Crocetin Overproduction in Engineered via Tuning Key Enzymes Coupled With Precursor Engineering.

Crocetin, an important natural carotenoid dicarboxylic acid with high pharmaceutical values, has been successfully generated from glucose by engineered in our previous study. Here, a systematic optimization was executed for crocetin overproduction in yeast. The effects of precursor enhancement on crocetin production were investigated by blocking the genes involved in glyoxylate cycle [citric acid synthase () and malic acid synthase ()]. Crocetin titer was promoted by 50% by Δ compared to that of the starting strain. Then, the crocetin production was further increased by 44% through introducing the forward fusion enzymes of CrtZ (CrtZ from )-CCD2 (CCD2 from ). Consequently, the crocetin titer reached to 1.95 ± 0.23 mg/L by overexpression of CrtZ-CCD2 followed by medium optimization. Eventually, a titer of 12.43 ± 0.62 mg/L crocetin was achieved in 5-L bioreactor, which is the highest crocetin titer reported in micro-organisms.