Construction Of Yeast Engineered Strain For Ly-Copenen Production And Its Fermrntation Process Optimization

Lycopene, which belongs to carotenoids, has lots of applications, including antioxi-dant activity, regulation of cell growth and metabolism, regulation of cholesterol metabo-lism, prevention and suppression of tumor and the health care fruction. In order to biosyn-thesis lycopene in yeast, the CrtB and CrtI genes were firstly integrated at the δ DNA locus of Saccharomyces cerevisiae BY4742, resulting in strain ZD-Ly-100. Several key genes in the terpenoid synthetic pathway, including HMG1, IDI, ERG20, and SaGGPS, were further regulated to improve lycopene production, found that the two key enzyme HMGR and GGPS controle the biosynthesis of two terpenes.Construction and optimization of the heterologous pathway involved in assembly of multiple genes. In this work, through DNA assembly technique, the tHMGl gene that con-trolled synthesis of the common terpeniod precursor and the ERG20-BTS1and SaGGPS genes that controlled production of diterpenoids were integrated together into the rDNA sites of strain ZD-Ly-000, resulting in strain ZD-Ly-201. The lycopene yield increased77.0times to13.23mg/L compared to ZD-Ly-000.It was found that high cell mass could be obtained when using exponential feeding method while lycopene yield was kept at a high level in the further fermentation process optimization, OD600can be as high as500; during the high density fermentation, when the OD600was about200, limit the concentration of phosphate can control the rapid growth of cell, so as to promote the accumulation of target products; during the high density fermen-tation, in the middle log phase, the organic solvent is added to the fermentation tank through the line extraction, establish a two-phase fermentation system, can reduce the bur-den of cells, so as to promote the accumulation of target products(Increased about2Times). After a series of optimization can improve the lycopene and ginsenoside production in a greater degree. Using this fermentation strategy,135.21mg/L lycopene was produced which was10.2-fold higher than that using shake flask condition, and ginsenoside yield was increased from0.31g/Lto1.59g/L. This study provides the basisis for the production of lycopene、ginsenoside and other natural products by fermentation.