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Expanding Upon Styrene Biosynthesis to Engineer a Novel Route to 2‐Phenylethanol
Author(s) -
Machas Michael S.,
McKenna Rebekah,
Nielsen David R.
Publication year - 2017
Publication title -
biotechnology journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.144
H-Index - 84
eISSN - 1860-7314
pISSN - 1860-6768
DOI - 10.1002/biot.201700310
Subject(s) - heterologous , styrene , escherichia coli , chemistry , biochemistry , yeast , biosynthesis , phenylalanine , mevalonate pathway , enzyme , gene , organic chemistry , amino acid , copolymer , polymer
2‐Phenylethanol (2PE) is a key molecule used in the fragrance and food industries, as well as a potential biofuel. In contrast to its extraction from plant biomass and/or more common chemical synthesis, microbial 2PE production has been demonstrated via both native and heterologous expression of the yeast Ehrlich pathway. Here, a novel alternative to this established pathway is systematically engineered in Escherichia coli and evaluated as a more robust and efficient route. This novel pathway is constructed via the modular extension of a previously engineered styrene biosynthesis pathway, proceeding from endogenous l ‐phenylalanine in five steps and involving four heterologous enzymes. This “styrene‐derived” pathway boasts nearly a 10‐fold greater thermodynamic driving force than the Ehrlich pathway, and enables reduced accumulation of acetate byproduct. When directly compared using a host strain engineered for l ‐phenylalanine over‐production, preservation of phosphoenolpyruvate, and reduced formation of byproduct 2‐phenylacetic acid, final 2PE titers via the styrene‐derived and Ehrlich pathways reached 1817 and 1164 mg L −1 , respectively, at yields of 60.6 and 38.8 mg g −1 . Following optimization of induction timing and initial glucose loading, 2PE titers by the styrene‐derived pathway approached 2 g L −1 – nearly a two‐fold twofold increase over prior reports for 2PE production by E. coli employing the Ehrlich pathway.