-free systems (CFSs) for the production of chemicals, energy, and therapeutics, highlighting recent advancements in production of membrane proteins in CFSs. In summary, this thesis provides a multi-level view and analysis of metabolic engineering applications for renewable chemical production.