Artificial Biological Funnel Design Enabled Valorization of Aromatic Derivatives into Catechol

Aromatic resources, including lignin-, petroleum-, and plastic-derived aromatic compounds, show great potential as feedstocks for producing aromatic fine chemicals. However, the heterogeneity of lignin and the complex conversion pathways of these aromatic derivatives hinder their value enhancement. In this study, an engineered <i>Pseudomonas putida</i> KT2440 was developed to efficiently convert diverse aromatic derivatives into catechol with an atom-economic conversion. By screening and expressing heterologous protocatechuate decarboxylases, a "biological funnel" pathway was constructed, successfully converting lignin-derived ferulic acid and <i>p</i>-coumaric acid into catechol. Expressing the rate-limiting enzymes of VanAB and PobA minimized the accumulation of intermediates, such as vanillic acid and <i>p</i>-hydroxybenzoic acid, producing a catechol titer of 8.8 mM. A cofactor regeneration strategy for protocatechuate decarboxylases enhanced their activity, achieving a catechol titer of 14.1 mM with a molar yield of 98.5%. Additionally, catechol-producing "biological funnels" were established by covalorizing diverse aromatic substrates, including phenol, guaiacol, sodium benzoate, and terephthalic acid. Artificial microbial consortia subsequently consumed these heterogeneous substrates and facilitated efficient catechol production. Overall, the design of artificial biological funnels and microbial consortia enabled the valorization of heterogeneous aromatic derivatives into catechol, providing a sustainable valorization route of these aromatic resources toward aromatic fine chemicals.