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Improved n-butanol tolerance in Escherichia coli by controlling membrane related functions

Paper ID Volume ID Publish Year Pages File Format Full-Text
22802 43392 2015 12 PDF Available
Title
Improved n-butanol tolerance in Escherichia coli by controlling membrane related functions
Abstract

•fabA, fabB, fabD, fabF overexpression can increase cis-vaccenic acid (C18:1) proportion.•Pretreatment with C18:1, low temperature increase membrane C18:1 proportion.•Either method for increasing C18:1 can improve n-butanol tolerance.•SrpABC expressed in Escherichia coli can improve n-butanol tolerance.•FeoA, FabD can assist Artificial Transcription Factor to improve butanol tolerance.

As the increasing demand from both chemical and fuel markets, the interest in producing n-butanol using biological route has been rejuvenated to engineer an economical fermentation process, competing with the currently-dominant chemical synthesis. n-Butanol has been traditionally produced from the ABE fermentation of Clostridium acetobutylicum. This system, however, is not economically feasible due to its limited efficiency and the lack of genetic modification tools for further improvements. Alternatively, n-butanol synthesis pathway was successfully transferred into Escherichia coli and rapidly improved to reach a level of production comparable to the native producer. Nevertheless, the toxicity of n-butanol has become a common issue that either approach has to deal with. Previously, we reported our success in improving n-butanol tolerance in E. coli by engineering an Artificial Transcription Factor (ATF) that can modify the expression level of multiple targets simultaneously and improved the n-butanol tolerance of MG1655 strain to 1.5% (vol/vol) n-butanol. However, it was observed that some possible n-butanol tolerance mechanisms did not occurred upon the ATF expression, especially the membrane-related functions such as the homeoviscous adaptation, iron uptaking system, and efflux pump system. In this work, we attempted to enhance the n-butanol tolerance associated with the ATF by combining it with the membrane-related functions in E. coli, including the overexpression of fatty acid synthesis genes, iron-uptaking protein FeoA, and introducing a SrpABC efflux pump from Pseudomonas putida into E. coli. The synergistic effect of this combinatorial approach led to 4, 5, and 9-fold improved growths in the cultures containing 1, 1.5, and 2% (vol/vol) n-butanol, respectively, of an MG1655 knockout strain engineered for n-butanol production, and expanded the tolerance limit to 2% (vol/vol) n-butanol.

Keywords
n-Butanol; Tolerance; ATF; cis-Vaccenic acid; Membrane; SrpABC
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Improved n-butanol tolerance in Escherichia coli by controlling membrane related functions
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Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Biotechnology - Volume 204, 20 June 2015, Pages 33–44
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us