| Selenium is one of the necessary trace elements in human and animal bodies which have antioxidant, anti-aging, anti-cancer, tumor suppressor and other functions. Se-enriched probiotics has double effects:organic selenium and probiotic. It has high activity, low toxicity, wide safety range, high biological utilization rate and less pollution to environment, so it is widely used to study and production of se-enrich food. In china, about 2/3 area are selenium deficient. So it is very necessary to develop se-enriched food. Egg is one of the most common quality food in daily consumption. Due to rich in organic selenium, Se-enriched eggs become a safe and effective selenium supplementation way.In this study,3 strains of yeast and 15 strains of Lactobacillus were isolated from chicken intestine isolated.11 strains of Lactobacillus with the better acid producing ability were selected to 16SrDNA sequencing and phylogenetic analysis. The results showed that they belonged to Lactococcus lactis, Lactobacillus plantarum, Lactobacillus pentosus, Lactobacillus casei, Lactobacillus, Enterococcus faecium and fusion Weiss respectively.Selenium concentrations tolerance test of 9 trains of lactobacillus showed that Lactobacillus plantarum YQRS could grow in plate containing 100 ug/ml sodium selenite. And the color of the colonies was lighter than other strains under the condition of different selenium concentration. Further compared with above 9 strains se-enrich ability, strain YQRS had strongest se-enrich ability. By shake flask culture, its total selenium content reached 2303.22μg/L. Comparing of selenium resistance and selenium rich ability of 3 strains of yeast and two strains of Saccharomyces cerevisiae showed Saccharomyces cerevisiae FJYJM3 had the strongest se-enrich ability. By shake flask culture, the total selenium content was up to 5622.49μg/L.The optimal selenium addition concentrations and addition phases of strains YQRS and FJYJM3 were further studied, respectively. Results showed that when the sodium selenite concentration was 15 μg/ml, the total selenium content of strain YQRS was up to 2461.37μg/L, and when sodium selenite concentration was 20μg/ml, the total selenium content of strain FJYJM3 was up to 5155.491 μg/L. Adding selenium in 2h after inoculation, the total selenium content of strain YQRS was up to 2300.29 μg/L, and adding selenium in 4h after inoculation, the total selenium content of strain FJYJM3 was up to 5851.20μg/L.When strains YQRS and FJYJM3 were mixed cultured in the culture medium containing sodium selenite, the selenium content of 600μg/g biomass obtained. The alive probiotics, inactivated probiotics and sodium selenite were added to the diet according to different selenium content to measure its effect on the production performance and egg selenium content of laying hens, results showed that there was no difference in each group of egg laying rate, daily feed intake, average egg weight, feed/egg ratio (P≥0.05). Addition of 0.4mg/kg alive probiotics(as Se)in the diet, egg selenium content increased significantly by 63.27%, The average egg selenium content was 0.320 mg/kg. According to reports, egg selenium content more than 0.2mg/kg belongs to se-enrich egg, and it also accords with selenium limit 0.5mg/kg in the food hygiene standard (GB2762-2005).Finally, vacuum freeze drying technology was uesd to prepare of the compound preparation. Resault showed that when 10% of skim milk and 10% sucrose composed of composite cryoprotectant, The cell survival rate was the highest. Survival rate was still above 50% when save three months at room temperature. Using wheat bran as adsorbent for preparation of compound preparation showed that Survival rate was still above 50% when save three months at room temperature. This study could benifit for further foundation and production of probiotics preparation. |
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