Screening Of Biomass And Trehalose Accumulation Saccharomyces Boulardii Strains

Saccharomyces boulardii isolated from Indonesian lychee was a enshrine yeast, had the heat resistance and can grow in 37℃, which belonged to a subspecies of S.cerevisiae. It had been widely applied to humans fighting diarrhea drug, to all sorts of intestinal inflammation having good curative effect, the effect of infantile and travelers diarrhea particularly remarkable. Its micro-ecological pharmaceutics used in animals husbandry can not only effectively reduce the pathogen and its toxins concentration, but also were very beneficial to the healthy and rapid growth of animals, therefore it would have wide application prospects in animal husbandry. In our study of S.boulardii, its resistance capability was not strong. In the process of living strains preparations, S.boulardii had high mortality rate, and the results showed that trehalose had magical protection for this.In this study, through the natural regeneration and multiple ultraviolet mutagenesis, we obtained high biomass of S.boulardii and high-yield trehalose strains.Using the strains selected by mutagenesis as original strains, the culture medium composition and culture conditions of Saccharomyces boulardii were optimized. After the optimization,the culture medium composition and culture conditions obtained as follows: the best carbon source conditions was glucose, and its optimal concentration was 10%; the best nitrogen source was citric acid three ammonium, and its optimal concentration was 0.7%; the corn pulp was 1.5%; potassium dihydrogen phosphate was 0.2%. The optimal fermentation temperature was 30℃; the optimal pH was 5.5; fermentation strains were vaccinated after culturing 16h, inoculation amount was 10%; Using wave bottle fermentation, wave bed speed was 200r/min,fluid amount loaded in conical flask was 100mL/500mL, optimal cultivation time was 18h.Finally, we have verified that the strains of mutants were better growth state in optimal fermentation by comparative experiments. Compared with the original strains in the ordinary fermentation medium, the mutant strains in the fermentation medium after the optimization had better growth. The biomass is up to 4.2g/100mL and the trehalose content is up to 56mg/mL , increased by 35.5% and 30.2% respectively. This proved that the study based on screening mutagenesis and medium optimization has been achieved the below research purpose, to improve S.boulardii biomass and trehalose production.