| Probiotics mainly include lactic acid bacteria, bacillus, yeasts and so on. It has many benefits:nutrition and promoting digestion, regulation of intestinal microflora balance, stimulating the animal’s body to enhance the immunity. As a new feed additive, probiotics are non-toxic, no residue and effective. It can effectively alleviate the current issues in food safety and the environment due to the abuse of antibiotics.In this thesis,4 strains probiotics named as LZ13, ET11, PJ03 and BY06 were isolated from animal intestinal. Physiological, biochemical and 16S rRNA phylogenetic analysis showed that the 4 strains probiotics were Lactobacillus salivarius, Enterococcus faecium, Pediococcus acidilactici and Bacillus subtilis, respectively, and they all had significant probiotic characteristics like bacteriostasis and tolerance.Strains of ET11 and BY06 were selected to investigate for the optimization of medium components, culture conditions and the results was verified on the other 2 strains of lactic acid bacteria. Results showed that the biomass were improved significantly.The factors of initial pHã€Âliquid volume and nitrogen source which had significant effects on the viable counts of ET11 strain and BY06 strain, were selected for Box-Behnken Design to optimize the mixed culture of Enterococcus faecium ET11 strain and Bacillus subtilis BY06 strain. The results showed that the viable counts of the 2 strains could reach to 6.99x1010CFU/mL, which was five times than before optimization.Cell collection and freeze-drying were important parts in the producting of microorganism preparation. Results showed that the optimum centrifugation speed and time for ET11 were 6000 rpm,30 min, and for BY06 were 6000 rpm,15 min. Both the yield of the 2 strains were above 88%. Optimization of freeze-drying thickness and protective agent showed that the lyophilization survival rate of ET11 and BY06 were more than 65%. The storage stability of freeze-drying and direct absorption were detected, the survival rate of direct adsorption was slightly lower than that of freeze-drying after 150 d, but maintained at about 63%.At the end of this thesis, the application of probiotics and Chinese herbal medicine and maggot powder in broiler production were studied. The experiment was divided into 5 dietary treatments (probiotics 1, probiotics 2, probiotics 2+Chinese herbal medicine+maggot powder, Chinese herbal medicine+maggot powder and control group), the results showed the 4 experimental groups improved the growth performance, intestinal physiology and the antioxidant and immune ability in different degree, so it has a certain application prospect for industrial application. |
