A Primary Study Of The Breeding And Culture Condition Of A Selenium-Enriched Yeast Strain With High-Biomass

The trace element-se is one of necessary elements, which can maintain body's natural life activities. Lack of se would induce a lot of diseases. The content of se in natural food is always very low, and inorganic se can't be used in food because of its higher toxicity, so it weighs heavily that synthesize kinds of Se-enriched food by microorganism. Started with a yeast strain supported by our laboratory in this paper, the breeding and condition optimization has been studied, and this has built a favorable base for further use in industrialized production.Domesticating this train by gradual screening, we have gained a strain J2 with higher biomass and resistance to se, then by ultraviolet Mutagenesis to J2 ,we have screened and gained another strain J51.After fermentation experiments ,we have ascertained that its biomass is up to 8.94 g/L, and its se content of the cells is up to 1524.31μg/g, rising 1.142 times and 1.265 times as before the Mutagenesis respectively.We have found JS1's optimum fermentation conditions by condition optimization and a L₂7(3¹3) orthogonal test, which is as followed: glucose 5%,beef peptone 1.0%,yeast extract 1.0%, KH₂PO₄0.3%, MgSO₄0.15%.the initial pH of culture medium is 4.0 ,and the initial se concentration is 7.5μg/ml, then add to 25μg/ml when the fermentation of yeast reach logarithmic phase .The inoculatingcontent is about 8% ,and then culture on the shake bed with 200rpm at 31℃ for about 60h.Under the optimized conditions, the biomass(dry weight) reached 10.024g/L with the se content of the cells being up to 2215.74μg/g, and the total se content reached 22210.578μg/L, in which the organic se is up to 91.64%, rising 1.280 times and 2.355 times as before the Mutagenesis respectively. Consulting the paper published openly, we find that the maximal value is reported by Fan Xiuying etc. of Institute of Microbiology of CAS in Beijing .From the paper we know that under the optimized conditions, the biomass(dry weight) reached 8.2g/L with the se content of the cells being up to 2050μg/g, and the total se content reached 16810μg/L, in which the organic se is up to 91%-The result of the paper is higher than the maximal value and lies the advantage level of our country presently.