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Deletion of JEN1 and ADY2 reduces lactic acid yield from an engineered Saccharomyces cerevisiae, in xylose medium, expressing a heterologous lactate dehydrogenase.

Authors
  • Turner, Timothy L1
  • Lane, Stephan1, 2
  • Jayakody, Lahiru N1
  • Zhang, Guo-Chang1
  • Kim, Heejin1, 2
  • Cho, Whiyeon1
  • Jin, Yong-Su1, 2
  • 1 Department of Food Science and Human Nutrition, 260 Bevier Hall, 905 South Goodwin Avenue, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
  • 2 Carl R. Woese Institute for Genomic Biology, 1206 West Gregory Avenue, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
Type
Published Article
Journal
FEMS Yeast Research
Publisher
Oxford University Press
Publication Date
Sep 01, 2019
Volume
19
Issue
6
Identifiers
DOI: 10.1093/femsyr/foz050
PMID: 31505595
Source
Medline
Keywords
Language
English
License
Unknown

Abstract

Microorganisms have evolved to produce specific end products for many reasons, including maintaining redox balance between NAD+ and NADH. The yeast Saccharomyces cerevisiae, for example, produces ethanol as a primary end product from glucose for the regeneration of NAD+. Engineered S. cerevisiae strains have been developed to ferment lignocellulosic sugars, such as xylose, to produce lactic acid by expression of a heterologous lactate dehydrogenase (ldhA from Rhizopus oryzae) without genetic perturbation to the native ethanol pathway. Surprisingly, the engineered yeast strains predominantly produce ethanol from glucose, but produce lactic acid as the major product from xylose. Here, we provide initial evidence that the shift in product formation from ethanol to lactic acid during xylose fermentation is at least partially dependent on the presence of functioning monocarboxylate transporter genes/proteins, including JEN1 and ADY2, which are downregulated and unstable in the presence of glucose, but upregulated/stable on xylose. Future yeast metabolic engineering studies may find the feedstock/carbon selection, such as xylose, an important step toward improving the yield of target end products. © FEMS 2019.

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