Comparison of fumaric acid production by Rhizopus oryzae using different neutralizing agents

Abstract.

Fumaric acid fermentation in a 10-L bubble column fermenter using different neutralizing agents [CaCO₃, Ca(OH)₂, NaHCO₃] by Rhizopus oryzae ATCC 20344 was examined. It was found that in the fermentation using CaCO₃ as the neutralizing agent the highest fumaric acid weight yield and volumetric productivity were obtained, 53.4% and 1.03 g/L×h^–1 respectively. In the NaHCO₃ case, the fumaric acid weight yield and volumetric productivity were 33.7% and 0.69 g/L×h^–1, respectively, much lower than the CaCO₃ case. However, the NaHCO₃ alternative has advantages of cell reuse and simple downstream processing because of the high solubility of sodium fumarate. These advantages may offset the disadvantages of using NaHCO₃ as the neutralizing agent, and the overall fumaric acid weight yield and volumetric productivity will increase.