Episode 130: Yeast Genome Changes During Serial Repitching
Oct 30, 2023
auto_awesome
Maitreya Dunham and Tom Schmidlin discuss an exciting study on yeast mutations during serial repitching. They explore the implications of serial re-pitching in yeast, understanding mutants in yeast genome changes, studying the evolution of Chico yeast strains, and methods of tracking mutations in yeast genomes.
Yeast cells undergo various genome changes during cereal re-pitching, impacting metabolite production, growth, and stress tolerance.
Brewing strains have unique and complex genomes, and understanding their genetic makeup is crucial for beer quality and characteristics.
Deep dives
Researching Yeast Mutations in Serial Re-pitching
A study conducted at the University of Washington focused on the evolution of yeast during cereal re-pitching. The research aimed to understand how mutations occur and how they can affect the traits of yeast cells. The study found that during the re-pitching process, yeast cells underwent various genome changes, including gaining an extra chromosome or rearranging their chromosomes. These changes can have profound consequences for yeast metabolism, affecting metabolite production, growth, and stress tolerance. The researchers also explored potential differences in traits like flocculation, cold tolerance, and ethanol resistance. The study highlighted the value of studying yeast evolution and its implications for industrial applications, health, and the brewing industry in particular.
Genetic Investigation of Brewing Strains
Brewing strains, like Chico yeast, have unique and complex genomes with multiple copies of chromosomes and chromosome fragments. These genetic variations contribute to the specific traits found in brewing strains. The researchers performed genome sequencing on different brewing strains, including those from yeast suppliers. They discovered variations between strains, such as extra copies of certain chromosomes and rearranged chromosome segments. The genomic differences among brewing strains could influence the flavor and brewing characteristics of beers. The study emphasized the importance of understanding the genetic makeup of brewing strains and their impact on brewing outcomes and product quality.
Observations on Mutations in Serial Repitches
The researchers conducted a series of cereal re-pitching experiments using the Chico yeast strain, taking samples at various time points to observe the occurrence of mutations. One notable finding was that by around 10 to 15 re-pitches, mutations began to have a noticeable presence in the yeast population, with the mutants comprising about 40% of the population by the end of the re-pitching process. These mutations included gaining an extra chromosome or rearranging existing chromosomes. The researchers also tested the isolated mutant strains in lab conditions and found differences in traits such as growth rate and ethanol resistance compared to the original strain. These observations highlighted the importance of monitoring and understanding the mutations that arise during cereal re-pitching.
Potential Applications and Future Research
The study explored the potential benefits and challenges associated with yeast evolution during cereal re-pitching. The mutant strains isolated during the research showed differences in beer sensory attributes, such as esters, sweetness, and hop characteristics, suggesting their potential influence on flavor profiles. Understanding how mutations affect yeast physiology and beer production could lead to the development of new brewing strains with desirable traits. The researchers acknowledged the value of further collaborations with breweries to gather additional samples and investigate the genetic evolution of strains in different brewing environments. Future research may involve using advanced techniques like CRISPR to engineer specific mutations and evaluate their impact on beer quality and brewing performance.
