Production of Fumaric Acid by Rhizopus arrhizus

The formation of appreciable quanitities of fumaric acid by fermentation is largely confined to organisms of the order Mucorales and in particular to the genus Rhizopus.Production of fumaric acid by these fungi has been reviewed by Foster (1949, 1954), whose papers may be consulted for prior references.Fumaric acid production is not strictly a one-product fermentation.Under limited conditions selected strains of Rhizopus produce primarily fumaric acid, but usually ethanol is present together with a substantial proportion of acids other than fumaric.In general, weight yields of fumaric acid have been reported as high as 40 to 50 per cent of the sugar fermented, glucose being the most commonly employed carbohydrate.Optimal conditions for the production of fumaric acid have not previously been clearly defined for either surface or submerged fer- mentations.According to published data, the level of various components of the fermentation medium such as carbohydrate, potassium, iron, magnesium, zinc, and copper can greatly influence the yield.The purpose of this paper is to describe the optimal conditions for the production of fumaric acid in shaken flask culture. MATERIALS AND METHODSThe compositions of the media employed in this work are summarized in table 1.The two media (C and D) are optimum for the laboratory-scale production of fumaric acid by the two strains of molds used.The organisms were cultured on slants of medium A for 5 to 7 days at 33 C to obtain a massive crop of spores.The spores were washed from slants of medium 1 Presented at the 58th General Meeting of the Society of American Bacteriologists, Chicago, Illinois, April 27 to May 1, 1958.