Studies On Screening Highly Produced Proteinum Yeast By Fermentation Of Molasses And Optimizing Conditions Of Fermentation

In this study, a Saccharomyces cerevisiae strain 10Y preservationed in our laboratory was treated with ultraviolet radiation and using beet molasses as fermentation substrate to get a positive mutation yeast strain 12B-8 that contained more biomass and protein. The biomass was up to 11.26g/L, protein content of the yeast cell was up to 34.15% and total protein yield amounted to 3.85g/L, which discern was 32.6%,3.3%,37.0% higher than that before mutation. Strain 12B-8 was transferred 10 times, but its biomass and protein content in cells were changed not greatly. The result showed that this strain had stable genetic characteristics and could be used for industrial production of single cell protein after improvement.To mutation yeast strain 12B-8 being screeninged, single cell protein was produced by using beet molasses and the optimized conditions were studied. By the single factor and orthogonal design experiments L16(45).The optimal combinations were as follow:The initial pH of culture medium was 5.0,the zymotic fluid cubage was 75mL/250 mL,the rotational speed was 180 r/min,and then cultured on the shaking table at 28℃for about 84 h.Under the optimized conditions,the yeast total protein yield was 4.35 g/L, which was 41.69% higher than that before optimization.The mutation yeast strain 12B-8 being screeninged and the initial yeast strain 10Y were used to breed mice.The resut of the studying discovered that The mutation strain 12B-8 and the initial strain 10Y cound raise the production trait of mice including the body weight and the forage transformation efficiency and enhance the immunity function of mice. The mutation yeast strain 12B-8 was better than the initial yeast strain 10Y in raising the production trait of mice.