Optimization Of Culture Conditions And Drying Technology Of Probiotic Bacteria On Sheep

The objective of this paper was to optimize the culture medium formula and drying condition of the probiotic yeast and Bacillus subtilis which were isolated in our lab.The experimental results were as follows:In the first experiment,we optimized the culture medium for the probiotic yeast strain.We selected the suitable ingredient for the medium based on the single factor design experiment.The optimal carbon source was fructose,the best nitrogen sources were yeast powder and beef paste,and addition of VB1 could improve the growth of the yeast.We optimized the yeast medium formula based on Box-Behnken response surface design experiment.The formula was as follows: fructose 36.60 g/L,VB1 0.17 g/L,yeast powder 12.46 g/L,and beef paste 18.11 g/L.The average growth concentration of the yeast strain after optimization was OD600 =6.46,which was 2.4 times higher than that of OD600=2.68 before optimization.In experiment 2,we optimized the culture medium for the Bacillus subtitles strain.The suitable ingredient for the medium were selected based on the single factor design experiment.The optimal carbon source was glucose,nitrogen source were yeast powder,lepton and beef extract,and appropriate amount of VB6 and Na Cl were added in the medium.We optimized the Bacillus subtitles medium formula based on Box-Behnken response surface design experiment.The formula was as follows: glucose 13.24 g/L,VB6 0.17 g/L,yeast powder 18.28 g/L,beef paste 13.47 g/L,and lepton 12.92 g/L.The average growth concentration of the Bacillus subtitles strain after optimization was OD600 =8.48,which was 2.9 times higher than that of OD600=2.87 before optimization.In experiment 3,the bacterial protectant,carrier,and vacuum drying conditions were optimized base on single factor and orthogonal designed experiment.The optimal drying condition was as follows: the best microbial protectant for drying process was seaweed 120 g/L,sorbitol 80 g/L,lactose 60 g/L,sucrose 120 g/L.The best ratio of bacteria to protectant was 1:2.The corn meal was used as the microbial carrier.Drying microbial for 6h under pressure 0.08 Mpa,the yeast powder can be stored for 1 month at 4 ?after vacuum packing.