Continuous production of lactic acid in a cell recycle reactor

The production of lactic acid from glucose has been demonstrated using a CSTR (continuous stirred-tank reactor) with cell recycle. Studies were conducted with Lactobacillus delbrueckii at a fermentation temperature of 42 degree C and a pH of 6.25. A cell density of 140 g dry weight/L and a volumetric productivity of 150 g/L multiplied by h, with complete glucose consumption, were obtained. It was not possible to obtain a lactic acid concentration above 60 g/L because of product inhibition. The specific glucose-consumption for cell maintenance was 0.33 g glucose/g cells multiplied by h.