OPTIMIZATION OF CULTURAL CONDITIONS FOR LACTIC ACID PRODUCTION BY LACTOBACILLUS BULGARICUS ATTC 11842 GROWN ON WHEY

The effects on the lactic acid (LA) production by thermophile Lactobacillus bulgaricus ATTC 11842 on whey as a basal medium of seven factors namely, temperature °C, pH, Lactose g/l, Yeast extract g/l, corn steep liquor (CSL) g/l, K2HPO4 g/l, and salts g/l (MnSO4, MgSO4 and FeSO4) were investigated, through the statistical analysis of the results by Plackett and Burmann experimental design. pH was found to have the high significant effect on lactic acid production. By response surface methodology (RSM) design the optimal value of pH and concentrations in the medium of yeast extract, K2HPO4 and salts were then investigated, it should be 5.5 of pH, 2.73 g/l of K2HPO4, 1.59 g/l of yeast extract and 0.0326 g/l, 0.1304 g/l, 0.01304 g/l of MgSO4, MnSO4 and FeSO4 respectively. The results obtained with the optimal results were 20.9592 g/l. of lactic acid and the corresponding yields was 0.5665% (ratio between the amount of lactic acid produced and the initial concentration of lactose).