title: Comparison between Escherichia coli K-12 strains W3110 and MG1655 and wild-type E. coli B as platforms for xylitol production.
abstract: Escherichia coli W3110 was previously engineered to produce xylitol from a mixture of glucose plus xylose by expressing xylose reductase (CbXR) and deleting xylulokinase (DeltaxylB), combined with either plasmid-based expression of a xylose transporter (XylE or XylFGH) (Khankal et al., J Biotechnol, 2008) or replacing the native crp gene with a mutant (crp*) that alleviates glucose repression of xylose transport (Cirino et al., Biotechnol Bioeng 95:1167-1176, 2006). In this study, E. coli K-12 strains W3110 and MG1655 and wild-type E. coli B were compared as platforms for xylitol production from glucose-xylose mixtures using these same strategies. The engineered strains were compared in fed-batch fermentations and as non-growing resting cells. Expression of CRP* in the E. coli B strains tested was unable to enhance xylose uptake in the presence of glucose. Xylitol production was similar for the (crp*, DeltaxylB)-derivatives of W3110 and MG1655 expressing CbXR (average specific productivities of 0.43 g xylitol g cdw(-1 ) h(-1) in fed-batch fermentation). In contrast, results varied substantially between different DeltaxylB-derivative strains co-expressing either XylE or XylFGH. The differences in genetic background between these host strains can therefore profoundly influence metabolic engineering strategies.
authors.affiliation: Department of Chemical Engineering, Pennsylvania State University, University Park, PA 16802, USA.
authors.forename: Reza
authors.initials: R
authors.lastname: Khankal
authors.forename: Francesca
authors.initials: F
authors.lastname: Luziatelli
authors.forename: Jonathan W
authors.initials: JW
authors.lastname: Chin
authors.forename: Christopher S
authors.initials: CS
authors.lastname: Frei
authors.forename: Patrick C
authors.initials: PC
authors.lastname: Cirino
mesh_terms: D001711:Biotransformation; D050260:Carbohydrate Metabolism; D003470:Culture Media; D002373:Cyclic AMP Receptor Protein / Q000235:genetics / Q000378:metabolism; D004926:Escherichia coli / Q000145:classification / Q000166:cytology* / Q000378:metabolism*; D005285:Fermentation; D005947:Glucose / Q000378:metabolism; D009004:Monosaccharide Transport Proteins / Q000378:metabolism; D013997:Time Factors; D014993:Xylitol / Q000096:biosynthesis*; D014994:Xylose / Q000378:metabolism
chemical_list: D003470:Culture Media; D002373:Cyclic AMP Receptor Protein; D009004:Monosaccharide Transport Proteins; D014994:Xylose; D005947:Glucose; D014993:Xylitol