Application of dialysis culture to L-lysine fermentation

In Brevibacterium flavum QL-5, aspartate kinase was sensitive to feedback inhibition in the simultaneous presence of L-lysine and L-threonine. The simultaneous addition of these two amino acids (1mM each) produced about 60% inhibition. The inhibition was reduced to about 40% by dialysis. Similarly in L-lysine production by resting cells, the simultaneous addition of these two amino acids (1mM each) produced 35% inhibition, and dialysis reduced the inhibition to 12%. Dialysis culture was used in L-lysine production by Brevibacterium flavum QL-5 with 10%_??_20% glucose concentration. In dialysis cultures, the lag phase was shortened and cell mass increased compared with non-dialysis cultures. Moreover in dialysis cultures, L-lysine was produced early, and the maximum productivity of L-lysine (1.50g/l/hr) was obtained in 6 through 10 hr cultivation. The maximum productivity in dialysis cultures was 2_??_6 times higher than in non-dialysis cultures at the same culture period. The amounts of L-lysine produced in dialysis culture at 10%, 15% and 20% glucose concentrations increased 105%, 120% and 126%, respectively, as compared with non-dialysis culture at the same glucose concentration. In all dialysis cultures, the yield of L-lysine per glucose consumed was about 30%.