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

Tianqing Song; Nan Wu; Chen Wang; Ying Wang; Fenghua Chai; Mingzhu Ding; Xia Li; Mingdong Yao; Wenhai Xiao; Yingjin Yuan

doi:10.3389/fbioe.2020.578005

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

Front Bioeng Biotechnol. 2020 Sep 4:8:578005. doi: 10.3389/fbioe.2020.578005. eCollection 2020.

Authors

Tianqing Song^{1

2}, Nan Wu^{1

2}, Chen Wang^{1

2}, Ying Wang^{1

2}, Fenghua Chai^{1

2}, Mingzhu Ding^{1

2}, Xia Li^{1

2}, Mingdong Yao^{1

2}, Wenhai Xiao^{1

2}, Yingjin Yuan^{1

2}

Affiliations

¹ Frontier Science Center for Synthetic Biology, Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Tianjin, China.
² Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin University, Tianjin, China.

Abstract

Crocetin, an important natural carotenoid dicarboxylic acid with high pharmaceutical values, has been successfully generated from glucose by engineered Saccharomyces cerevisiae 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 (CIT2) and malic acid synthase (MLS1)]. Crocetin titer was promoted by 50% by ΔCIT2 compared to that of the starting strain. Then, the crocetin production was further increased by 44% through introducing the forward fusion enzymes of PsCrtZ (CrtZ from Pantoea stewartii)-CsCCD2 (CCD2 from Crocus sativus). Consequently, the crocetin titer reached to 1.95 ± 0.23 mg/L by overexpression of PsCrtZ-CsCCD2 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.

Keywords: Saccharomyces cerevisiae; crocetin; enzyme fusion; metabolic engineering; precursor engineering.