Increased Production of Dicinnamoylmethane Via Improving Cellular Malonyl-CoA Level by Using a CRISPRi in Escherichia coli.

Curcuminoids are natural phenylpropanoids that are biosynthesized via an L-phenylalanine metabolism pathway in turmeric (Curcuma longa L.). Curcuminoids have various chemopreventive activities and pharmaceutical applications in human life. In this study, we synthesized dicinnamoylmethane, one principal component of curcuminoids, from cinnamic acid by means of co-expression of Oryza sativa curcuminoid synthase and Petroselinum crispum 4-coumarate-CoA ligase in Escherichia coli BL21 (DE3). Moreover, we used CRISPRi systems to knock down the genes in a tricarboxylic acid cycle and fatty acid biosynthesis pathway. The repression of target genes led to an increase of up to 0.236 μmol g^-1 DCW of malonyl-CoA in cytosol-engineered E. coli and subsequently increased the biosynthesis of dicinnamoylmethane. We found that the S10 strain containing a CRISPRi repression for three genes, fabF, fabD, and mdh, showed the highest amount of dicinnamoylmethane of 7.54 μM, which is 5.76-fold higher than that of the wild-type strain. Finally, 41.94 μM (~ 11.6 mg) of dicinnamoylmethane was obtained in a 3-L fermenter.