Saccharomyces cerevisiae Kyokai no.7 (= NBRC 101557)

日本語で表示

Sake is a traditional Japanese alcoholic beverage that is fermented from steamed rice by the concerted actions of filamentous fungi, such as Aspergillus oryzae, and yeast. Yeast cells produce ethanol, higher alcohols and their esters, organic acids and amino acids in sake brewing process. Hence, the choice of a yeast strain is one of the key brewing processes determining aroma and taste of sake products. Sake yeast strains are known to possess characteristics ideal for sake brewing, such as high ethanol productivity, good growth and fermentation at low temperature and aroma production.

Saccharomyces cerevisiae Kyokai No.7 (K7) was first isolated in 1946 from a sake brewery in Nagano Prefecture, Japan. K7 has been one of the most extensively used sake yeast strains during the past several decades. K7 also has been employed in numerous genetic and biochemical studies as a model sake yeast and as a parent strain for breeding. The 11.87 megabase (Mb) genome of K7 is composed of 16 chromosomes and mitochondrial DNA, and contains 6,209 genes. Although the entire assembled sequence and structure of the K7 genome were nearly identical to those of the standard laboratory strain S288C genome, subtelomeric polymorphisms and inverted regions were identified. Since K7 is a heterozygous diploid, a survey of heterozygous base positions identified 1,347 different nucleotides between two homologous chromosomes. These findings have provided the basis for future studies on genealogy and evolution of sake yeast, and may be clues for finding relationships among genotypes and phenotypes for good sake brewing.

photo by National Research Institute of Brewing