Issue 38, 2014

Enhancement of whole cell dioxygenase biotransformations of haloarenes by toxic ionic liquids

Abstract

Accessing chirally pure cis-diols from arenes using micro-organisms over-expressing toluene dioxygenase (TDO) is now well established, but the conversions remain low for the more toxic and volatile substrates. For such arenes, improved production has already been achieved in the presence of hydrophobic non-toxic ionic liquids (ILs) acting in the form of a reservoir for the arene substrate. Yet, the costs associated with such ILs require extensive process development to render them viable. Herein, we show that optimization of the hydrophobic IL's cationic moiety and of the IL's concentration are key to enhanced conversion yielding between a 2–5 fold yield increase in the conversion of four haloarenes (Ph–X; X = F, Cl, Br, I). Additionally, we report that hydrophilic imidazolium-based ILs offer opportunities to achieve similarly high yielding biotransformations, with further improved reaction rates (<6 h), and this at very low ILs' concentrations (0.0015 VIL/Vaq). We also demonstrate that the increased biotransformations are due to these ILs being inhibitors of cellular respiration processes and thus favoring the shunting of NADH and O2 towards the overexpressed biocatalytic process.

Graphical abstract: Enhancement of whole cell dioxygenase biotransformations of haloarenes by toxic ionic liquids

Supplementary files

Article information

Article type
Paper
Submitted
22 Jan 2014
Accepted
04 Apr 2014
First published
08 Apr 2014

RSC Adv., 2014,4, 19916-19924

Author version available

Enhancement of whole cell dioxygenase biotransformations of haloarenes by toxic ionic liquids

C. C. R. Allen, C. J. Boudet, C. Hardacre and M. E. Migaud, RSC Adv., 2014, 4, 19916 DOI: 10.1039/C4RA00640B

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