Development of new biocatalysts and process optimization for the production of long-chain a,o-dicarboxylic acids
Introduction: a,o-dicarboxylic acids (DCA) are versatile chemical intermediates of different chain length used as raw materials for the preparation of parfums, polymers, or adhesives. The majority of industrial short chained DCA production is based on chemical conversion from petrochemical raw materials. However, chemical synthesis of long-chain DCA (>13 C atoms) is challenging and expensive. An alternative to chemical synthesis is the biotechnological production of DCA from renewable resources. Some microorganisms, like yeasts of the genus Candida, are able to oxidize long-chain, unsaturated alkanes or saturated and unsaturated fatty acids at the terminus and convert them selectively to 􀄮,􀈦-dicarboxylic acids. Objectives: Our aim is the process optimization for the production of long-chain DCA with Candida tropicalis and the development of new biocatalysts via metabolic engineering. Methods: We investigated growth and production parameters for the bioconversion of fatty acids into diacids with C. tropicalis. In parallel, we screened for alternative microbial biocatalysts and have started with targeted metabolic engineering. Results: We could improve the fermentative production process of 1,18- octadecenoic diacid with C. tropicalis. In addition we demonstrated the conversion of several renewable resources (fatty acids or fatty acid methylesters) into diacids. Also, we identified Pichia guilliermondii as potential new DCA-producer. Conclusion: C. tropicalis is an optimized biocatalyst for DCA production with a broad substrate spectrum and high production yields. However, industrial usage of C. tropicalis is hindered because of its BSL-2 status in Europe. New BSL-1 biocatalysts like P. guilliermondii have to be genetically improved via metabolic engineering.