New Yeast Discovered in B.C. Wineries
UBC researchers are using genomics to isolate new yeasts that impart a flavour profile specific to B.C. soils.
For hundreds of years, humans have used a certain species of yeast to brew beer and ferment wine. Saccharomyces cerevisiae (S. cerevisiae) is a powerhouse microorganism that is widely used for its reliability to convert the sugars in grapes into alcohol and create a consistent finished product.
However, some winemakers let the environment shape the flavour of their wines, using wild yeast to influence their fermentations. In the Okanagan Valley, Dr. Vivien Measday and her students have used whole genome sequencing to identify a new clade or family of wine yeast in BC vineyards and wineries.
“Yeast has been domesticated just like farm animals have,” Measday says. “These Pacific West Coast Wine yeasts are completely new! We are the first group to find wild S. cerevisiae strains in wine in Canada that are so different from European commercial strains.”
“Yeast is heavily involved in the flavour and aroma compounds of wine. A different genetic makeup could mean a novel flavour profile,” current PhD student Jay Martiniuk adds. “A profile that may be unique to B.C. growing regions.”
From her undergraduate in biochemistry to a PhD focused on S. cerevisiae as a model organism, Measday has spent over 30 years studying yeast. Now as an associate professor at the UBC Wine Research Centre, she is deeply interested in yeast diversity for applications in the wine industry.
Martiniuk brings industry experience to his research. After years of working in wineries, he entered UBC’s food science program to investigate the scientific why’s and how’s of winemaking. During his Master of Science program in Food Science, Martiniuk carried out the first wine grape yeast isolation research project in Measday’s lab. They have worked closely in wine sciences ever since.
The Process: From Field to Lab
The Measday lab tests samples from each step: from grapes sampled in the vineyard, to the initial crush of the grapes, then from early-, middle-, and late-stage fermentation. Researchers in the lab isolate dozens of yeast species and strains in each fermentation, noting which ones are able to outcompete and survive to the end product.
To get a full picture of the S. cerevisiae strains from each vineyard, Martiniuk developed a protocol that captures a DNA fingerprint of each yeast strain. He focuses on specific regions of the genome to categorize strains of similar makeup and differentiate strains that have been used commercially versus those that are unique.
“So much of this work is collaborating with wineries, who are looking to define their terroir,” Martiniuk says, referring to the environmental factors that affect a crop of wine grapes. “These wild yeasts may have a more unique winemaking traits, which could lead to a more interesting aroma and flavour profile in wines.”
Measday and Martiniuk have collected isolates of several thousand yeasts, and Measday’s lab has identified over 200 S. cerevisiae strains in the Okanagan Valley. After isolating and prioritizing the strains, the lab sends particularly novel strains to another centre for whole genome sequencing.
“They report back every single facet of the DNA sequence,” Measday says. “This detailed view can tell us how the yeast may perform in fermentation and what traits may allow it to survive in the environment.” Measday’s other students, PhD candidates Alex Marr and Jackson Moore, analyzed the whole genome sequencing data to identify this new family of Pacific West Coast Wine yeast.
The lab now has a collection of yeasts from the region. If they find a specific genetic makeup that delivers a preferred flavour profile, they can grow and potentially commercialize that strain.
Measday and Martiniuk have studied twelve vineyard sites and several different wineries in the Okanagan Valley. Their lab is now shifting towards Vancouver Island’s quickly growing wine industry.
“It’s geographically quite isolated from the rest of the province,” Martiniuk says. “We’re hoping that isolation has produced strains that are quite genetically different from the Valley.”
Although they have just started the DNA fingerprinting process on Vancouver Island, the lab has already seen a difference in yeast species. While the Okanagan Valley vineyards surveyed in their research were mostly populated by S. cerevisiae, Vancouver Island may also have other species such as Saccharomyces paradoxus and Saccharomyces uvarum. Martiniuk notes that S. uvarum behaves differently in fermentation, preferring colder temperatures as low as 12ºC compared to S. cerevisiae’s 25-30ºC range.
New Yeasts in B.C. Winemaking
Winemakers in B.C. have been excited to know what lives in their fields and tanks.
“It’s important to know what you want and don’t want in your tanks,” Measday says, explaining spontaneous fermentation, which uses wild yeasts. “The native microorganisms could overpower the wine or impart undesirable flavours altogether.”
One winery in the Okanagan, Okanagan Crush Pad, in collaboration with graduated MSc student Elia Castellanos, has already tested pilot-scale production with a couple of new Pacific West Coast Wine strains. Measday and Martiniuk hope that their research can add predictability and reliability to B.C.’s endemic yeasts.
Selected Papers:
Marr RA^, Moore J^, Formby S, Martiniuk JT, Hamilton J, Ralli S, Konwar K et al. Whole genome sequencing of Canadian Saccharomyces cerevisiae wine strains reveals four subpopulations with similarity to North American oak, sake, and commercial strains. G3: Genomes, Genes, Genetics, Volume 13, Issue 8, August 2023, jkad130
Cheng E^, Martiniuk JT^, Hamilton J, McCarthy GC, Castellarin SD, Measday V. 2020. Characterization of Sub-Regional Variation in Saccharomyces Populations and Grape Phenolic Composition in Pinot Noir Vineyards of a Canadian Wine Region. Frontiers in. Genetics. Aug 31; 11:908.
Martiniuk JT, Pacheco B, Russell G, Tong S, Backstrom I, Measday V. 2016. Impact of commercial strain use on Saccharomyces cerevisiae population structure and dynamics in Pinot Noir vineyards and spontaneous fermentations at a Canadian winery. PLOS ONE 11(8): e0160259.
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