Construction And Improvement Of High Content Of β- Glucan Mutant In Saccharomyces Boulardii

S. Boulardii is a probiotics, which was isolated from lichees by the French researcher,Henri Boulard. At present, it is widely used in clinical medicine and livestock production in many countries around the world. S. Boulardii used as probiotics, was a range of application in Europe and America countries, preventing children and travelers from diarrhea. It used as a feed additive has been recognized by many countries in the world, including China, the EU. It will play a greater role in the development of medicine and animal husbandry, and also has broader prospects with the great attention of the people’s health and the environment and further research in livestock breeding. S. Boulardii is the most potential probiotics, β- glucan,the main component of the cell wall, plays a key role in the probiotics industry. Yeast β-glucan is a polysaccharide that enhanced activity of the immune system. S. Boulardii is undoubtedly one of the important sources of β- glucan in that the cell wall contains more than 50%β-glucan.However, the functional identity aims to the purified β-glucan mostly,β-glucan was the main component of cell wall of saccharomyces boulardi, there were no discoveries on the relationship between its content and probiotic function.This study built a high content of β-glucan mutant in S. boulardii through knock out the target gene by Cre-loxP gene knock out system.mutant is enriches natural resources ofβ-glucan, provide the materials for industry to extract the β-glucan.And research the changes of the phenotype about mutant, how the content of β-glucan has the effect on the probiotic function of saccharomyces boulard in vitro and animals. And research how the high content of β-glucan mutant effect on non-specific immunity, anti infection ability and performance for provide technical support and lay the foundation to further improve its probiotic characteristic.According to the objective and significance of this study,one gene called THP1 had been discovered which significantly affected the content of β-glucan in S. boulardii. And the mutant Sb-thp1,with high content of β-glucan was built by Cre-loxP gene knock out system.This system is a laboratory building suitable for S. boulardii. Research thephenotype of the mutant, we found that the growth of the mutant at a slower pace; on cell morphology, the mutant is bigger and rounder than the wide type; the cell wall was not sensitive to Congo Red、NaCl、SDS medium;the content of β-glucan cell wall was up-regulated, which enriches natural resources of β-glucan. What’s more, the result of the animal experiment show that the mutant were not improve the production performance anddid not increase the weight of immune organ of the experimental animals significanyly,but the mutant has the ability to resistant E.Coli infection,it can reduce the mortality.