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Production of Natural 2-Phenylethanol from Glucose or Glycerol with Coupled Escherichia coli Strains Expressing l-Phenylalanine Biosynthesis Pathway and Artificial Biocascades

Sekar, Balaji Sundara, Lukito, Benedict Ryan, Li, Zhi
ACS sustainable chemistry & engineering 2019 v.7 no.14 pp. 12231-12239
Escherichia coli, biosynthesis, biotransformation, cosmetics, glucose, glycerol, odors, phenylalanine, phenylethyl alcohol, prices, temperature
2-Phenylethanol (2-PE) is a fragrance widely used in food and cosmetics. Natural 2-PE is preferred in these applications but with high price and very limited availability. Microbial synthesis from glucose or glycerol is an attractive way to produce natural 2-PE, but suffers from low product titer. Escherichia coli NST74-Phe-Sty was engineered to coexpress the l-phenylalanine (l-Phe) biosynthesis pathway and enzyme cascade of l-Phe to 2-PE, producing only 0–0.17 g/L 2-PE from glucose at 22–37 °C due to the incompatibility of the temperature for enzyme expression and activity. Enhanced production of 2-PE (8.4–9.1 g/L) from glucose or glycerol was achieved by coupling of E. coli NST74-Phe expressing the l-Phe biosynthesis pathway for l-Phe production at the optimal temperature of 37 °C with E. coli T7-Sty expressing enzyme cascades of l-Phe to 2-PE at the optimal expression temperature of 22 °C and the optimal biotransformation temperature of 30 °C. The 2-PE titer is 4.7-fold higher than the best reported 2-PE concentration produced from glucose. The coupled strains approach could be generally applicable for enhancing microbial production of useful chemicals from sugars or glycerol.