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Isolation of a high malic and low acetic acid-producing sake yeastSaccharomyces cerevisiaestrain screened from respiratory inhibitor 2,4-dinitrophenol (DNP)-resistant strains

Authors
Journal
Journal of Bioscience and Bioengineering
1389-1723
Publisher
Elsevier
Volume
117
Issue
1
Identifiers
DOI: 10.1016/j.jbiosc.2013.06.016
Keywords
  • Sake Yeast
  • Organic Acids
  • Mitochondria
  • Respiration Inhibitor
  • Redox Balance
Disciplines
  • Biology

Abstract

We isolated 2,4-dinitrophenol (DNP)-resistant sake yeast strains by UV mutagenesis. Among the DNP-resistant mutants, we focused on strains exhibiting high malic acid and low acetic acid production. The improved organic acid composition is unlikely to be under the control of enzyme activities related to malic and acetic acid synthesis pathways. Instead, low mitochondrial activity was observed in DNP-resistant mutants, indicating that the excess pyruvic acid generated during glycolysis is not metabolized in the mitochondria but converted to malic acid in the cytosol. In addition, the NADH/NAD+ ratio of the DNP-resistant strains was higher than that of the parental strain K901. These results suggest that the increased NADH/NAD+ ratio together with the low mitochondrial activity alter the organic acid composition because malic acid synthesis requires NADH, while acetic acid uses NAD+.

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