Construction and optimization of baicalein synthesis pathway from phenylalanine in Saccharomyces cerevisiae

In order to efficiently prepare baicalein using synthetic biology techniques, a synthesis pathway of baicalein was constructed based on the synthetic chassis cell Ch-9 from Saccharomyces cerevisiae, which synthesizes chrysin. The coenzyme A ligase (4CL) mutant 4AT and the homologous enzyme CLL-7 gene from the Arabidopsis thaliana were integrated into the PAD1 gene site of the cinnamic acid decarboxylase. Gene substitution knockout was achieved through homologous recombination, and the yield of chrysin in shake flask fermentation of strain BA-C2-1 was 40.21 mg/L. The alkenyl reductase gene MdECR from apples was integrated and replaced into DBR gene site in S. cerevisiae, and enhance the expression of the ACS gene for acetyl CoA synthase to increase the supply of acetyl CoA. The results showed that the yield of chrysin by shake flask fermentation of recombinant yeast strain BA-C3-4 was 70.25 mg/L, which was 7.2 times higher than that of the original chassis cell Ch-9; After enhancing the expression of ACS gene and acetyl CoA, the yeast strain BA-C4-22 produced chrysin 125.04 mg/L in shake flask fermentation, which was 1.78 times higher than the experimental group without enhanced expression of ACS gene; Finally, the BA-C4-22 strain was integrated with the SbaiCYP82D4 gene and ART2 gene, to extend the synthesis endpoint to baicalein, the yield of baicalein in fermentation broth of strain BA-B1-5 was 70.94 mg/L.