High Density Culture And Anti-allergic Function Of Lactobacillus Kefiranofaciens ZW3

Lactobacillus kefiranofaciens ZW3 has excellent biological characteristics and probiotic function.In this study,Lactobacillus kefiranofaciens ZW3 was cultured in high density to prepare direct-cast starter and was used to investigate the anti-allergic immune mechanism.The safety-related genes of Lactobacillus kefiranofaciens ZW3 were analyzed based on RAST database and VFDB database.Firstly,the proliferation medium and culture conditions of Lactobacillus kefiranofaciens ZW3 were optimized.The optimum medium components were:glucose 4%(m/v),peptone 2%(m/v),yeast extract 0.5%(m/v),MgSO4·7H2O 0.02%(m/v),MnSO4·4H2O 0.02%(m/v),K2HPO4 0.2%(m/v),triamine citrate 0.2%(m/v),tween-800.1%(v/v),sodium acetate anhydrous 0.5%(m/v).The factors affecting the high-density fermentation were optimized in 7L semi-automatic fermentor.The optimum high-density fermentation was obtained as follows:neutralizer 20%sodium hydroxide,pH4.9,stirring speed 100 r/min,temperature 30?.Under these conditions,after 48 hours of high-density fermentation,the number of viable count in the broth and powder could reach 1.13 ×108 cfu/mL and 2.2 × 109 cfu/g,respectively.Then,the anti-allergic immune mechanism was explored by Lactobacillus kefiranofaciens ZW3 starter preliminarily.The allergy score,serum OVA-sUgE,body mass,thymus and spleen index were detected.The levels of IL-2,IFN-?,IL-4,IL-5,IL-10 and IL-13 were detected by RT-qPCR.The changes of fecal flora were detected by bacterial culture method.The body weight and thymus index of mice administrated with Lactobacillus kefiranofaciens ZW3 returned to normal levels;allergy score,serum OVA-sIgE,intestinal Escherichia coli,IL-4,IL-5,IL-10 expression decreased;IFN-?,IL-2 expression and intestinal Lactobacillus increased,suggesting that Lactobacillus kefiranofaciens ZW3 ameliorated allergic symptoms induced by OVA in food allergic mice.Finally,the safety related genes of Lactobacillus kefiranofaciens ZW3 were analyzed.The adhesion related genes,bile hydrolysis related genes,ion transport related genes,and antibiotic resistance related genes were screened by RAST database.There are cpsB,cpsF,clpC,clpE and clpP were screened by VFDB database.It is considered that Lactobacillus kefiranofaciens ZW3 does not have virulence genes based on gene level analysis.