High density culture of lactobacillus casei by a Cross-Flow culture method based on kinetic properties of the microorganism

Abstract

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 = ν· X/ S f = 0.032 X, 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 0.30 1/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.