Study on screening the high L-lactic acid production strain of Lactobacillus casei and its fermentation conditions

Using Lactobacillus casei G-02 as a starting strain for induction by diethylsulfate(DES),N-methyl-N′-nitro-soguanidine(NTG)treatment,and selecting using high temperature and high sugar concentration culture conditions,a L-lactic acid hyper-producer G-04 was obtained.The effect of dissolved oxygen,neutralizer,and feeding on L-lactic acid production in 7L bioreactor were also discussed.Experimental results showed that the strain can accumulate L-lactic acid 188g/L,sugar conversion efficiency more than 90% and the fermentation period less than 44h under the optimized fermentation conditions.