Method for producing fumaric acid

摘要

Fumaric acid is produced by reacting maleic acid in an aqueous solution with a microorganism which has maleate isomerase activity or with a preparation from the microorganism having the maleate isomerase activity, and producing fumaric acid in a reaction solution by enzymatic isomerization of maleic acid carried out under the condition that the dissolved oxygen concentration in the reaction solution is substantially maintained at 4 ppm or less, for example, by sealing the reaction solution with one or more gases selected from N2, Ar, and He.