title: Butanol production in S. cerevisiae via a synthetic ABE pathway is enhanced by specific metabolic engineering and butanol resistance.
abstract: BACKGROUND
  The fermentation of sugars to alcohols by microbial systems underpins many biofuel initiatives. Short chain alcohols, like n-butanol, isobutanol and isopropanol, offer significant advantages over ethanol in terms of fuel attributes. However, production of ethanol from resistant Saccharomyces cerevisiae strains is significantly less complicated than for these alternative alcohols.
  
  
  RESULTS
  In this study, we have transplanted an n-butanol synthesis pathway largely from Clostridial sp. to the genome of an S. cerevisiae strain. Production of n-butanol is only observed when additional genetic manipulations are made to restore any redox imbalance and to drive acetyl-CoA production. We have used this butanol production strain to address a key question regarding the sensitivity of cells to short chain alcohols. In the past, we have defined specific point mutations in the translation initiation factor eIF2B based upon phenotypic resistance/sensitivity to high concentrations of exogenously added n-butanol. Here, we show that even during endogenous butanol production, a butanol resistant strain generates more butanol than a butanol sensitive strain.
  
  
  CONCLUSIONS
  These studies demonstrate that appreciable levels of n-butanol can be achieved in S. cerevisiae but that significant metabolic manipulation is required outside of the pathway converting acetyl-CoA to butanol. Furthermore, this work shows that the regulation of protein synthesis by short chain alcohols in yeast is a critical consideration if higher yields of these alcohols are to be attained.
authors.affiliation: The Faculty of Life Sciences, The Michael Smith Building, The University of Manchester, Oxford Rd., Manchester, M13 9PT UK.
authors.forename: R
authors.initials: R
authors.lastname: Swidah
authors.affiliation: The Faculty of Life Sciences, The Michael Smith Building, The University of Manchester, Oxford Rd., Manchester, M13 9PT UK.
authors.forename: H
authors.initials: H
authors.lastname: Wang
authors.affiliation: The Faculty of Life Sciences, The Michael Smith Building, The University of Manchester, Oxford Rd., Manchester, M13 9PT UK.
authors.forename: P J
authors.initials: PJ
authors.lastname: Reid
authors.affiliation: The Faculty of Life Sciences, The Michael Smith Building, The University of Manchester, Oxford Rd., Manchester, M13 9PT UK.
authors.forename: H Z
authors.initials: HZ
authors.lastname: Ahmed
authors.affiliation: School of Chemical engineering and Analytical Science, The Mill, The University of Manchester, Sackville St., Manchester, M139PL UK.
authors.forename: A M
authors.initials: AM
authors.lastname: Pisanelli
authors.affiliation: School of Chemical engineering and Analytical Science, The Mill, The University of Manchester, Sackville St., Manchester, M139PL UK.
authors.forename: K C
authors.initials: KC
authors.lastname: Persaud
authors.affiliation: The Faculty of Life Sciences, The Michael Smith Building, The University of Manchester, Oxford Rd., Manchester, M13 9PT UK.
authors.forename: C M
authors.initials: CM
authors.lastname: Grant
authors.affiliation: The Faculty of Life Sciences, The Michael Smith Building, The University of Manchester, Oxford Rd., Manchester, M13 9PT UK.
authors.forename: M P
authors.initials: MP
authors.lastname: Ashe
keywords: ABE pathway; Biobutanol; Saccharomyces cerevisiae