Expression of a xylose-specific transporter improves ethanol production by metabolically engineered Zymomonas mobilis

Kori L. Dunn, Christopher V. Rao

Research output: Contribution to journalArticlepeer-review

Abstract

Zymomonas mobilis is a promising organism for biofuel production as it can produce ethanol from glucose at high rates. However, Z. mobilis does not natively ferment C5 sugars such as xylose. While it has been engineered to do so, the engineered strains do not metabolize these sugars at high rates. Previous research has identified some of the bottlenecks associated with xylose metabolism in Z. mobilis. In this work, we investigated transport as a possible bottleneck. In particular, we hypothesized that the slow uptake of xylose through the promiscuous Glf transporter may limit the efficiency of xylose metabolism in Z. mobilis. To test this hypothesis, we expressed XylE, the low-affinity xylose transporter from Escherichia coli, in a xylose-utilizing strain of Z. mobilis. Our results show that the expression of this pentose-specific transporter improves the rate of xylose utilization in Z. mobilis; however, this enhancement is seen only at high xylose concentrations. In addition, we also found that overexpression of the promiscuous Z. mobilis transporter Glf yielded similar results, suggesting that the transport bottleneck is not due to the specificity, but rather the capacity for sugar uptake.

Original languageEnglish (US)
Pages (from-to)6897-6905
Number of pages9
JournalApplied Microbiology and Biotechnology
Volume98
Issue number15
DOIs
StatePublished - Aug 2014

Keywords

  • Ethanol
  • Fermentation
  • Sugar transport
  • Xylose
  • Zymomonas mobilis

ASJC Scopus subject areas

  • Biotechnology
  • Applied Microbiology and Biotechnology

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