Abstract: This invention provides improved biological synthesis of the apocarotenoid ?-ionone in Saccharomyces cerevisiae. The final native step involved in the natural apocarotenoid pathway depends on an endogenous farnesyl pyrophosphate synthase (FPPs). From there, heterologous geranylgeranyl pyrophosphate synthase (crtE), phytoene synthase (crtB), phytoene desaturase (crtI), lycopene ?-cyclase (LycE) and a Carotenoid Cleavage Dioxygenase (CCD1) are required to complete the synthesis of ?-ionone. Lycopene ?-cyclase from lettuce (Lactuca sativa) or modified cyclase from Arabidopsis thaliana was used to overproduce lycopene which was then cleaved by the carotenoid cleavage dioxygenase from Petunia hybrida (Ph-CCD1).