HIGH-DENSITY CULTURE OF LACTOBACILLUS-CASEI BY A CROSS-FLOW CULTURE METHOD BASED ON KINETIC-PROPERTIES OF THE MICROORGANISM

The characteristics of Lactobacillus casei with respect to specific rates of cellular growth, glucose consumption and lactic acid production were elucidated through a study of cultivation with cross-flow filtration using a heatproof inorganic membrane module. These characteristics indicated that the feed rate of fresh medium per unit of culture volume D should be changed in proportion to the cellular growth as D = upsilon.X/S(f) - 0.032X, in order to obtain both a high cell growth rate and a high cell mass yield against glucose consumed. At a constant feed rate of 0.30I/h, 34 H and 214 l of fresh medium were required to obtain a cell concentration of 40 g/l(10(11)CFU/ml). On the other hand, by changing the feed rate based on the above equation, only 14 h and 162 l of fresh medium were needed to secure the same cell concentration. The volume of fresh medium required for the cultivation by changing the feed rate was 76% of that needed at a constant feed rate.