The Optimal Conditions Study And Product Development In Mixed Culture For Bifidobacterium And Lactobacillus Acidophilus

Bifidobacterium and Lactobacillus acidophilus is found as an important class of probiotics which has the prebiotic function, such as, maintain the balance of intestinal microbial flora, enhance immunity, prevention and treatment of various gastro-intestinal diseases and so on. Therefore, probiotics and product development is increasingly becoming a hot research. However, because most of the probiotics is oxygen-intolerant, non-acid and easy deactivation, also it will emerge antagonistic phenomena between different strains, etc., which has limited their development and application and performance in some degree. In order to increase the number of viable probiotics and adaptive capacity, in this study, we take Bifidobacterium and Lactobacillus acidophilus as the two test bacteria and carry out studies as below:1. The study of optimal conditions in pure Culture for Bifidobacterium and Lactobacillus acidophilus(1) Optimization of carbon source: Made medium by adding 2% of inulin, sucrose, glucose, lactose and starch in the MRS medium which without carbon source. Then re-spectively inoculated 1% volume of two bacteria to a medium and cultured. The result shows that two strains can absorb the inulin, sucrose, lactose and glucose, but cannot absorb starch; can grow well in the carbon sourses with inulin, however, have lags in the carbon sourses which with sucrose or lactose.(2) Optimization of nitrogen source: Using four factors and three levels ortho-gonal experimental design, adding yeast ex-tract (A), peptone (B), soy peptone (C), and beef extract (D) with amount of 0.3%, 0.6% and 0.9% in the MRS medium which without nitrogen source. Then respectively inoculated 1% volume of two bacteria to a medium and cultured. Results, the four factors shown that A > C > B> D.(3) Optimization of Prebiotics: Made prebiotics medium by adding 1% stachyose, fructooligosaccharides, Isomaltooligosaccharide in the MRS medium, then respectively inoculated 1% volume of two bacteria to a medium and cultured. The result shows that these three kinds of oligosaccharides have more significant impact on growth of B.adolescentis, while there is no significant effect on growth of L. acidophilus, especially, fructooligosaccharides has more significant effect on growth of B.adolescentis than stachyose and Oligo-isomaltose.2. Optimization of growing conditions in mixed culture between B.adolescentis and L.acidophilusOptimization the mixed culture conditions of two bacteria by single-factor test and RSA response surface method, discussed the affects on the growth of mixed culture if by different concentrations ratio between two bacteria, pH value and different dosage of fructooligosaccharides for the mixed culture. The results shows that when the concentration ratio of the two bacteria was 1:1, pH value was 6.512 and the adding amount of fructooligosaccharides was 1.499%, the two bacteria has good microecological relationship in mixed culture system.3. Study on yield rate of viable B.adolescentis and L.acidophilusIn order to ascertain the best yield rate of viable two bacteria, we took centrifugal time and centrifugal rate as the factors, using four factors and three levels orthogonal experimental design. The results shows that we can get the best highest yield rate 83.1% under the conditions of 4℃, 30min, 6000r/min.4. New product development of B.adolescentis and L.acidophilusCompound two bacteria and Prebiotics, prepare synbiotics microcapsules, hard capsule and liquid preparation with different methods. Then took the capsules and preparation to do the following test, such as, acid resistant test, intestinal disintegration test and combined human gastric and intestinal juice effects test. The results shows that under the same condition, the survival rate of synbiotics microcapsules is higher than both hard capsule and the liquid formulations, and the survival rate can reach up to 70.8% after being artificial gastric juice for 2h, it could also get full degradation in artificial intestinal juice after 50 min, its dissolution rate is 96.7%, its survival rate was still can up to 66.8% after being combined artificial gastric and intestinal juice effect.