Accumulation of d-glucose from pentoses by metabolically engineered Escherichia coli.
Escherichia coli that is unable to metabolize d-glucose (with knockouts in ptsG, manZ, and glk) accumulates a small amount of d-glucose (yield of about 0.01 g/g) during growth on the pentoses d-xylose or l-arabinose as a sole carbon source. Additional knockouts in the zwf and pfkA genes, encoding, respectively, d-glucose-6-phosphate 1-dehydrogenase and 6-phosphofructokinase I (E. coli MEC143), increased accumulation to greater than 1 g/liter d-glucose and 100 mg/liter d-mannose from 5 g/liter d-xylose or l-arabinose. Knockouts of other genes associated with interconversions of d-glucose-phosphates demonstrate that d-glucose is formed primarily by the dephosphorylation of d-glucose-6-phosphate. Under controlled batch conditions with 20 g/liter d-xylose, MEC143 generated 4.4 g/liter d-glucose and 0.6 g/liter d-mannose. The results establish a direct link between pentoses and hexoses and provide a novel strategy to increase carbon backbone length from five to six carbons by directing flux through the pentose phosphate pathway.
BioChemical Engineering, College of Engineering, University of Georgia, Athens, Georgia, USA.
Tian
T
Xia
BioChemical Engineering, College of Engineering, University of Georgia, Athens, Georgia, USA.
Qi
Q
Han
BioChemical Engineering, College of Engineering, University of Georgia, Athens, Georgia, USA.
William V
WV
Costanzo
BioChemical Engineering, College of Engineering, University of Georgia, Athens, Georgia, USA.
Yixuan
Y
Zhu
Department of Chemistry, University of Georgia, Athens, Georgia, USA.
Jeffrey L
JL
Urbauer
BioChemical Engineering, College of Engineering, University of Georgia, Athens, Georgia, USA eiteman@engr.uga.edu.
Mark A
MA
Eiteman
D001089:Arabinose / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism; D005285:Fermentation; D005947:Glucose / Q000378:metabolism*; D005954:Glucosephosphate Dehydrogenase / Q000235:genetics / Q000378:metabolism; D008358:Mannose / Q000378:metabolism; D060847:Metabolic Engineering; D010427:Pentose Phosphate Pathway; D010732:Phosphofructokinase-1 / Q000235:genetics / Q000378:metabolism; D014994:Xylose / Q000378:metabolism*
D029968:Escherichia coli Proteins; D014994:Xylose; D001089:Arabinose; D005954:Glucosephosphate Dehydrogenase; D010732:Phosphofructokinase-1; D005947:Glucose; D008358:Mannose