Carbon conversion efficiency and 13C labeling of the tricarboxylic acid cycle in lesquerella

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Lesquerella (Physaria fendleri) is a Brassicaceae that produces a valuable class of compounds in its embryos called hydroxy fatty acids. These fatty acids are used widely in industry to produce cosmetics, coatings, greases, plastics, paints, and biofuel, among others. The current source of hydroxy fatty acids is ricinoleic acid from the castor plant (Ricinus communis), which also produces the highly toxic compound ricin that has eliminated castor plant cultivation in the United States. Lesquerella produces lesquerolic acid, a hydroxy fatty acid with only two additional carbons as compared to ricinoleic acid, which therefore performs in a chemically similar manner. Since it is non-toxic and already grows in the wild in the southwest US as a winter annual that will not compete with food crops, lesquerella could serve as a suitable alternative to castor oil. However to become economically viable, lesquerella first must be engineered to produce more of these fatty acids to meet demands. The most recent work done towards meeting this end goal is: (i) quantifying the development of the biomass components of lesquerella embryos in planta (fatty acids, starch, protein, and cell wall); (ii) identifying culture conditions for growing embryos in vitro so that their biomass composition matches that of embryos grown in planta; (iii) calculating the rates of substrate consumption by embryos; iv) determining the efficiency at which carbon is converted into biomass; and (v) quantifying the percentage of total labeling within the tricarboxylic acid cycle of 13C-labeled embryos. Further labeling results are in process by performing 13C-based metabolic flux analysis, an approach that will quantify rates of intermediate product formation in the rest of the embryo central metabolism and identify the limiting steps in fatty acid production.


Biological Sciences: 1st Place (The Ohio State University Denman Undergraduate Research Forum)


physaria fendleri, lesquerella, metabolic engineering, 13C labeling, tricarboxylic acid cycle, carbon conversion efficiency