Applied Biochemistry and Biotechnology

, Volume 98, Issue 1–9, pp 341–355

Characterization of heterologous and native enzyme activity profiles in metabolically engineered Zymomonas mobilis strains during batch fermentation of glucose and xylose mixtures

  • Qiang Gao
  • Min Zhang
  • James D. McMillan
  • Dhinakar S. Kompala


Zymomonas mobilis has been metabolically engineered to broaden its substrate utilization range to include d-xylose and l-arabinose. Both genomically integrated and plasmid-bearing Z. mobilis strains that are capable of fermenting the pentose d-xylose have been created by incorporating four genes: two genes encoding xylose utilization metabolic enzymes (xylA/xylB) and two genes encoding pentose phosphate pathway enzymes (talB/tktA). We have characterized the activities of the four newly introduced enzymes for xylose metabolism, along with those of three native glycolytic enzymes, in two different xylose-fermenting Z. mobilis strains. These strains were grown on glucose-xylose mixtures in computer-controlled fermentors. Samples were collected and analyzed to determine extracellular metabolite concentrations as well as the activities of several intracellular enzymes in the xylose and glucose uptake and catabolism pathways. These measurements provide new insights on the possible bottlenecks in the engineered metabolic pathways and suggest methods for further improving the efficiency of xylose fermentation.

Index Entries

Recombinant Zymomonas mobilis xylose fermentation enzyme analysis ethanol byproducts 


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Copyright information

© Humana Press Inc. 2002

Authors and Affiliations

  • Qiang Gao
    • 1
  • Min Zhang
    • 2
  • James D. McMillan
    • 2
  • Dhinakar S. Kompala
    • 1
  1. 1.Department of Chemical EngineeringUniversity of ColoradoBoulder
  2. 2.Biotechnology Division for Fuels and ChemicalsNational Renewable Energy LaboratoryGolden

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