S79: Biotechnological production of long-chain dicarboxylic acids from plant oil

To overcome the current dependency on crude oil more and more polymers are produced by biotechnological processes using renewable resources as raw materials. Polymers like polyurethane, polyamide and polyesters can be produced from diols and dicarboxylic acids which are currently obtained from crude oil. Long-chain DCA are difficult and expensive to produce or are currently not available from petrochemical raw materials. Alternatively, long-chain dicarboxylic acids (DCA) can be produced by biotransformation from plant oils using yeast. These biotechnologically obtained long-chain DCA can replace conventional building blocks and provide bioplastics with new characteristics.

The most commonly used yeast strain for long-chain DCA production is the S2 classified Candida tropicalis. This strain harbors a metabolic pathway called ω-oxidation which is responsible for the conversion of fatty acids, e.g. from plant oil, to DCA.

The fermentation process for long-chain DCA production includes two phases. The first phase is an optimized cell growth phase producing high levels of biomass from a sugar substrate. The production phase is induced by pH change and addition of fatty acids. By developing different fed-batch processes we were able to obtain up to 100 g/L 1,18-Octacecendiacid from oleic acid using the genetically modified C. tropicalis strain. The process was successfully transferred to a 30 L scale.

For large scale production of long-chain DCA an S1 classified organism is required. Using homology research with the ω-oxidation pathway genes of C. tropicalis we found different non-pathogenic Pichia strains harbor similar genes and are able to perform this conversion as well.