scholarly journals Lager yeast design through meiotic segregation of a fertile Saccharomyces cerevisiae x Saccharomyces eubayanus hybrid

2021 ◽  
Author(s):  
Kristoffer Krogerus ◽  
Frederico Magalhaes ◽  
Sandra Castillo ◽  
Gopal Peddinti ◽  
Virve Vidgren ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Phenotypic Diversity ◽  
Single Cells ◽  
Fermentation Performance ◽  
Hybrid Strain ◽  
Lager Yeast ◽  
Brewing Yeast ◽  
Acetate Ester ◽  
Copy Numbers ◽  
Saccharomyces Eubayanus

Yeasts in the lager brewing group are closely related and consequently do not exhibit significant genetic variability. Here, an artificial Saccharomyces cerevisiae x Saccharomyces eubayanus tetraploid interspecies hybrid was created by rare mating, and its ability to sporulate and produce viable gametes was exploited to generate phenotypic diversity. Four spore clones obtained from a single ascus were isolated, and their brewing-relevant phenotypes were assessed. These F1 spore clones were found to differ with respect to fermentation performance under lager brewing conditions (15 C, 15 Plato), production of volatile aroma compounds, flocculation potential and temperature tolerance. One spore clone, selected for its rapid fermentation and acetate ester production was sporulated to produce an F2 generation, again comprised of four spore clones from a single ascus. Again, phenotypic diversity was introduced. In two of these F2 clones, the fermentation performance was maintained and acetate ester production was improved relative to the F1 parent and the original hybrid strain. Strains also performed well in comparison to a commercial lager yeast strain. Spore clones varied in ploidy and chromosome copy numbers, and faster wort fermentation was observed in strains with a higher ploidy. An F2 spore clone was also subjected to 10 consecutive wort fermentations, and single cells were isolated from the resulting yeast slurry. These isolates also exhibited variable fermentation performance and chromosome copy numbers, highlighting the instability of polyploid interspecific hybrids. These results demonstrate the value of this natural approach to increase the phenotypic diversity of lager brewing yeast strains.

scholarly journals Lager Yeast Design Through Meiotic Segregation of a Saccharomyces cerevisiae × Saccharomyces eubayanus Hybrid

2021 ◽  
Vol 2 ◽  
Author(s):  
Kristoffer Krogerus ◽  
Frederico Magalhães ◽  
Sandra Castillo ◽  
Gopal Peddinti ◽  
Virve Vidgren ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Phenotypic Diversity ◽  
Single Cells ◽  
Fermentation Performance ◽  
Hybrid Strain ◽  
Lager Yeast ◽  
Brewing Yeast ◽  
Acetate Ester ◽  
Copy Numbers ◽  
Saccharomyces Eubayanus

Yeasts in the lager brewing group are closely related and consequently do not exhibit significant genetic variability. Here, an artificial Saccharomyces cerevisiae × Saccharomyces eubayanus tetraploid interspecies hybrid was created by rare mating, and its ability to sporulate and produce viable gametes was exploited to generate phenotypic diversity. Four spore clones obtained from a single ascus were isolated, and their brewing-relevant phenotypes were assessed. These F1 spore clones were found to differ with respect to fermentation performance under lager brewing conditions (15°C, 15 °Plato), production of volatile aroma compounds, flocculation potential and temperature tolerance. One spore clone, selected for its rapid fermentation and acetate ester production was sporulated to produce an F2 generation, again comprised of four spore clones from a single ascus. Again, phenotypic diversity was introduced. In two of these F2 clones, the fermentation performance was maintained and acetate ester production was improved relative to the F1 parent and the original hybrid strain. Strains also performed well in comparison to a commercial lager yeast strain. Spore clones varied in ploidy and chromosome copy numbers, and faster wort fermentation was observed in strains with a higher ploidy. An F2 spore clone was also subjected to 10 consecutive wort fermentations, and single cells were isolated from the resulting yeast slurry. These isolates also exhibited variable fermentation performance and chromosome copy numbers, highlighting the instability of polyploid interspecific hybrids. These results demonstrate the value of this natural approach to increase the phenotypic diversity of lager brewing yeast strains.

scholarly journals Hybridization of Saccharomyces cerevisiae Sourdough Strains with Cryotolerant Saccharomyces bayanus NBRC1948 as a Strategy to Increase Diversity of Strains Available for Lager Beer Fermentation

2020 ◽  
Author(s):  
Martina Catallo ◽  
Fabrizio Iattici ◽  
Cinzia Randazzo ◽  
Cinzia Caggia ◽  
Kristoffer Krogerus ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
De Novo ◽  
Yeast Culture ◽  
Culture Collections ◽  
Lager Yeast ◽  
Ethyl Hexanoate ◽  
Brewing Yeast ◽  
Saccharomyces Bayanus ◽  
Lager Beer ◽  
Saccharomyces Eubayanus

The search for novel brewing strains from non-brewing environments represents an emerging trend to increase genetic and phenotypic diversities in brewing yeast culture collections. Another valuable tool is hybridization, where beneficial traits of individual strains are combined in a single organism. This has been used successfully to create de novo hybrids from parental brewing strains by mimicking natural Saccharomyces cerevisiae ale x Saccharomyces eubayanus lager yeast hybrids. Here, we integrated both these approaches to create synthetic hybrids for lager fermentation using parental strains from niches other than beer. Using a phenotype-centered strategy, S. cerevisiae sourdough strains and the S. eubayanus x Saccharomyces uvarum strain NBRC1948 (also referred to as Saccharomyces bayanus) were chosen for their brewing aptitudes. We demonstrated that, in contrast to S. cerevisiae x S. uvarum crosses, hybridization yield was positively affected by time of exposure to starvation, but not by staggered mating. In laboratory-scale fermentation trials at 20°C, one triple S. cerevisiae x S. eubayanus x S. uvarum hybrid showed a heterotic phenotype compared with the parents. In 2L wort fermentation trials at 12°C, this hybrid inherited the ability to consume efficiently maltotriose from NBRC1948 and, like the sourdough S. cerevisiae parent, produced appreciable levels of the positive aroma compounds 3-methylbutyl acetate (banana/pear), ethyl acetate (general fruit aroma) and ethyl hexanoate (green apple, aniseed, and cherry aroma). Based on these evidences, the phenotype-centered approach appears promising for design of de novo lager beer hybrids and may help to diversify aroma profiles in lager beers.

A study of changes in flocculence in a single cell culture of a strain of Saccharomyces cerevisiae

1963 ◽  
Vol 157 (967) ◽  
pp. 223-233 ◽  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Culture ◽  
Liquid Medium ◽  
Single Cell ◽  
Cell Cultures ◽  
Single Cells ◽  
Selective Advantage ◽  
Brewing Yeast ◽  
Flocculent Yeast ◽  
Single Cell Culture

A culture from a single cell of a flocculent brewing yeast became less flocculent during sub-culture on agar slopes. It was found that the culture had become a mixture of a number of variants differing in degree of flocculence. Five of the variants were studied using a sedi­-mentation method to measure flocculence. During subculture on agar and in liquid medium, single cell cultures of all these variants except the least flocculent gave rise to other variants. The proportion of less flocculent yeast increased during further subculture. The change was faster in liquid medium than on agar slopes. Yeast with more stable flocculence could be selected from the part of the population which did not change. Experiments with mixtures of ‘stable’ yeast indicated that the less flocculent yeast had a selective advantage, and that the mechanism of the selection involves the different physical properties of the yeast. All variants examined had the same rate of growth. Cultures derived from single cells of a given variant tended to give rise to the same new variants. Yeast with flocculence similar to the original strains could be isolated from the variant strains. It was not possible to determine whether these variants were produced by gene mutation since spore formation has never been detected in this yeast.

scholarly journals The impact of commercially available ale and lager yeast strains on the fermentative diversity of beers

2020 ◽  
Author(s):  
Diego Bonatto
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Lager Yeast ◽  
Brewing Yeast ◽  
Beer Fermentation ◽  
Yeast Strains ◽  
Saccharomyces Pastorianus ◽  
Commercial Yeast ◽  
Main Component ◽  
The Impact ◽  
Attenuation Profile

AbstractYeasts from the species Saccharomyces cerevisiae (ale yeast) and Saccharomyces pastorianus (lager yeast) are the main component of beer fermentation. It is known that different beer categories depend on the use of specific ale or lager strains, where the yeast imprint its distinctive fermentative profile to the beer. Despite this, there are no studies reporting how diverse, rich, and homogeneous the beer categories are in terms of commercially available brewing yeast strains. In this work, the diversity, richness, and evenness of different beer categories and commercial yeast strains available for brewing were evaluated by applying quantitative concepts of ecology analysis in a sample of 121,528 beer recipes. For this purpose, the frequency of ale or lager and dry or liquid yeast formulations usage was accessed and its influence in the fermentation temperature, attenuation profile, and number of recipes for a beer category were analyzed. The results indicated that many beer categories are preferentially fermented with dry yeast strains formulations instead of liquid yeasts, despite considering the high number of available liquid yeast formulations. Moreover, ale dry strains are preferentially used for lager brewing. The preferential use of specific yeast formulations drives the diversity, richness, and evenness of a beer category, showing that many yeast strains are potentially and industrially underexplored.

Breeding of lager yeast with Saccharomyces cerevisiae improves stress resistance and fermentation performance

Yeast ◽  
2012 ◽  
Vol 29 (8) ◽  
pp. 343-355 ◽  
Author(s):  
Rosa Garcia Sanchez ◽  
Natalia Solodovnikova ◽  
Jürgen Wendland
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Stress Resistance ◽  
Fermentation Performance ◽  
Lager Yeast

scholarly journals Enhanced Wort Fermentation with De Novo Lager Hybrids Adapted to High-Ethanol Environments

2017 ◽  
Vol 84 (4) ◽  
Author(s):  
Kristoffer Krogerus ◽  
Sami Holmström ◽  
Brian Gibson
Keyword(s):  
Adaptive Evolution ◽  
Ethanol Tolerance ◽  
De Novo ◽  
Fermentation Performance ◽  
Lager Yeast ◽  
Brewing Yeast ◽  
Ploidy Levels ◽  
Ester Formation ◽  
Lager Beer ◽  
High Ethanol

ABSTRACT Interspecific hybridization is a valuable tool for developing and improving brewing yeast in a number of industry-relevant aspects. However, the genomes of newly formed hybrids can be unstable. Here, we exploited this trait by adapting four brewing yeast strains, three of which were de novo interspecific lager hybrids with different ploidy levels, to high ethanol concentrations in an attempt to generate variant strains with improved fermentation performance in high-gravity wort. Through a batch fermentation-based adaptation process and selection based on a two-step screening process, we obtained eight variant strains which we compared to the wild-type strains in 2-liter-scale wort fermentations replicating industrial conditions. The results revealed that the adapted variants outperformed the strains from which they were derived, and the majority also possessed several desirable brewing-relevant traits, such as increased ester formation and ethanol tolerance, as well as decreased diacetyl formation. The variants obtained from the polyploid hybrids appeared to show greater improvements in fermentation performance than those derived from diploid strains. Interestingly, it was not only the hybrid strains, but also the Saccharomyces cerevisiae parent strain, that appeared to adapt and showed considerable changes in genome size. Genome sequencing and ploidy analysis revealed that changes had occurred at both the chromosome and single nucleotide levels in all variants. Our study demonstrates the possibility of improving de novo lager yeast hybrids through adaptive evolution by generating stable and superior variants that possess traits relevant to industrial lager beer fermentation. IMPORTANCE Recent studies have shown that hybridization is a valuable tool for creating new and diverse strains of lager yeast. Adaptive evolution is another strain development tool that can be applied in order to improve upon desirable traits. Here, we apply adaptive evolution to newly created lager yeast hybrids by subjecting them to environments containing high ethanol levels. We isolated and characterized a number of adapted variants which possess improved fermentation properties and ethanol tolerance. Genome analysis revealed substantial changes in the variants compared to the original strains. These improved variant strains were produced without any genetic modification and are suitable for industrial lager beer fermentations.

scholarly journals Enhanced wort fermentation with de novo lager hybrids adapted to high ethanol environments

2017 ◽  
Author(s):  
Kristoffer Krogerus ◽  
Sami Holmström ◽  
Brian Gibson
Keyword(s):  
Adaptive Evolution ◽  
Ethanol Tolerance ◽  
De Novo ◽  
Fermentation Performance ◽  
Lager Yeast ◽  
Brewing Yeast ◽  
Ploidy Levels ◽  
Ester Formation ◽  
Lager Beer ◽  
High Ethanol

AbstractInterspecific hybridization is a valuable tool for developing and improving brewing yeast in a number of industry-relevant aspects. However, the genomes of newly formed hybrids can be unstable. Here, we exploited this trait by adapting four brewing yeast strains, three of which were de novo interspecific lager hybrids with different ploidy levels, to high ethanol concentrations in an attempt to generate variant strains with improved fermentation performance in high-gravity wort. Through a batch fermentation-based adaptation process and selection based on a two-step screening process, we obtained eight variant strains which we compared to the wild-type strains in 2L-scale wort fermentations replicating industrial conditions. The results revealed that the adapted variants outperformed the strains from which they were derived, and the majority also possessed several desirable brewing-relevant traits, such as increased ester formation and ethanol tolerance, as well as decreased diacetyl formation. The variants obtained from the polyploid hybrids appeared to show greater improvements in fermentation performance. Interestingly, it was not only the hybrid strains, but also the S. cerevisiae parent strain, that appeared to adapt and showed considerable changes in genome size. Genome sequencing and ploidy analysis revealed that changes had occurred both at chromosome and single nucleotide level in all variants. Our study demonstrates the possibility of improving de novo lager yeast hybrids through adaptive evolution by generating stable and superior variants that possess traits relevant to industrial lager beer fermentation.ImportanceRecent studies have shown that hybridization is a valuable tool for creating new and diverse strains of lager yeast. Adaptive evolution is another strain development tool that can be applied in order to improve upon desirable traits. Here we apply adaptive evolution to newly created lager yeast hybrids by subjecting them to environments containing high ethanol levels. We isolate and characterize a number of adapted variants, which possess improved fermentation properties and ethanol tolerance. Genome analysis revealed substantial changes in the variants compared to the original strains. These improved variants strains were produced without any genetic modification, and are suitable for industrial lager beer fermentations.

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