Novel brewing yeast hybrids: creation and application

Abstract

The natural interspecies Saccharomyces cerevisiae × Saccharomyces eubayanus hybrid yeast is responsible for global lager beer production and is one of the most important industrial microorganisms. Its success in the lager brewing environment is due to a combination of traits not commonly found in pure yeast species, principally low-temperature tolerance, and maltotriose utilization. Parental transgression is typical of hybrid organisms and has been exploited previously for, e.g., the production of wine yeast with beneficial properties. The parental strain S. eubayanus has only been discovered recently and newly created lager yeast strains have not yet been applied industrially. A number of reports attest to the feasibility of this approach and artificially created hybrids are likely to have a significant impact on the future of lager brewing. De novo S. cerevisiae × S. eubayanus hybrids outperform their parent strains in a number of respects, including, but not restricted to, fermentation rate, sugar utilization, stress tolerance, and aroma formation. Hybrid genome function and stability, as well as different techniques for generating hybrids and their relative merits are discussed. Hybridization not only offers the possibility of generating novel non-GM brewing yeast strains with unique properties, but is expected to aid in unraveling the complex evolutionary history of industrial lager yeast.

Conventional and Non-Conventional Yeasts in Beer Production

“…The lager yeast has been divided long time ago into two groups: (I) Saaz and (II) Frohberg [15]. S. pastorianus group I (Saaz) was produced by hybridization of S. cerevisiae (ale) with S. eubayanus, whereas S. pastorianus group II (Frohberg) was obtained by a further hybridization with a different S. cerevisiae strain used in stout production ( Figure 1).…”

Microbial acidification, alcoholization, and aroma production during spontaneous lambic beer production

“…Strains belonging to species of the Saccharomyces genus are most commonly used in the production of both lagers and ales . As the majority of beers produced are bottom‐fermented, most of the yeasts used for brewing are S. pastorianus strains, which are interspecific hybrids between the mesophilic species S. cerevisiae and the cryo‐tolerant species Saccharomyces eubayanus . Two major lineages of S. pastorianus , Saaz and Frohberg (sometimes referred to as S. carlsbergensis and S. pastorianus , respectively), with distinct genetic and fermentation characteristics, exist.…”

“…13 As the majority of beers produced are bottom-fermented, most of the yeasts used for brewing are S. pastorianus strains, which are interspecific hybrids between the mesophilic species S. cerevisiae and the cryo-tolerant species Saccharomyces eubayanus. 19,20 Two major lineages of S. pastorianus, Saaz and Frohberg (sometimes referred to as S. carlsbergensis and S. pastorianus, respectively), with distinct genetic and fermentation characteristics, exist. Although long thought to be the result of one hybridization event throughout evolution, genomic analysis suggests that the Saaz and Frohberg lineages were created by at least two distinct hybridization events between nearly identical strains of S. eubayanus and relatively more diverse strains of S. cerevisiae.…”

Saccharomyces and Non-Saccharomyces Starter Yeasts

“…Indeed, the natural interspecies S. pastorianus (i.e., S. cerevisiae × S. eubayanus) hybrid yeast is responsible for global lager beer production and is one of the most important industrial microorganisms [30]. Its success in the lager-brewing environment is due to a combination of traits that are not commonly found in S. cerevisiae yeast, as mainly the low temperature tolerance and maltotriose use.…”