Efficient yeast breeding using a sake metabolome analysis for a strain evaluation

Breeding sake yeast typically involves generating several gene mutants through UV irradiation or mutagen treatment and selecting those with desired traits based on indicators such as analog resistance. However, this approach often alters traits beyond the target trait due to the random and numerous mutations introduced. To address this issue, we used a previously established metabolome analysis, a sake metabolome analysis, to evaluate the selected yeast strain. After screening for target traits, 110 sake yeast candidates were cultured in yeastnitrogen-based liquid medium using test tubes. The contents were extracted and subjected to comprehensive metabolite analysis through sake metabolome analysis. A phylogenetic tree was then constructed using the metabolome analysis data, enabling the selection of candidate yeasts with only the target traits modified and other traits similar to the parental strain. Selected 21 candidate strains underwent fermentation tests, and the resulting sakes were analyzed using liquid chromatography quadrupole/time-of-flight mass spectrometry (LC-Q/TOF-MS). The findings suggested that the metabolomic data of yeast extracts obtained by simple small-scale culture was similar to the data of resulting sake in the larger-scale fermentation tests. This underscores the utility of metabolome analysis data of yeast extracts in the yeast breeding process, marking the first report proposing the use of the sake metabolome analysis method for yeast breeding.