Enhanced production of D-β-hydroxyisobutyric acid through strain improvement

Abstract

The mutant strains of Candida rugosa were developed for enhanced enantioselective production of D(-)-β-hydroxyisobutyric acid (D-HIBA) from isobutyric acid (IBA). Three mutant strains, C. rugosa MME 1027, MME 1259 and MME 1559, which can not assimilate propionic acid, were screened. The molar conversion yield and D-HIBA productivity were compared in fed-batch cultivations of the mutant strains. The maximum D-HIBA concentration of 150 g l-1 with the highest molar conversion yield of 81.8% was achieved with the strain MME 1259, while the highest productivity of 1.1 g l-1 h-1 was obtained with the strain MME 1027.