title: Construction of a novel phenol synthetic pathway in Escherichia coli through 4-hydroxybenzoate decarboxylation.
abstract: Phenol is a bulk chemical with lots of applications in the chemical industry. Fermentative production of phenol had been realized in both Pseudomonas putida and Escherichia coli by recruiting tyrosine phenol-lyase (TPL). The TPL pathway needs tyrosine as the direct precursor for phenol production. In this work, a novel phenol synthetic pathway was created in E. coli by recruiting 4-hydroxybenzoate decarboxylase, which can convert 4-hydroxybenzoate to phenol and carbon dioxide. Activating 3-deoxy-D-arabino-heptulosonate-7-phosphate (DAHP) synthase and chorismate pyruvate lyase (UbiC) through plasmid overexpression led to 7- and 69-fold increase of phenol production, respectively, demonstrating that these two enzymes were the rate-limiting steps for phenol production. Genetically stable strains were then obtained by gene integration and gene modulation directly in chromosome. Phenol titer increased 147-fold (from 1.7 to 250 mg/L) after modulating the DAHP synthase, UbiC, and 4-hydroxybenzoate decarboxylase genes in chromosome. Five solvents were tested for two-phase extractive fermentation to eliminate phenol toxicity to E. coli cells. Tributyrin and dibutyl phthalate were the best two solvents for improving phenol production, leading to 23 and 30 % increase of total phenol production, respectively. Two-phase fed-batch fermentation of the best strain Phe009 was performed in a 7 L fermentor, which produced 9.51 g/L phenol with a yield of 0.061 g/g glucose.
authors.affiliation: Tianjin University of Science & Technology, 300457, Tianjin, China.
authors.forename: Liangtian
authors.initials: L
authors.lastname: Miao
authors.forename: Qingyan
authors.initials: Q
authors.lastname: Li
authors.forename: Aipo
authors.initials: A
authors.lastname: Diao
authors.forename: Xueli
authors.initials: X
authors.lastname: Zhang
authors.forename: Yanhe
authors.initials: Y
authors.lastname: Ma
mesh_terms: D053898:Biosynthetic Pathways; D003653:Decarboxylation; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism*; D005285:Fermentation; D005947:Glucose / Q000378:metabolism; D060847:Metabolic Engineering; D010226:Parabens / Q000378:metabolism*; D019800:Phenol / Q000378:metabolism*
chemical_list: D010226:Parabens; D019800:Phenol; D005947:Glucose; C038193:4-hydroxybenzoic acid