Graduate Thesis Or Dissertation
 

Enrichment Isolation of Brettanomyces Yeasts to Probe the Relationship Between Vineyard and Winery Populations

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https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/wm117w352

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  • The budding yeast Brettanomyces bruxellensis has the potential to spoil fermented beverages and cause financial losses, but also contribute positively to certain products such as Lambic beer. It is most notorious for causing “Brett” spoilage of wine, which is characterized by undesirable aromas such as “bandaid” and “barnyard”, therefore most research on this species has focused on understanding this impact. However, little is known about the ecology and physiological properties of this species outside of isolates obtained from within fermentation facilities. A limited number of previous studies have had mixed success enriching B. bruxellensis from vineyards, and there have been no comprehensive comparisons of populations from vineyards and wineries, to establish their connectivity. In this work, enrichment culturing using a new, simplified enrichment media (Brettanomyces Enrichment Media - BEM) was successfully applied in the recovery of 12 isolates of B. bruxellensis from a vineyard in Oregon. While BEM did restrict the growth of common vineyard yeasts likely to out-compete B. bruxellensis in enrichment cultures, several other yeast species infrequently described in vineyard ecology, such as Nakazawea ishiwadae and Ogataea polymorpha were recovered. Investigation into the competitive nature of these yeasts in BEM suggests that the relatively slow growth of B. bruxellensis relative to other vineyard yeast is the main factor hampering successful enrichment. In parallel, whole genome sequencing was performed on 120 B. bruxellensis isolates from New Zealand wineries. The goal of this sequencing was to compare winery populations from different winemaking regions around the world and serve to generate baseline data against which Oregon winery and vineyard isolates could be compared. Analysis of the sequenced B. bruxellensis isolates revealed grouping into five distinct clades, consistent with results from other recent genome-sequencing studies. However, the relative distribution of isolates in these groups differed from previous studies, with New Zealand isolates exhibiting lower relative abundance of sulfite tolerant isolates compared to previous studies in Europe and Australia. Future work will involve genome sequencing of the Oregon vineyard and winery isolates gathered in this study, and evaluation of their phylogenetic relatedness to one another and other winery populations of B. bruxellensis from other wine producing regions. Doing so may reveal the possible movement of B. bruxellensis from the vineyard to the winery, a relationship that has long been suspected. Such evidence could shed light upon the origins of B. bruxellensis infection in the winery.
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  • Intellectual Property (patent, etc.)
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  • 2020-09-21 to 2021-04-22

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