title: Supplementation of intracellular XylR leads to coutilization of hemicellulose sugars.
abstract: Escherichia coli has the potential to be a powerful biocatalyst for the conversion of lignocellulosic biomass into useful materials such as biofuels and polymers. One important challenge in using E. coli for the transformation of biomass sugars is diauxie, or sequential utilization of different types of sugars. We demonstrate that, by increasing the intracellular levels of the transcription factor XylR, the preferential consumption of arabinose before xylose can be eliminated. In addition, XylR augmentation must be finely tuned for robust coutilization of these two hemicellulosic sugars. Using a novel technique for scarless gene insertion, an additional copy of xylR was inserted into the araBAD operon. The resulting strain was superior at cometabolizing mixtures of arabinose and xylose and was able to produce at least 36% more ethanol than wild-type strains. This strain is a useful starting point for the development of an E. coli biocatalyst that can simultaneously convert all biomass sugars.
authors.affiliation: Joint BioEnergy Institute, Emeryville, California, USA.
authors.forename: Dan
authors.initials: D
authors.lastname: Groff
authors.forename: Peter I
authors.initials: PI
authors.lastname: Benke
authors.forename: Tanveer S
authors.initials: TS
authors.lastname: Batth
authors.forename: Gregory
authors.initials: G
authors.lastname: Bokinsky
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Petzold
authors.forename: Paul D
authors.initials: PD
authors.lastname: Adams
authors.forename: Jay D
authors.initials: JD
authors.lastname: Keasling
mesh_terms: D001089:Arabinose / Q000378:metabolism*; D056804:Biofuels; D001709:Biotechnology / Q000379:methods*; D003470:Culture Media / Q000737:chemistry; D004926:Escherichia coli / Q000254:growth & development* / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D000431:Ethanol / Q000378:metabolism; D005285:Fermentation; D015964:Gene Expression Regulation, Bacterial; D015971:Gene Expression Regulation, Enzymologic; D011134:Polysaccharides / Q000737:chemistry / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014994:Xylose / Q000378:metabolism*
chemical_list: D056804:Biofuels; D003470:Culture Media; D029968:Escherichia coli Proteins; D011134:Polysaccharides; D014157:Transcription Factors; D000431:Ethanol; C007916:hemicellulose; D014994:Xylose; D001089:Arabinose