The Optimization Of Defined Medium And Process Study For Lactic Acid Fermentation By Lactobacillus Paracasei

A defined medium was optimized for lactic acid production by Lactobacillus paracasei in this study. Plackett-Burman design was used to identify three main factors, amino acids, potassium dihydrogen phosphate and calcium carbonate, from total eight factors on lactic acid production. The experiment of steepest ascent path was adopted to approach the optimal region of three main effectors. Finally, the optimal concentration of each factors was determined by of Box-Behnken design. In a5-L fermentor, the metabolic characteristics of lactic acid fermentation processes under different aerobic conditions indicated that microaerobic cultivation promoted the consumption rate of glucose and lactic acid production of lactic acid in both of defined medium and complex medium. The yield of lactic acid on glucose in microaerobic cultivation was lower than that in the nonaerobic cultivation. The utilization of amino acid during fermentation demonstrated that Lactobacillus paracasei can metabolize most of the twenty kinds of amino acids, but tryptophane, histidine and methionine were consumed slowly. The cell growth and lactic acid formation dynamic model were constructed under different culture conditions. The correlation coefficient maintained at0.99, indicating that a good fitting was obtained between the calculated values and the experiment data.