Biotechnological Production of Fumaric Acid by Rhizopus arrhizus—Reaching Industrially Relevant Final Titers

Abstract

Fumaric acid is used in various areas of the chemical industry due to its functional groups. For example, it is used in the polymer industry to produce unsaturated polyester resins, which are nowadays mostly produced from fossil raw materials. With regard to sustainable biotechnological fumaric acid production, the main challenge is to develop a cost-effective and robust fermentation process with industrially relevant final titers, productivities and yields. For biotechnological fumaric acid production, mainly fungi of the genus Rhizopus are used, which require very complex and challenging morphology control. The aim of this work is the development of an effective biotechnological fumaric acid production process with R. arrhizus NRRL 1526. Significant insights into the morphology control of the fungus and optimization of production characteristics were obtained, and a final titer of 86.3 g/L fumaric acid was achieved in a batch cultivation, with a yield of 0.67 g/g and a productivity of 0.60 g/(L∙h). In addition, a fed-batch process was developed, in which the production phase was extended, and a maximum final titer of 195.4 g/L fumaric acid was achieved. According to current knowledge, this value is the highest final concentration of fumaric acid produced using biotechnology.