pH-dependent continuous lactic acid fermentation by Lactococcus lactis IO-1 using hydrolyzed sago starch.

High dilution rate and high cell density continuous lactic acid production by Lactococcus lactis IO-1 in hydrolyzed sage starch medium was investigate d using a pH-dependent feed system coupled with cross flow filtration and t urbidity control. Lactate production and productivity were dependent on cel l density, dilution rate and feed glucose concentration. At a cell concentr ation of 15 g/l and a feed glucose concentration of 50 g/l, volumetric lact ate productivities of 14.9, 23.5 and 33.0 g.l(-1).h(-1) were obtained at di lution rates of 0.35, 0.5 and 1.1 h(-1) respectively. The respective residu al glucose concentrations in the permeate were 0.8, 1.0 and 3.7 g/l. On inc reasing the feed glucose concentration to 64 g/l, volumetric lactate produc tivities of 12.4 and 32.3 g.l(-1).h(-1) at dilution rates of 0.21 and 0.70 h(-1) were obtained while the respective residual glucose concentrations in permeate were 2.7 and 12.2 g/l.