The construction and application of diploid sake yeast with a homozygous mutation in the FAS2 gene

J Biosci Bioeng. 2010 Dec;110(6):675-8. doi: 10.1016/j.jbiosc.2010.07.007. Epub 2010 Aug 12.


In Japanese sake brewing, cerulenin-resistant sake yeasts produce elevated levels of ethyl caproate, an important flavor component. The FAS2 mutation FAS2-1250S of Saccharomyces cerevisiae generates a cerulenin-resistant phenotype. This mutation is dominant, and, in general, cerulenin-resistant diploid sake yeast strains carry this mutation heterozygously. Here we constructed diploid sake yeast with a homozygous mutation of FAS2 using the high-efficiency loss of heterozygosity method. The homozygous mutants grew more slowly in YPD medium than did the wild-type and heterozygous mutants, and they produced more ethyl caproate during sake brewing. In addition, although both the wild-type and heterozygous mutant were sensitive to 4 mg/l cerulenin, the homozygous mutant was resistant to more than 4 mg/l cerulenin. Next, we obtained a homozygous mutant of FAS2 without inducing genetic modification. After cultivating the heterozygous FAS2 mutant K-1801 in YPD, homozygous mutants were selected on medium containing high concentrations of cerulenin. Non-genetically modified yeast with a homozygous mutation of FAS2 produced 2.2-fold more ethyl caproate than did heterozygous yeast. Moreover, high-quality Japanese sake with a very rich flavor could be brewed using yeast containing a homozygous mutation in the FAS2 gene.

MeSH terms

  • Alcoholic Beverages*
  • Caproates / metabolism*
  • Cerulenin / pharmacology
  • Diploidy
  • Genes, Fungal
  • Homozygote
  • Mutation
  • Saccharomyces cerevisiae / genetics*
  • Saccharomyces cerevisiae / growth & development
  • Saccharomyces cerevisiae / metabolism


  • Caproates
  • Cerulenin
  • ethyl hexanoate