Fig. 4

Carotenoid synthesis by allantoin-induced switch. A Schematic design of allantoin-induced carotenoid synthesis. After deleting the Gal80 gene and substituting the Gal4 promoter with the DAL2 promoter, the JS-BE5-Allan strain exhibits responsiveness to allantoin signal for β-carotene production. IPP, isopentenyl pyrophosphate; DMAPP, dimethylallyl diphosphate; FPP, farnesyl pyrophosphate. B The color differences of carotenoid-producing strains on the normal YNBD plate (repression state) or YABD plate (activation state). Image was captured after 48 h cultivation. C The carotenoid levels of engineered yeast cells in normal YNBD medium (repression state) or YABD medium (activation state) after 96 h cultivation. D The cell growth profile of engineered yeast cells in normal YNBD medium (repression state) or YABD medium (activation state). All experiments were performed in triplicate, and data represent the mean values with standard deviations