Reconstruction of tyrosol synthetic pathways in Escherichia coli

Tyrosol is a pharmacologically active phenolic compound widely used in the medicine and chemical industries.Traditional methods of plant extraction are complicated and chemical synthesis of tyrosol is not commercially viable. In this study, a recombinant Escherichia coli strain was constructed by overexpressing the phenylpyruvate decarboxylase ARO10 from Saccharomyces cerevisiae, which could produce tyrosol from glucose. Furthermore,genes encoding key enzymes from the competing phenylalanine and tyrosine synthesis pathways and the repression protein TyrR were eliminated, and the resulting engineered strain generated 3.57 mmol·L-1 tyrosol from glucose. More significantly, codon optimization of ARO10 increased expression and tyrosol titer. Using the novel engineered strain expressing codon-optimized AR10 in shake-flask culture, 8.72 mmol·L-1 tyrosol was obtained after 48 h. Optimization of the induction conditions improved tyrosol production to 9.53 mmol·L-1(1316.3 mg·L-1). A higher titer of tyrosol was achieved by reconstruction of tyrosol synthetic pathway in E. coli.