11-04: Engineering Candida tropicalis to produce adipic acid from renewable oils

Adipic acid is an important industrial chemical used to make Nylon 6,6 and polyurethane resins.  It is currently produced from petrochemical sources with an estimated global market of 5 billion pounds per year. The production of adipic acid from renewable sources would allow the production of completely bio-based nylons and polyurethanes.  To this end, we have engineered the diploid yeast Candida tropicalis to produce adipic acid from plant-based oils.  C. tropicalis can normally grow on alkanes or fatty acids as the sole carbon source via cyclic degradation through its β-oxidation pathway. A strain in which the β-oxidation pathway has been completely blocked can convert these substrates at high yield and selectivity to the corresponding dicarboxylic acids via the omega-oxidation pathway (Picataggio et al., 1992), producing diacids with a mixed chain-length distribution that precisely mimics the plant-based oil feedstock. We have since engineered both the beta-oxidation and omega-oxidation pathways to enable selective production of adipic acid from any plant-based oil, regardless of its fatty acid composition.