Figure 2

Schematic representation of X. dendrorhous mutant strains. (A) In the mutant XdCop6, the native astaxanthin pathway has not been modified but the gene Cop6 has been integrated in the rDNA of the yeast allowing the mutant to produce both astaxanthin and α-cuprenene. (B) In the strain ΔE-Cop6 the Cop6 gene has been inserted in the crtE gene causing the disruption of the carotenoid production at the GGPP synthesis level. (C) When Cop6 is inserted in the crtYB gene, the ΔYB-Cop6 strain is created. While there is still expression of the GGPPS, phytoene cannot be produced anymore, blocking the production of astaxanthin one step downstream of the ΔE-Cop6.