Study On Transgenic Saccharomyces Cerevisia And Lycopene Production

Carotenoids are yellow, orange,and red pigments which are widely distributed in nature. Lycopene is one of the major carotenoids and its functions include strong quenching of singlet oxygen,involvement in cancer prevention,and enhancement of immune responses.Saccharomyces cerevisiae has clear genetic background,The cell contains lycopene precursors and can be easily applied in the food industry, In the field of the lycopene transgenic research. Saccharomyces cerevisiae has many advantages and get more and more attentions and applications.At present,the carotenoids synzymes that used in transgenic saccharomycetic are all from bacterium and fungus.And the carotenoids synzymes in our study are from Gentiana lutea.They are phytoene carotenoids synzymes psy,phytoene carotenoids dehydrogenase pds and zds. Our Lab constructed three plasmids YCp22-Gal-psy YEplac195-pds,YEplac181-zds,and transformed in S. cerevisiae w303.The resultant yeast strains accumulated lycopene in the cells at 60μg/g (dry weight) of cells. This was considered to be a result of the carbon flow into ergosterol biosynthesis being partially redirected to the nonendogenous pathway for carotenoid production.In this study, the culture medium of Saccharomyces cerevisiae positive transformant is researched. By the study of rapidly available nitrogen resource, slowly available nitrogen resource,organic nitrogen resource,metal ion,validity and concentration of intermediate metabolites,8 factors, glucose, saccharose, peptone, yeast powder, sodium malate, sodium citrate, FeSO₄ and MgSO₄ brings positive effect to the production of lycopene. L27₃₈ orthogonal experiment of the 8 factors with 3 levels is launched, and the optimal medium for fermentation contains 2.4% glucose, 1.2% saccharose, 1.07% peptone,0.35% yeast powder,0.04% sodium malate,0.06% sodium citrate,0.01% FeSO₄ and 0.015% MgSO₄. It increases the production of lycopene by 60%. The purpose of screening is achieved primarily.