Targeted Mutations Produce Divergent Characteristics in Pedigreed Sake Yeast Strains

Area of Science:

• Yeast genetics and brewing science
• Agricultural biotechnology
• Metabolic engineering

Background:

• Genetic background significantly influences trait characteristics in breeding crops, livestock, and microorganisms.
• Understanding how identical mutations affect traits across different genetic backgrounds is crucial for effective breeding.
• Previous work involved genome editing of sake yeast strain Kyokai No. 7 to enhance brewing characteristics.

Purpose of the Study:

• To investigate the impact of introducing specific targeted mutations (AWA1, CAR1, MDE1, FAS2) into diverse sake yeast genetic backgrounds.
• To determine if the same excellent brewing characteristics are consistently achieved across different pedigreed sake yeast strains.
• To analyze how genetic background influences the resulting sake components and yeast cell morphology post-genome editing.

Main Methods:

• Genome editing of four specific genes (AWA1, CAR1, MDE1, FAS2) in standard sake yeast (Kyokai No. 7).
• Introduction of the same targeted mutations into other pedigreed sake yeast strains (Kyokai No. 6, No. 9, No. 10).
• Analysis of sake components (e.g., amino acids, isobutanol) and yeast cell morphology in genome-edited strains.

Main Results:

• Sake yeasts with the same excellent brewing characteristics were successfully created across different genetic backgrounds.
• Significant variations were observed in other sake components, such as amino acid and isobutanol content, depending on the yeast strain background.
• Changes in yeast cell morphology induced by targeted mutations also varied across different strain backgrounds, with limited commonly altered parameters.

Conclusions:

• Targeted mutations can lead to divergent characteristics when introduced into different pedigreed sake yeast strains.
• The genetic background plays a critical role in modulating the phenotypic outcomes of genome editing.
• This study suggests a breeding strategy to generate a variety of sake yeasts with desirable brewing characteristics by leveraging strain-specific responses to mutations.