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Astaxanthin is a carotenoid, has strong ability to quench free radicals and also has a strong coloring ability, so in medicine, cosmetics, food and feed industry has a wide range of applications. Phaffia yeast fermentation of astaxanthin, in order to cultivate a short time, without light and can get the advantages of high-density culture attention.Metabolic engineering methods for the transformation of a common means of knockout strains of certain key genes bypass to reduce the diversion of carbon metabolism or overexpression of certain key genes. This wild-type Phaffia yeast As2.1557 as the original strain, should determine the key enzyme in the upstream gene encoded on the start, through crtE gene amplification, increased astaxanthin precursors, and then examine its Phaffia yeast growth and astaxanthin production impact.crtE gene coding based Mang Mang ox ox base pyrophosphate synthase (GGPP), GGPP is a variety of primary and secondary metabolites of a common precursor for many diterpenes, carotenoids, chlorophyll, and vitamin E quinone side chain, etc. to provide building skeleton. Therefore, GGPP synthase could play a role in regulating carbon flow in order to become primary and secondary metabolic pathways in one of the key enzymes.In this study, the method by homologous recombination was constructed of two transformation vectors, pSX-pc and pSX-gc,. The two carriers are rDNA as homologous arms, respectively crtE own promoter gene, and the replacement of a strong promoter of crtE gpd gene was transformed into the yeast Phaffia, and integrated into its genome to G418 as anti- sexual selection marker, the ultimate success of selected gene amplification crtE strains.By measuring its growth curve, carotenoids and astaxanthin content, found that compared with the wild strain, the overexpression of GGPP synthase for the conversion of strain after the growth rate declined slightly; to replace the gpd gene as the promoter crtE amplified strain vector transformation, due to increased gene expression, thereby enhancing astaxanthin content, up to a 464.37μg/gDCW; to not replace the promoter crtE gene amplification vector transformation strain, as integrated copies few more, GGPP synthase and a corresponding increase in the expression, enhance the astaxanthin content of the most significant to the 503.22μg/gDCW.
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