Fumaric Acid

Abstract

Fumaric acid is an important specialty chemical with wide industrial applications ranging from its use as feedstock for the synthesis of polymeric resins to acidulant in foods and pharmaceuticals. Currently, fumaric acid is mainly produced by petroleum-based chemical synthesis. Limited petroleum resources, rising oil prices, and heightened environmental concerns about chemical synthesis have prompted interest in the development of bio-based fumaric acid from renewable resources. Filamentous fungal fermentation with Rhizopus spp. can produce fumaric acid from glucose via a reductive tricarboxylic acid (TCA) pathway and was once used commercially before the rise of the petrochemical industry. However, conventional fumaric acid fermentation is expensive because of its low product yield and productivity. Filamentous fungal fermentation is also difficult to operate because of cell morphology. Methods to control cell growth in the pellet form and to immobilize the mycelia in biofilm have been developed to improve fermentation performance. In this chapter, we provide detailed discussions on fumaric acid producing microorganisms (mainly Rhizopus oryzae); the metabolic pathway and key enzymes involved in fumaric acid overproduction; other genetically modified organisms developed for fumaric acid production; fermentation process conditions including alternative feedstock, nutrients, and methods to control cell morphology, fermentation pH, and dissolved oxygen; and separation methods for fumaric acid recovery from the fermentation broth. We conclude that future research aiming at understanding the metabolic pathways and regulatory networks associated with fumaric acid biosynthesis, and searching for low-cost feedstock and more efficient fermentation and separation processes should pave the way leading to the development of an economical bioprocess for industrial production of fumaric acid from renewable biomass.