Fig. 1

a Biosynthesis pathway of astaxanthin in yeast. The pathway from β-carotene to astaxanthin was boxed in the red line and engineered in this study. b Astaxanthin producing strain. The modular gene cassettes of crtE, crtI, crtYB were inserted into the CAN site of BY4741, while the Aa. crtZ and B. DC263 crtW were integrated into the retrotransposon of Ty1. c Profile of astaxanthin yield (green), astaxanthin titer (pink), and cell density (blue) during fermentation of astaxanthin producing strain yQDD001. d Sketch map of crtZ and crtW expression cassettes. Expression modules of all crtZs were assembled with FBA1 promoter and ADH1 terminator. And the expression modules of all crtWs were assembled with TDH3 promoter and TDH2 terminator