STUDY ON L-LACTIC ACID PRODUCTION BY BACTERIUM

Using facultative anaerobe-lactic acid bacteria to product L-lactic acid. When germ is cultured shakily for 18 h, it is transferred into fermentation medium. A suitable fermentation form-first cultured shakily for 24 h, then tuned to statically-was obtained through comparing several forms. The initial glucose concentration should be controlled in 120 g/L～140 g/L. Response surface methodology were applied to optimize 3 factors of medium,the optimized values of peptone, corn slurry and hydrolyzed liquor of bean dreg were 24.40 g/L, 10 g/L and 34.07 g/L, respectively. The fermentation form and optimized medium allowed lactic acid yield to 117.03 g/L in flask-shaking, sugar utilization to 97.53 %, pureness to 97.940 47 %, and utilization was increased 18.58 %.