Identification of a Strain of Leuconostoc lactis and Optimization of Its Bacteriostatic Medium Formula

In order to utilize the resource of Lactobacillus and its metabolites,a Lactobacillus from self-made kumiss in inner Mongolia was identified by the 16S rRNA sequence analysis. The bacteria was identified as Leuconostoc lactis and this stain was studied as the research object. The diameter of the bacteriostatic circle was taken as the index,and single factor experiment and the response surface method were used to optimize the medium composition. Sucrose was identified as the optimal carbon and peptone was identified as the optimal nitrogen. The optimal formula of the culture medium were as follows(g/L):sucrose 24.84 g/L,peptone 12.72 g/L,CH₃COONa 3.95 g/L,K₂HPO₄ 2 g/L,beef powder 5 g/L,Tween 80 1 ml/L,C₆H₁₇N₃O₇ 2 g/L,MgSO₄ 0.2 g/L,MnSO₄ 0.05 g/L.Under the optimal conditions,the diameter of inhibition zone had reached 23.40±1.28 mm,and it had increased 2.1 times than before,which was consistent with the value predicted by the mathematical model.