S. cerevisiae YSG50 (MATα, ade2-1, ade3Δ22, ura3-1, his3-11,15, trp1-1, leu2-3,112 and can1-100) was used as the host for DNA assembly and integration. The pRS426 and pRS416 plasmid (New England Biolabs, Beverly, MA) were modified by incorporating the hisG and partial δ sequence (δ2) that flank the multiple cloning site and serve as the vectors for assembly of various pathways (Supplementary Figure 1). The resulting pRS426m and pRS416m were linearized by BamHI. The δ1-hisG-ura3-hisG fragment was cut from pdδUB (30 (link)) with BamHI and XhoI. Plasmid containing the cDNA (psXKS1) encoding d-xylulokinase (XKS) was a gift from T.W. Jeffries, University of Wisconsin, Madison. pCAR-ΔCrtX was kindly provided by E.T. Wurtzel at the City University of New York, which contains CrtE, B, I, Y and Z from Erwinia uredovora for zeaxanthin biosynthesis. The restriction enzymes and Phusion DNA polymerase were purchased from the New England Biolabs. Yeast YPAD medium-containing 1% yeast extract, 2% peptone and 2% dextrose supplied with 0.01% adenine hemisulphate was used to grow S. cerevisiae YSG50 strain. Synthetic complete drop-out medium lacking uracil (SC-Ura) was used to select transformants or integrants containing the assembled biochemical pathways of interest.