Microbe domestication and the identification of the wild genetic stock of lager-brewing yeast

Abstract

Domestication of plants and animals promoted humanity's transition from nomadic to sedentary lifestyles, demographic expansion, and the emergence of civilizations. In contrast to the well-documented successes of crop and livestock breeding, processes of microbe domestication remain obscure, despite the importance of microbes to the production of food, beverages, and biofuels. Lager-beer, first brewed in the 15th century, employs an allotetraploid hybrid yeast, Saccharomyces pastorianus (syn. Saccharomyces carlsbergensis ), a domesticated species created by the fusion of a Saccharomyces cerevisiae ale-yeast with an unknown cryotolerant Saccharomyces species. We report the isolation of that species and designate it Saccharomyces eubayanus sp. nov. because of its resemblance to Saccharomyces bayanus (a complex hybrid of S. eubayanus , Saccharomyces uvarum , and S. cerevisiae found only in the brewing environment). Individuals from populations of S. eubayanus and its sister species, S. uvarum , exist in apparent sympatry in Nothofagus (Southern beech) forests in Patagonia, but are isolated genetically through intrinsic postzygotic barriers, and ecologically through host-preference. The draft genome sequence of S. eubayanus is 99.5% identical to the non- S. cerevisiae portion of the S. pastorianus genome sequence and suggests specific changes in sugar and sulfite metabolism that were crucial for domestication in the lager-brewing environment. This study shows that combining microbial ecology with comparative genomics facilitates the discovery and preservation of wild genetic stocks of domesticated microbes to trace their history, identify genetic changes, and suggest paths to further industrial improvement.

Local climatic adaptation in a widespread microorganism

“…This phenomenon could be another explanation for the shifted geographical distributions of S. cerevisiae and S. paradoxus [20], as it was previously shown that they have contrasted tolerance to freeze-thaw cycles [27]. Additional evidence for the prominent role of temperature on budding yeast distribution was found in Saccharomyces eubayanus, a cold-adapted yeast that has only been reported in Patagonian forests, where climate is comparable with that of northeastern North America [35]. rspb.royalsocietypublishing.org Proc.…”

Characterization of Technologically Utilized Saccharomyces Yeast

“…These results suggest that they are hybrid strains of S. cerevisiae and S. eubayanus. The hybrid origin of bottom brewing and wine yeast is often described in the literature (Bing et al, 2014, Libkind et al;Sipiczski, 2008 (Bing et al, 2014;Libkind et al, 2011;Sipiczski, 2008). U typového kmene S. pastorianus a S. pastorianus NCYC 396 došlo k amplifikaci pouze fragmentu o velikosti 228 bp, který je charakteristický pro S. eubayanus.…”

125th Anniversary Review: Yeast Flocculation and Sedimentation in Brewing

“…nov. 44 . Lager strains possess FLO genes derived from both their parents, and so have an even larger number and greater diversity of FLO genes in their genomes than ale (S. cerevisiae) strains.…”