The Isolation And Identification Of Feed Yeast And The Research And Manufacture Of Compound Probiotics

Today in the process of animal husbandry production, the growth-promoting and disease prevention of animal are still dependent on antibiotics, but the dnedative effects of antibiotics are becoming increasingly prominent. So, to look for a kind of new and safe additive has become to be a reslistic. Animal probiotics are live microorganisms that can improve the balance of intestinal flora, and the important approach to produce safe, pollution-free and nonrudimentation livestock product.In my experiment,8 yeasts were isolated from probiotics product and pig manure, and identified these yeasts using the method of 26S rDNA D1/D2 gene sequence analysis. There are 6 feed yeasts and 2 Trichosporon domesticum strains. Research the biological characteristics of Saccharomyces cerevisiae. I studied the liquid permentation of Yeast and Bacillus subtilis, and three strains multi-strains co-fermentation. Freeze-drying, spray drying and drying were researched, and discuss the advantages and disadvantages of three processes.Specific results are as follows:(1)50L fermentor fermentation conditions are as follows:inoculation amount 5%, the growth temperature 30℃, aeration rate 1.3 Nm3/h, stirringspreed 180rpm, defoamer3% and 1% soybean oil. Under these conditions, the biomass of Saccharomyces cerevisiae is 1.42×1011cfu/ml.(2)Through single factor erperiment and orthogonal test method, optimal fermentation medium and culture condition were established.Fermentation medium are as follows: Sucrose 2%,Bean pulp2%, NaCl 0.1%, MgSO4 0.02%, MnSO4 0.005%, KH2PO4\K2HPO40.3%:0.1%,0.02%CaCl2; fermentor culture condition are as follows: medium volume 60%, inoculation amount 1%, optimal initial pH 7.0, the growth temperature 30℃, stirr 180rpm,aeration in 1:0.3-0.5. The highest biomass obtained in the experiments was 5.3×1012cfu/mL.(3)According to the cooperation relations of various strains, a liquid fermentation process of multi-strains co-fermentation was preliminarily established. The multi-strains mix fermentation condition:inoculation amount was 5%, ferments temperature was 35×, stir was 180rpm, the inoculation order was Yeast and Lactic acid bacteria firstly, then the Bacillus subtilis.(4) We investigated the protective agents that add in the processes of bacterial powder using the vacuum freeze-drying technology. The Yeast cryoprotectant were 10% skimmed milk and 5% maltodextrin, biomass was 9.31×1010 cfu/ml, the survival rate was 65.6%; The cryoprotectant of Lactic acid bacteria and Bacillus subtilis were 10% skimmed milk and 10% sucrose, the biomass were 1.44×1011 cfu/mlå'Œ1.52×1011 cfu/ml, the survival rate were 68.6% and 82.6%.(5)Inlet air temperature was 160℃,the outlet temperature was 77℃,5% skimmed milk as protective agent, under these conditions, the bacterial powder was exquisite and not sticky. The result of drying agents of these strains are as follows:the biomass of Saccharomyces cerevisiae was 6.25×1010cfu/ml, the survival rate was 44.0%; the biomass of Lactic acid bacteria was 1.16×101'cfu/ml, the survival rate was 55.2%; the biomass of Bacillus subtilis was 1.15×1011cfu/ml, the survival rate was 62.5%.