De novo biosynthesis of phenylpyruvic acid by engineered Escherichia coli

Phenylpyruvic acid is a high-value α-keto acid with broad applications in pharmaceutical and chemical industries. Traditional production via chemical synthesis or transaminase-mediated L-phenylalanine conversion is limited by cost and environmental concerns. Four biosynthetic schemes for phenylpyruvic acid production were evaluated. In scheme 1a, growing cells converted shikimic acid to phenylpyruvic acid, yielding 0.15 g/L. In scheme 1b, major transaminases were deleted in an L-phenylalanine producing strain, yielding 0.21 g/L PPA. In scheme 1c, a "shuttle-run" strategy was applied, with a temperature sensitive pR promoter regulating membrane-associated L-amino acid deaminase, achieving 0.98 g/L. Finally (scheme 1d), a dual strain "fermentation-enzyme biocatalysis" coupled system combined WP-06-1 with W-03-3, decoupling precursor accumulation from enzymatic conversion and producing 10.21 g/L phenylpyruvic acid, the highest reported from glucose without exogenous L-phenylalanine, providing an efficient and sustainable platform for phenylpyruvic acid biomanufacturing.