title: Improved n-butanol tolerance in Escherichia coli by controlling membrane related functions.
abstract: 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.
authors: Department of Biological Sciences, Korea Advanced Institute of Science and Technology, 291 Daehak-ro, Yuseong-gu, Daejeon 305-701, Republic of Korea.
authors: Le Minh
authors: le M
authors: Bui
authors: Department of Biological Sciences, Korea Advanced Institute of Science and Technology, 291 Daehak-ro, Yuseong-gu, Daejeon 305-701, Republic of Korea.
authors: Ju Young
authors: JY
authors: Lee
authors: Department of Biological Sciences, Korea Advanced Institute of Science and Technology, 291 Daehak-ro, Yuseong-gu, Daejeon 305-701, Republic of Korea.
authors: Almando
authors: A
authors: Geraldi
authors: Department of Biological Sciences, Korea Advanced Institute of Science and Technology, 291 Daehak-ro, Yuseong-gu, Daejeon 305-701, Republic of Korea.
authors: Ziaur
authors: Z
authors: Rahman
authors: Department of Biological Sciences, Korea Advanced Institute of Science and Technology, 291 Daehak-ro, Yuseong-gu, Daejeon 305-701, Republic of Korea.
authors: Jun Hyoung
authors: JH
authors: Lee
authors: Department of Biological Sciences, Korea Advanced Institute of Science and Technology, 291 Daehak-ro, Yuseong-gu, Daejeon 305-701, Republic of Korea. Electronic address: sunkim@kaist.ac.kr.
authors: Sun Chang
authors: SC
authors: Kim
mesh_terms: D020001:1-Butanol / Q000378:metabolism*; D000222:Adaptation, Physiological / Q000502:physiology*; D053898:Biosynthetic Pathways / Q000235:genetics* / Q000502:physiology; D017931:DNA Primers / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics* / Q000502:physiology; D029968:Escherichia coli Proteins / Q000378:metabolism; D064429:Fatty Acid Synthases / Q000378:metabolism; D005285:Fermentation; D007218:Industrial Microbiology / Q000379:methods*; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D060847:Metabolic Engineering / Q000379:methods*; D010957:Plasmids / Q000235:genetics
chemical_list: D017931:DNA Primers; D029968:Escherichia coli Proteins; D026901:Membrane Transport Proteins; C100775:feo protein, E coli; D020001:1-Butanol; D064429:Fatty Acid Synthases
keywords: ATF; Membrane; SrpABC; Tolerance; cis-Vaccenic acid; n-Butanol