Identification of sporulation deficiency-related genes in sake yeast and establishment of yeast breeding method by crossing

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K05788
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 38020:Applied microbiology-related
• Research Institution: Kagoshima University
• Principal Investigator: TAMAKI Hisanori 鹿児島大学, 農水産獣医学域農学系, 教授 (20212045)
• Co-Investigator(Kenkyū-buntansha): 赤尾 健 独立行政法人酒類総合研究所, 研究部門, 部門長 (50416426) ; 二神 泰基 鹿児島大学, 農水産獣医学域農学系, 准教授 (60512027)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 清酒酵母 / 焼酎酵母 / 交配 / 比較ゲノム / 胞子形成不全 / 胞子発芽不全

Outline of Final Research Achievements

The 10 a-mating type and 5 α-mating type haploid K7 sake yeast strains were selected as superior strains based on their growth and fermentation performance. In addition, each a- and α- mating type haploid K2 shochu yeast strain (HO gene disrupted strain) was also selected as a superior strain. Diploid strains with high mating frequency were obtained by crossing K7 and K2 strains with opposite mating type. These diploid strains were allowed to sporulate, and the strains with high sporulation frequency was isolated. Genomic DNA was extracted from the strains as well as their parental strains and subjected for sequence analysis and comparative genomics. The germination rate of spores from the isolated strains was measured and found to be intermediate between that of shochu yeast (100% germination rate) and sake yeast (about 0% germination rate).

Free Research Field

醸造微生物学

Academic Significance and Societal Importance of the Research Achievements

清酒酵母K7株は、低温での高い発酵能によって選ばれてきたが、胞子形成能が低く、またできた胞子の発芽率も低いことから、交配による育種は困難である。それに対して、焼酎酵母は、清酒酵母と近縁でありながら胞子形成率、胞子発芽率ともに高いことから、これらの株を交配させ、胞子形成能、胞子発芽能が回復した株を取得し、親株との比較ゲノムを行うことで、清酒酵母の胞子形成不全や胞子発芽不全の原因遺伝子を特定することは、酵母における胞子形成、胞子発芽における新たな遺伝子の機能解明につながるとともに、清酒産業において交配による優良酵母の育種を可能にするものである。