Indentification Of Three Lctobacillus Strains Applied In Feed And Study On Their Growth Property During Fermentation Process

In this paper,Lactobacillus SJ2-1、SJ2-2and SJ2-3applied in feed were identified by16S rDNA sequencing and their biological characteristics and growth property during fermentation process were studied.The bacterial biomass was greatly improved, thus the production costs decreased.Lactobacillus SJ2-1, Lactobacillus SJ2-2, Lactobacillus SJ2-3were identified as Lactobacillus satsumensis, Lactobacillus casei and Lactobacillus sp.71. by16S rDNA sequenceing, respectively. Phylogenetic tree was constructed by16S rDNA sequencing and blast from three Lactobacillus strains.Lactobacillus SJ2-1and SJ2-2were studied on their biological characteristics.The results showed that Lactobacillus SJ2-1can tolerate a5%NaCl and2.0g/L bile salt and can be grown in pH3.5medium, Lactobacillus SJ2-2can tolerate a7%NaCl,2.5g/L bile salt and can be grown in pH2.5medium, two strains both can be grown at45℃with good heat resistance.The optimal medium for biomass growth by using RSM was obtained as follows: industrial glucose36g/L,corn steep liquor50.4ml/L,NaAc10.42g/L, MgSO4·7H2O0.2g/L, MnSO4·H2O0.01g/L, FeSO4·7H2O0.01g/L, NaCl0.01g/L,1ml/L Tween-80. Under the optimal condition, the biomass OD600of Lactobacillus casei SJ2-2reached3.686, increased by81.8%, compared to the culture with original medium.Three Lactobacillus strains were also studied on growth property in a5L fermentor.The results indicated that the maximum biomass of Lactobacillus casei SJ2-2increased by84.5%in the optimized medium than that in GYP medium, proving successful optimization by response surface methodology. Finally, the growth dynamics models for batch culture of three Lactobacillus strains were also studied and the related parameters were analyzed.