Engineering Eschericha coli for Enhanced Tyrosol Production

Abstract

Tyrosol is a phenolic compound found in olive oil and wines. The health benefits of tyrosol have attracted considerable attention. Because the tyrosol extraction from plants poses a major obstacle, biosynthesizing this compound using microbial hosts is of interest. In this study, the phenylpyruvate decarboxylase gene ARO10 and the aromatic amino acid aminotransferase gene ARO8 were introduced into Escherichia coli to generate two recombinant tyrosol producers. Deleting the prephenate dehydratase gene pheA and the phenylacetaldehyde dehydrogenase gene feaB improved the tyrosol production. Under the optimal fermentation conditions, a recombinant strain overexpressing ARO10 gene produced 4.15 mM tyrosol from 1% (w/v) glucose during a 48 h shake flask cultivation. Furthermore, when tyrosine was used as the substrate, the recombinant strain co-overexpressing ARO8 and ARO10 genes displayed a higher tyrosol yield, in which 8.71 mM tyrosol was produced from 10 mM tyrosine. This investigation suggests that microbial tyrosol production has application potential.

Building microbial factories for the production of aromatic amino acid pathway derivatives: From commodity chemicals to plant-sourced natural products

“…The resulting strain produced tyrosol at 573 mg/L from glucose. When 1.8 g/L L-Tyr was used as the substrate, the whole-cell conversion produced 1.2 g/L of tyrosol, wherein the aromatic amino acid aminotransferase Aro8 from S. cerevisiae was expressed to enhance the conversion of L-Tyr to 4hydroxyphenylpyruvate (Xue et al, 2017). In a later study, Li et al incorporated both ARO10…”

“…(48 h) Whole cell conversion (20 h) Xue et al, 2017 1203 mg/L tyrosol was produced in the whole cell conversion when 1.8 g/L L-Tyr was used as the substrate.…”

Expanding the repertoire of aromatic chemicals by microbial production

“…However, the highest titer only reached 7.7 mmol L −1 for 2-phenylethanol and 8.3 mmol L −1 for tyrosol. 76,77 The formation of 2-phenylacetic acid and 4-hydroxyphenylacetic acid also was achieved by overexpression of endogenous feaB in E. coli using the Ehrlich pathway intermediates phenylacetaldehyde and 4-hydroxyphenylacetaldehyde as precursors, respectively. 75 The biosynthetic pathway of 2-phenylethanol also is regulated by the general amino acid permease and GATA transcription factors.…”

“…40 The whole-cell conversion of L-Phe or L-Tyr to 2-phenylethanol or tyrosol also has been extensively studied in E. coli and S. cerevisiae, as an alternative way to overcome the low yields of de novo biosynthesis. 76,77 The formation of 2-phenylacetic acid and 4-hydroxyphenylacetic acid also was achieved by overexpression of endogenous feaB in E. coli using the Ehrlich pathway intermediates phenylacetaldehyde and 4-hydroxyphenylacetaldehyde as precursors, respectively. 41 Many reports have described microbial production of trans-cinnamic acid and p-hydroxycinnamic acid, which are the deaminated derivatives of L-Phe and L-Tyr, respectively.…”

Current Status of Microbial Phenylethanoid Biosynthesis

“…Using this system, 0.5 mM tyrosol was synthesized [42]. In another study, Aro8 and Aro10 from S. cerevisiae were overexpressed in E. coli and pheA and feaB were deleted, resulting in the synthesis of 4.15 mM tyrosol upon supplying 10 mM tyrosine [43]. By introducing the bifunctional gene AAS into E. coli and engineering the E. coli tyrosine biosynthesis pathway to increase intracellular tyrosine concentration by deleting tyrR and pheA, 3.77 mM tyrosol was synthesized [44].…”