Optimized fed-batch fermentation of L-beta-hydroxy isobutyric acid by Yarrowia lipolytica

Yarrowia lipolytica KCCM50506, which transforms isobutyric acid to L-beta-h ydroxy isobutyric acid (L-beta-HIBA), was screened. Chemostat cultures were carried out in jar fermenters at dilution rates of 0.02 h(-1) to 0.12 h(-1 ) L-beta-HIBA fermentation-regulating factors were determined to be specifi c growth rate, and concentrations of glucose and isobutyric acid in ferment er from analysis of steady-state data. The specific productivity of L-beta- HIBA increased as the specific growth rate increased, apparently as a growt h-associated type of product formation. A fed-batch culture was carried out under optimum conditions where the concentrations of glucose and isobutyri c acid in the fermenter were maintained at 23 g l(-1) and 9 g l(-1), respec tively. The concentrations of cells and L-beta-HIBA obtained at the end of fermentation were 20 g l(-1) and 49 g l(-1), respectively, corresponding to 2.0 and 2.7 times more than concentrations in batch culture.