For heterologous synthesize natural carotenoid zeaxanthin in microorganism,a β-carotene producing Saccharomyces cerevisiae was chozen as the host cell to construct engineered yeast with synthetic biology method.The key enzymes β-carotene hydroxylase encoding gene CrtZ from nine sources were integrated in the chromosomal,separately.As the result,the strain carrying CrtZ from Erwinia uredovora achieved the highest titer of zeaxanthin.Moreover,the conversion from farnesyl pyrophosphate (an important precursor for terpenoid natural products) to farnesol was reduced by knocking out gene Lpp1 and Dpp1,providing more precursors for zeaxanthin synthesis.The zeaxanthin yield increased 1.27 fold (from 29 mg/L to 36.8 mg/L) accordingly.Furthermore,a titer of zeaxanthin was achieved as 96.2 mg/L in shake-flask through increasing the CrtZ gene copy number and regulating its promoter's activity,which is the highest reported microbial titer known.
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