Preiss Richard, Tyrawa Caroline, Krogerus Kristoffer, Garshol Lars Marius, van der Merwe George
Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, Canada.
Escarpment Laboratories, Guelph, ON, Canada.
Front Microbiol. 2018 Sep 12;9:2137. doi: 10.3389/fmicb.2018.02137. eCollection 2018.
The widespread production of fermented food and beverages has resulted in the domestication of yeasts specifically adapted to beer production. While there is evidence beer yeast domestication was accelerated by industrialization of beer, there also exists a farmhouse 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 flavor negative (POF-), and exhibit a high rate of fermentation, similar to previously characterized lineages of domesticated yeast. Additionally, kveik yeasts are reportedly high-temperature tolerant, likely due to the traditional practice of pitching yeast into warm (>28°C) wort. Here, we characterize kveik yeasts from 9 different Norwegian sources via PCR fingerprinting, whole genome sequencing of selected strains, phenotypic screens, and lab-scale fermentations. Phylogenetic analysis suggests that kveik yeasts form a distinct group among beer yeasts. Additionally, we identify a novel POF- loss-of-function mutation, as well as SNPs and CNVs potentially relevant to the thermotolerance, high ethanol tolerance, and high fermentation rate phenotypes of kveik strains. We also identify domestication markers related to flocculation in kveik. Taken together, the results suggest that Norwegian kveik yeasts are a genetically distinct group of domesticated beer yeasts with properties highly relevant to the brewing sector.
发酵食品和饮料的广泛生产导致了专门适应啤酒生产的酵母的驯化。虽然有证据表明啤酒酵母的驯化因啤酒工业化而加速，但挪威西部也存在一种农家酿造文化，世代相传着一种名为“kveik”的酵母。这种做法产生了通常高度絮凝、酚类异味阴性（POF-）且发酵速率高的爱尔酵母，类似于先前鉴定的驯化酵母谱系。此外，据报道，kveik酵母耐高温，这可能是由于传统上将酵母接种到温热（>28°C）麦芽汁中的做法。在这里，我们通过PCR指纹图谱、选定菌株的全基因组测序、表型筛选和实验室规模发酵，对来自9个不同挪威来源的kveik酵母进行了表征。系统发育分析表明，kveik酵母在啤酒酵母中形成了一个独特的群体。此外，我们鉴定出一个新的POF功能丧失突变，以及可能与kveik菌株的耐热性、高乙醇耐受性和高发酵速率表型相关的单核苷酸多态性（SNP）和拷贝数变异（CNV）。我们还鉴定出与kveik中絮凝相关的驯化标记。综合来看，结果表明挪威kveik酵母是一组遗传上不同的驯化啤酒酵母，其特性与酿造行业高度相关。
