title: Engineering and comparison of non-natural pathways for microbial phenol production.
abstract: The non-renewable petrochemical phenol is used as a precursor to produce numerous fine and commodity chemicals, including various pharmaceuticals and phenolic resins. Microbial phenol biosynthesis has previously been established, stemming from endogenous tyrosine via tyrosine phenol lyase (TPL). TPL, however, suffers from feedback inhibition and equilibrium limitations, both of which contribute to reduced flux through the overall pathway. To address these limitations, two novel and non-natural phenol biosynthesis pathways, both stemming instead from chorismate, were constructed and comparatively evaluated. The first proceeds to phenol in one heterologous step via the intermediate p-hydroxybenzoic acid, while the second involves two heterologous steps and the associated intermediates isochorismate and salicylate. Maximum phenol titers achieved via these two alternative pathways reached as high as 377 ± 14 and 259 ± 31 mg/L in batch shake flask cultures, respectively. In contrast, under analogous conditions, phenol production via the established TPL-dependent route reached 377 ± 23 mg/L, which approaches the maximum achievable output reported to date under batch conditions. Additional strain development and optimization of relevant culture conditions with respect to each individual pathway is ultimately expected to result in further improved phenol production. Biotechnol. Bioeng. 2016;113: 1745-1754. © 2016 Wiley Periodicals, Inc.
authors.affiliation: Chemical Engineering, School for Engineering of Matter, Transport, and Energy, University of Arizona State, Tempe, Arizona.
authors.forename: Brian
authors.initials: B
authors.lastname: Thompson
authors.affiliation: Chemical Engineering, School for Engineering of Matter, Transport, and Energy, University of Arizona State, Tempe, Arizona.
authors.forename: Michael
authors.initials: M
authors.lastname: Machas
authors.affiliation: Chemical Engineering, School for Engineering of Matter, Transport, and Energy, University of Arizona State, Tempe, Arizona. david.r.nielsen@asu.edu.
authors.forename: David R
authors.initials: DR
authors.lastname: Nielsen
mesh_terms: D001419:Bacteria / Q000201:enzymology* / Q000235:genetics*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D061249:Batch Cell Culture Techniques; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D005947:Glucose / Q000378:metabolism; D060847:Metabolic Engineering / Q000379:methods*; D053858:Metabolic Networks and Pathways; D019800:Phenol / Q000378:metabolism*; D014443:Tyrosine / Q000378:metabolism; D014447:Tyrosine Phenol-Lyase / Q000235:genetics / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D019800:Phenol; D014443:Tyrosine; D014447:Tyrosine Phenol-Lyase; D005947:Glucose
keywords: aromatics; chorismate; p-hydroxybenzoate; phenol; salicylate; tyrosine