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

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

JOURNAL=Frontiers in Bioengineering and Biotechnology

VOLUME=8

YEAR=2020

URL=https://www.frontiersin.org/journals/bioengineering-and-biotechnology/articles/10.3389/fbioe.2020.578005

DOI=10.3389/fbioe.2020.578005

ISSN=2296-4185

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