Identification and characterization of indigenous B.C. wine yeast strains

在竞争激烈的葡萄酒市场中，不列颠哥伦比亚省(BC)的葡萄酒厂必须生产出高价值的葡萄酒，以表现其所在地区的独特特征或地形。葡萄酒是通过接种酿酒酵母商业菌株进行发酵或自然发酵生产的，自然发酵依赖于驻留在葡萄和酿酒设备上的酵母。自发发酵是有风险的，但如果本土酵母菌在发酵过程中占主导地位，则可以生产出具有有机感官的复杂葡萄酒。我的研究目标是确定卑诗省葡萄园中存在的具有酿酒潜力的本土酵母，展示卑诗省的土地。自2013年以来，我们已经与两家卑诗省葡萄酒厂合作，进行灰比诺和黑比诺自发发酵。在酿酒厂发酵的同时，我们收获了相同的葡萄品种，并在实验室进行了发酵。我们从酿酒厂和葡萄园发酵中分离出酿酒酵母菌株，进行微卫星图谱分析，并将数据与我们编制的120多个商业酿酒酵母菌株的微卫星数据库进行比较。我们已经确定了一个独特的本土酿酒酵母亚群，并在发酵过程中意外地发现了巴扬链霉菌株。我们的新的酿酒酵母和巴扬氏酵母菌株都具有酿酒潜力。*目的1.从自然发酵中分离的酿酒酵母菌株的表型和代谢谱。对我们的酿酒酵母菌株进行的贝叶斯聚类分析显示，有12个群体聚类。我们将对每个集群中的代表性菌株进行小规模发酵。具有旺盛发酵特征的菌株将被分析为阳性风味化合物。将对葡萄酒生产的重要性状进行表型分析，并对具有酿酒潜力的菌株进行全基因组测序。*目标2.自然发酵过程中酵母/真菌种类的鉴定。像Metschnikowia这样的非传统酵母在自发发酵中被发现，并为葡萄酒带来了感官上的复杂性。我们将通过直接从葡萄酒样品中提取DNA和Illumina下一代测序来鉴定存在于我们的葡萄酒厂和葡萄园发酵中的非酵母菌。我们的目标是分析非常规酵母对酿酒厂和葡萄园发酵的贡献。*目的3.巴彦氏酵母分离株的遗传特征及对巴扬氏酵母和非酵母酵母发酵潜力的评价。我们从灰比诺自发发酵中分离到独特的巴亚氏链霉菌菌株。我们将使用商业菌株和已发表的菌株来生成一个巴耶氏链霉菌参考数据库，以对亚群进行分类。Bayanus和非酵母菌株将与酿酒酵母菌株共接种，以确定理想的菌株组合，以生产高质量的葡萄酒。**

In competitive wine markets, British Columbian (BC) wineries must create high-value wines that express the unique character, or terroir, of their region. Wines are produced by inoculated fermentation with commercial strains of the wine yeast Saccharomyces cerevisiae (S. cerevisiae) or by spontaneous fermentation, which relies on yeast residing on grapes and winery equipment. Spontaneous fermentations are risky but can produce organoleptically complex wines if indigenous yeast species dominate the fermentation. The goal of my research is to identify indigenous yeast present in BC vineyards with enological potential that showcase BC terroir. Since 2013, we have collaborated with two BC wineries that perform Pinot Gris and Pinot Noir spontaneous fermentations. Concurrent with winery fermentations, we harvested the same grape varietals and fermented them in the lab. We isolated S. cerevisiae strains from winery and vineyard fermentations, performed microsatellite profiling and compared the data to a microsatellite database that we compiled of over 120 commercial S. cerevisiae wine yeast strains. We have identified a unique indigenous subpopulation of S. cerevisiae and unexpectedly identified strains of S. bayanus in the fermentations. Both our novel S. cerevisiae and S. bayanus strains have enological potential.***Objective 1. Phenotypic and Metabolic profiling of S. cerevisiae strains isolated from spontaneous fermentations. Bayesian clustering analysis of our S. cerevisiae strains revealed 12 population clusters. We will perform small-scale fermentations with representative strains from each cluster. Strains with vigorous fermentation profiles will be analyzed for positive flavor compounds. Phenotypic analysis of traits important for wine production and whole genome sequencing of strains with enological potential will be performed.***Objective 2. Identification of yeast/fungal species during spontaneous fermentation. Nonconventional yeasts such as Metschnikowia are found in spontaneous fermentations and contribute sensorial complexity to the wine. We will identify non-Saccharomyces species present in our winery and vineyard fermentations by direct DNA extraction from wine samples and Illumina next generation sequencing. Our goal is to analyze the contribution of nonconventional yeast to the winery and vineyard fermentations. ***Objective 3. Genetic characterization of BC S. bayanus isolates and evaluation of S. bayanus and non-Saccharomyces yeast fermentation potential. We isolated unique strains of S. bayanus from Pinot Gris spontaneous fermentations. We will generate an S. bayanus reference database using commercial and published strains to classify subpopulations. S. bayanus and non-Saccharomyces strains will be co-inoculated with S. cerevisiae strains to identify ideal strain combinations for high quality wine production. **