Applied Microbiology and Biotechnology

, Volume 98, Issue 3, pp 1087–1094

Analysis of cellodextrin transporters from Neurospora crassa in Saccharomyces cerevisiae for cellobiose fermentation

  • Heejin Kim
  • Won-Heong Lee
  • Jonathan M. Galazka
  • Jamie H. D. Cate
  • Yong-Su Jin
Biotechnological products and process engineering

DOI: 10.1007/s00253-013-5339-2

Cite this article as:
Kim, H., Lee, WH., Galazka, J.M. et al. Appl Microbiol Biotechnol (2014) 98: 1087. doi:10.1007/s00253-013-5339-2

Abstract

Saccharomyces cerevisiae can be engineered to ferment cellodextrins produced by cellulases as a product of cellulose hydrolysis. Direct fermentation of cellodextrins instead of glucose is advantageous because glucose inhibits cellulase activity and represses the fermentation of non-glucose sugars present in cellulosic hydrolyzates. To facilitate cellodextrin utilization by S. cerevisiae, a fungal cellodextrin-utilizing pathway from Neurospora crassa consisting of a cellodextrin transporter and a cellodextrin hydrolase has been introduced into S. cerevisiae. Two cellodextrin transporters (CDT-1 and CDT-2) were previously identified in N. crassa, but their kinetic properties and efficiency for cellobiose fermentation have not been studied in detail. In this study, CDT-1 and CDT-2, which are hypothesized to transport cellodextrin with distinct mechanisms, were introduced into S. cerevisiae along with an intracellular β-glucosidase (GH1-1). Cellobiose transport assays with the resulting strains indicated that CDT-1 is a proton symporter while CDT-2 is a simple facilitator. A strain expressing CDT-1 and GH1-1 (DCDT-1G) showed faster cellobiose fermentation than the strain expressing CDT-2 and GH1-1 (DCDT-2G) under various culture conditions with different medium compositions and aeration levels. While CDT-2 is expected to have energetic benefits, the expression levels and kinetic properties of CDT-1 in S. cerevisiae appears to be optimum for cellobiose fermentation. These results suggest CDT-1 is a more effective cellobiose transporter than CDT-2 for engineering S. cerevisiae to ferment cellobiose.

Keywords

Cellulosic ethanolCellodextrin transportersIntracellular β-glucosidaseEngineered S. cerevisiae

Copyright information

© Springer-Verlag Berlin Heidelberg 2013

Authors and Affiliations

  • Heejin Kim
    • 1
    • 2
  • Won-Heong Lee
    • 1
    • 2
  • Jonathan M. Galazka
    • 3
    • 4
  • Jamie H. D. Cate
    • 3
    • 4
  • Yong-Su Jin
    • 1
    • 2
  1. 1.Department of Food Science and Human NutritionUniversity of Illinois at Urbana-ChampaignUrbanaUSA
  2. 2.Institute for Genomic BiologyUniversity of Illinois at Urbana-ChampaignUrbanaUSA
  3. 3.Department of Molecular and Cell BiologyUniversity of California at BerkeleyBerkeleyUSA
  4. 4.Physical Biosciences DivisionLawrence Berkeley National LaboratoryBerkeleyUSA