One‐Pot Production of Natural 2‐Phenylethanol from L‐Phenylalanine via Cascade Biotransformations

Abstract

Abstract2‐Phenylethanol (2‐PE) is an aroma compound with a rose‐like odors widely used as food ingredient, and natural 2‐PE is much preferred for the application with high selling price but limited availability. Bioproduction of 2‐PE from bioresources could provide a green, sustainable, and economic process to manufacture natural 2‐PE. Here we report a novel artificial cascade biotransformation to convert bioderived L‐phenylalanine (L‐Phe) to natural 2‐PE via deamination, decarboxylation, epoxidation, isomerization, and reduction in one pot. Recombinant E. coli strains co‐expressing the 5 necessary enzymes were engineered by using double plasmids, modular approach, and random combination as highly active, easily available, and recyclable biocatalysts. Two‐phase biotransformation with E. coli (RE) cells using biodiesel, a green and easily available solvent for in situ product extraction to minimize the inhibition, significantly improved product concentration and yield, converting 80 mM of L‐Phe to 71 mM (8.8 g/L, 89 % yield) of 2‐PE. The inhibition of 2‐PE was also reduced through in‐situ product adsorption using XAD4 resins. Using XAD4‐biodiesel‐aqueous buffer 3‐phase system could further enhance the concentration of 2‐PE to 85 mM (10.4 g/L, 85 % yield). The developed artificial cascade biotransformation of L‐Phe to 2‐PE is much better than other reported bioproductions of 2‐PE and provides high‐yielding, sustainable, and potentially practical synthesis of high‐value natural 2‐PE.