Malease-catalyzed production of D-ma late by coupling reaction and separation

Maleate hydratase from Pimelobacter simplex DM18 was used to effectively produce D-malate from maleate. To avoid the inhibition of the hydratase from product and substrate of high concentrations, calcium-ligand complex was used in this reaction system, because of the low solubility of Ca-maleate and Ca-malate. Ca-maleate as a substrate was conversed into Ca-malate by maleate hydratase through coupling reaction and separation, and high biocatalyst velocity was maintained during the process by regulating the ratio of the complex maleate to free maleate. After 36 h of reaction, 385 g/L of Ca-D-malate was produced. This is equivalent to 300 g/L of D-malic acid, with a 99% mol yield, and 97.03% in optical purity.