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Byproduct-free geraniol glycosylation by whole-cell biotransformation with recombinant Escherichia coli.

Authors
  • Priebe, Xenia1, 2
  • Hoang, Manh Dat1
  • Rüdiger, Julian3
  • Turgel, Maria1
  • Tröndle, Julia1
  • Schwab, Wilfried3
  • Weuster-Botz, Dirk4
  • 1 Department of Mechanical Engineering, Institute of Biochemical Engineering, Technical University of Munich, Boltzmannstr. 15, 85748, Garching, Germany. , (Germany)
  • 2 Bioprocess Technology, Evonik Operations GmbH, Rodenbacher Chaussee 4, 63457, Hanau-Wolfgang, Germany. , (Germany)
  • 3 School of Life Sciences Weihenstephan, Biotechnology of Natural Products, Technical University of Munich, Liesel-Beckmann-Str. 1, 85354, Freising, Germany. , (Germany)
  • 4 Department of Mechanical Engineering, Institute of Biochemical Engineering, Technical University of Munich, Boltzmannstr. 15, 85748, Garching, Germany. [email protected] , (Germany)
Type
Published Article
Journal
Biotechnology Letters
Publisher
Springer-Verlag
Publication Date
Jan 01, 2021
Volume
43
Issue
1
Pages
247–259
Identifiers
DOI: 10.1007/s10529-020-02993-z
PMID: 32860164
Source
Medline
Keywords
Language
English
License
Unknown

Abstract

Geraniol, a fragrance of great importance in the consumer goods industry, can be glucosylated by the UDP-glucose-dependent glucosyltransferase VvGT14a from Vitis vinifera, yielding more stable geranyl glucoside. Escherichia coli expressing VvGT14a is a convenient whole-cell biocatalyst for this biotransformation due to its intrinsic capability for UDP-glucose regeneration. The low water solubility and high cytotoxicity of geraniol can be overcome in a biphasic system where the non-aqueous phase functions as an in situ substrate reservoir. However, the effect of different process variables on the biphasic whole-cell biotransformation is unknown. Thus, the goal of this study was to identify potential bottlenecks during biotransformation with in situ geraniol supply via isopropyl myristate as second non-aqueous phase. First, insufficient UDP-glucose supply could be ruled out by measurement of intracellular UDP-glucose concentrations. Instead, oxygen supply was determined as a bottleneck. Moreover, the formation of the byproduct geranyl acetate by chloramphenicol acetyltransferase (CAT) was identified as a constraint for high product yields. The use of a CAT-deficient whole-cell biocatalyst prevented the formation of geranyl acetate, and geranyl glucoside could be obtained with 100% selectivity during a biotransformation on L-scale. This study is the first to closely analyze the whole-cell biotransformation of geraniol with Escherichia coli expressing an UDP-glucose-dependent glucosyltransferase and can be used as an optimal starting point for the design of other glycosylation processes.

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