Identification of European isolates of the lager yeast parent Saccharomyces eubayanus

Abstract

Lager brewing first occurred in Bavaria in the 15th century, associated with restrictions of brewing to colder months. The lager yeast, Saccharomyces pastorianus, is cold tolerant. It is a hybrid between Saccharomyces cerevisiae and Saccharomyces eubayanus, and has been found only in industrial settings. Natural isolates of S. eubayanus were first discovered in Patagonia 11 years ago. They have since been isolated from China, Tibet, New Zealand, and North America, but not from Europe. Here, we describe the first European strains UCD646 and UCD650, isolated from a wooded area on a university campus in Dublin, Ireland. We generated complete chromosome level assemblies of both genomes using long- and short-read sequencing. The UCD isolates belong to the Holarctic clade. Genome analysis shows that isolates similar to the Irish strains contributed to the S. eubayanus component of S. pastorianus, but isolates from Tibet made a larger contribution.

A widespread inversion polymorphism conserved among Saccharomyces species is caused by recurrent homogenization of a sporulation gene family

“…eubayanus from Irish soil samples [ 21 ] and sequenced their genomes using Oxford Nanopore MinION long reads followed by short-read error correction. One of these isolates is REF and the other is INV (UCD646 and UCD650, respectively; Fig 2A ), even though the two isolates differ by only 2,517 homozygous SNPs and came from soil samples located only 17 meters apart [ 21 ]. Long-read assemblies are available for only a few strains of other Saccharomyces species, but the type strain of S .…”

A new hypothesis for the origin of the lager yeast Saccharomyces pastorianus

“…Current opinion (quite simplified) is that a rare S. eubayanus was accidentally introduced to an existing S. cerevisiae habitat, the two interacted and formed a new species, S. pastorianus (Gallone et al 2017a , Sampaio et al 2017 ). Libkind et al ( 2011 ) reported the isolation of S. eubayanus in South America in 2011, and the yeast was subsequently found in Argentina, Chile, Tibet, China, New Zealand, USA, and most recently in Ireland (Libkind et al 2011 , Bing et al 2014 , Peris et al 2014 , Gayevskiy and Goddard 2016 , Eizaguirre et al 2018 , Nespolo et al 2020 ; Bergin et al 2022 ). Relatively few isolates of S. eubayanus that are not associated to Nothofagus sp.…”

“…On the other hand, the recent discovery of wild S. eubayanus in Ireland (suggests that there were, and still are, European populations of this yeast and supports the idea of European ancestry for S. pastorianus (Sampaio 2022 ). The Irish isolates belong to the same Holarctic clade as those from Tibet and genome analysis shows contributions from both populations to the S. eubayanus component of S. pastorianus (Bergin et al 2022 ).…”

Presence of Saccharomyces eubayanus in fermentative environments reveals a new adaptive scenario in Patagonia

“…This species was initially found in association with trees of the genus Nothofagus in Patagonia (Argentina) (Libkind et al, 2011) and subsequently found in other trees in Patagonia (Eizaguirre et al, 2018; Langdon et al, 2020; Nespolo et al, 2020; Origone et al, 2014). It is also distributed in Asia (Bing et al, 2014), North America (Eizaguirre et al, 2018; Langdon et al, 2020; Peris et al, 2016, 2023) and has recently been isolated from Europe (Bergin et al, 2022). This cold‐tolerant yeast is represented in Patagonia by two major populations (A/PA population and B/PB population) divided into five subpopulations (PA‐1, PA‐2, PB‐1, PB‐2, and PB‐3) (Eizaguirre et al, 2018; Peris et al, 2014, 2016).…”