EFFICIENCY OF LACTIC-ACID PRODUCTION BY LACTOBACILLUS-HELVETICUS IN AMEMBRANE CELL RECYCLE REACTOR

An economic evaluation is presented of lactic acid production in a mem brane cell recycle reactor. From this evaluation it is concluded that the economic feasibility of the process is primarily limited by produc tion capacity and product concentration and to a lesser extent by prod uctivity. In membrane cell recycle reactor experiments and batch culti vation experiments with Lactobacillus helveticus, it is shown that the economic feasibility of the process using this organism is limited by organic acid inhibition resulting in energy uncoupling of anabolism a nd catabolism. Due to this inhibition, the maximum lactic acid concent ration that can be obtained in the membrane reactor process is 50 g l( -1). Furthermore it is shown that not only the fermentative conversion of lactose into lactic acid but also the hydrolysis of lactose into g lucose and galactose is an important process. The beta-galactosidase a ctivity needed for the hydrolysis is generated during the exponential growth phase of Lb. helveticus.