Study On The Technology Of High Cell Density Culture And Agent’s Producing Of Bifidobacterium Longum NCU712

Bifidobacterium is an important probiotics in human intestinal tract, it is important to prevent human disease and adjust the intestinal microecological balance. With the growth of the age, the number of bifidobacterium decreases gradually in the intestinal tract, in order to ensure the comprehensive probiotic effect in the live, he application of bifidobacterium in probiotics and food are becoming more and more widely. Bifidobacterium direct vat set research work mainly solved the difficulty of bifidobacterium in vitro culture, and can be used for industrialized production. This paper studies the bifidobacterium high density culture techniques and freeze-dried powder preparation technology.The article main research contents are as follows:1. B. longum NCU712 optimum fermentation culture medium formula research. On the basis of MRSC culture medium, using the single factor experiment determined the best composition of the glucose, yeast powder, K2PHO4 and fructooligosaccharide, according to the growth characteristic of B. longum NCU712. Medium components and mount were optimized by orthogonal design and uniform design. Through comparing the two kinds of optimization results, the study ultimately determined the best culture medium formula of B. longum NCU 712 were: glucose 0.5%, yeast powder 6.4%, K2HPO4 0.3%, MgSO4 0.02%, MnSO4 0.005%, 0.1% Tween-80, L-cysteine 0.05%, fructooligosaccharide 0.5%. Used the proliferation medium, incubated B. longum NCU712 for 20 h, viable count reached 1.39×109CFU/m L.2. B. longum NCU712 culture conditions and the fermentation strategy. Experiment condition on fermenter was determined by single factor experiment, inoculation quantity was 10%, culture temperature was 37 ℃, fermentation pH at 6.0. On the basis of the optimum fermentation conditions, according to the bifidobacterium growth curve, determined the optimal harvest time for 20 h. Using high performance liquid chromatography(HPLC) method, identified the metabolic product during the fermentation, mainly lactic acid and acetic acid. Therefore, organic acid components became the important reasons of acid stress to inhibit the growth of the B. longum NCU712. Using chemical neutralization in the high density cultivation, viable count reached 3.8×109CFU/m L.3. Highly active B. longum NCU712 direct vat set preparation technology research. On the basis of the high density cultivation, using the single factor experiment and orthogonal design experiments determined the freeze-dried protective agent formula were: monosodium glutamate 5%, glucose 5%, glycerol 3% and trehalose 5%. High density fermentation bacteria liquid was centrifugated 4500 rpm for 10 min, mixed with the protective agent, material thickness wtinin 6 mm, vacuum freeze-drying for 20 h. The bacteria agent viable count reached 3.3×1011CFU/mL, survival rate could reach 89.26%. B. longum NCU712 freeze-dried powder can store well at temperature below 4℃. After 60 days storage, the viable count could still reach 1.07×1011CFU/m L.