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

The mutant strains of Candida rugosa were developed for enhanced enantiosel ective production of D(-)-beta-hydroxyisobutyric acid (D-HIBA) from isobuty ric acid (IBA). Three mutant strains, C. rugosa MME 1027, MME 1259 and MME 1559, which can not assimilate propionic acid, were screened. The molar con version yield and D-HIBA productivity were compared in fed-batch cultivatio ns of the mutant strains. The maximum D-HIBA concentration of 150 g l(-1) w ith the highest molar conversion yield of 81.8% was achieved with the strai n MME 1259, while the highest productivity of 1.1 g l(-1) h(-1) was obtaine d with the strain MME 1027. (C) 1999 Elsevier Science B.V. All rights reser ved.