Biology subjects

van der Merwe, G.

Publications and source records attributed to van der Merwe, G..

3 recordsLinked to original sources

bioRxiv2024

European Farmhouse Brewing Yeasts Form a Distinct Genetic Group

The brewing industry is constantly evolving, driven by the quest for novel flavors and fermentation characteristics that cater to evolving consumer preferences. This study explores the genetic and phenotypic diversity of European farmhouse yeasts, traditionally used in rural brewing practices and maintained outside of pure culture industrial yeast selection. We isolated landrace brewing yeast strains from diverse geographical locations across Europe, including Norway, Lithuania, Latvia, Russia, and also included African farmhouse brewing strains from Ghana. Our genomic analysis using long-read and short-read whole genome sequencing uncovered a genetically distinct group that diverges from industrial brewing yeasts. This group, which is closely related to ale brewing strains, is preliminarily named the "European Farmhouse" group and shows greater predicted admixture from Asian fermentation strains. Through genomic and phenotypic analyses, including flavor metabolite analysis via HS-GC-MS, sugar metabolite analysis via HPLC, and wort fermentation analysis, we found a broad spectrum of fermentation capabilities, from rapid and efficient fermentation to unique aroma and flavor compound profiles, potentially offering novel traits for brewing applications. This study highlights the importance of preservation of brewing cultural heritage knowledge and resources including yeast cultures. Key PointsO_LIA large set of geographically diverse farmhouse brewing strains were characterized C_LIO_LINorwegian and Baltic farmhouse brewing strains form a distinct genetic group C_LIO_LIFarmhouse strains show considerable diversity in fermentation and flavour formation C_LI

microbiology↗

bioRxiv2021

Kveik brewing yeasts demonstrate wide flexibility in beer fermentation temperature and flavour metabolite production and exhibit enhanced trehalose accumulation

AO_SCPLOWBSTRACTC_SCPLOWTraditional Norwegian Farmhouse ale yeasts, also known as kveik, have captured the attention of the brewing community in recent years. Kveik were recently reported as fast fermenting thermo- and ethanol tolerant yeasts with the capacity to produce a variety of interesting flavour metabolites. They are a genetically distinct group of domesticated beer yeasts of admixed origin with one parent from the "Beer 1" clade and the other unknown. While kveik are known to ferment wort efficiently at warmer temperatures, its range of fermentation temperatures and corresponding flavour metabolites produced, remain uncharacterized. In addition, the characteristics responsible for its increased thermotolerance remain largely unknown. Here we demonstrate variation in kveik strains at a wide range of fermentation temperatures and show not all kveik strains are equal in fermentation performance, flavour metabolite production and stress tolerance. Furthermore, we uncovered an increased capacity of kveik strains to accumulate intracellular trehalose, which likely contributes to its increased thermo- and ethanol tolerances. Taken together our results present a clearer picture of the future opportunities presented by Norwegian kveik yeasts and offer further insight into their applications in brewing.

microbiology↗

bioRxiv2017

Traditional Norwegian Kveik Yeasts: Underexplored Domesticated Saccharomyces cerevisiae Yeasts

Human activity has resulted in the domestication of Saccharomyces cerevisiae yeasts specifically adapted to beer production. While there is evidence beer yeast domestication was accelerated by industrialization of beer, there also exists a home-brewing culture in western Norway which has passed down yeasts referred to as kveik for generations. This practice has resulted in ale yeasts which are typically highly flocculant, phenolic off flavour negative (POF-), and exhibit a high rate of fermentation, similar to previously characterized lineages of domesticated yeast. Additionally, kveik yeasts are highly temperature tolerant, likely due to the traditional practice of pitching yeast into warm (>30 {degrees}C) wort. Here, we characterize kveik yeasts from 9 different Norwegian sources via PCR fingerprinting, phenotypic screens, lab-scale fermentations, and flavour metabolite analysis using HS-SPME-GC-MS. Genetic fingerprinting via interdelta PCR suggests that kveik yeasts form a lineage distinct from other domesticated yeasts. Our analyses confirm that kveik yeasts display hallmarks of domestication such as loss of 4-vinylguaiacol production and high flocculation, and show superior thermotolerance, ethanol tolerance, fermentation rate, and unique flavour metabolite production profiles in comparison to other ale strains, suggesting a broad industrial potential for this group of yeasts.

microbiology↗