Bioconversion of Fumaric Acid to l-malic Acid by the Bacteria of the Genus Nocardia

The bacterial strains of the genus Nocardia were used for the bioconversion of fumaric acid to l-malic acid. The ability of the bacterial strain Nocardia sp. CCM 4837/A to produce l-malic acid from fumaric acid was investigated under various conditions. The optimal temperature for the bioconversion was approximately 37 °C, and the optimal pH was around 8.0. The addition of an inductor (fumarate salt) to the fermentation medium was necessary to enhance enzyme activity. The presence of detergent Triton X-100 (0.02–0.1 %) in the reaction mixture rapidly increased the enzyme activity of fumarase. The specific fumarase activity of intact cells Nocardia sp. CCM 4837/A increased from 2.8 to 75 U/mg after optimising the experimental conditions described here. Pretreatment of the Nocardia cells with malonate was not necessary because succinate was not detected as a by-product under our experimental conditions.