Better wine, one yeast cell at a time

Better wine, one yeast cell at a time

A wine-loving scientist engineers wine yeast to build a better glass of wine
September 29, 2011

Hennie J. J. van Vuuren is among the 30 percent of adults around the world who exhibit allergic reactions to young red wines — something that has inspired the University of British Columbia (UBC) wine biotechnologist to create a new yeast strain capable of eliminating the allergens altogether.

“A huge number of people who love wine cannot drink it because they get severe headaches,” says van Vuuren, a South African native who founded UBC’s Wine Research Centre in 1999. “So I thought, how could I get rid of this problem?”

The solution took 15 years — seven for research and eight for testing. During that time, van Vuuren inserted a gene from the bacterium that converts malic acid to lactic acid into the Saccharomyces cerevisiae wine yeast. The result has been the creation of “ML01,” a genetically modified yeast strain that not only eliminates the molecules that cause the headaches but also vastly simplifies the production process for the commercial wine industry. 

In 2009, this industry collectively produced almost three billion litres of wine in North America alone, with the single biggest producer, California, earning $18.5 billion in domestic retail sales in 2010. According to Statistics Canada’s latest data (2006), Canadian winemakers generated $784.5 million that year and directly employed 2,766 people.

Makers of red wine and white Chardonnay have historically prepared wine in a two-step fermentation process. First, the grape juice (called “must”) is fermented with yeast, and then lactic acid bacteria is applied to deacidify the wine and ensure its microbial stability. The second step creates the allergy-inducing molecules. The use of ML01 eliminates these molecules and completes both fermentation processes in a single step.

This is important because the so-called malolactic bacteria added in the second process are expensive and unreliable. Van Vuuren knows commercial winemakers who have had to wait eight months for the secondary fermentation. Such delays are costly, since they increase the potential for spoilage and limit a winery’s production capacity.

To date, two of van Vuuren’s genetically modified wine yeasts have been commercialized: ML01 and a second yeast that reduces ethyl carbamate, a potentially carcinogenic by-product of wine production. Both yeast strains have received approval for use in Canada and the United States and are licensed to separate private-sector companies: ML01 to the Lesaffre group, a French multinational yeast company of 7,000 employees worldwide; the second yeast to Vancouver-based Functional Technologies, which currently employs 31 people. 

To create this second wine yeast, van Vuuren isolated and modified a yeast gene that breaks down a compound called urea, which reacts with ethanol to produce ethyl carbamate. The result reduces the carcinogenic by-product by 90 percent. “This is the first genetically engineered product that benefits the consumers, not the producers,” he says.  

About 2,000 kilograms of van Vuuren’s ML01 yeast will be sold to commercial wineries in North America in 2012, which will produce about 100,000 litres of wine. The ethyl carbamate-reducing yeast has yet to generate revenue.   

In the 12 years since van Vuuren founded the Wine Research Centre, the number of scientists researching the molecular genetics of wine yeasts at the facility has risen from five in 1999 to 28. Van Vuuren currently has two new yeast patents in development: one that will reduce the alcohol content of wine without sacrificing body and taste and another that will limit the concentration of acetic acid in the wine-production process. High acetic acid levels give wine a vinegar smell.

Without funding from the Canada Foundation for Innovation, says van Vuuren, his work developing new yeasts at UBC would not have been possible. Scientists at the Wine Research Centre have access to the CFI-funded $2.06 million Laboratory of Molecular Biophysics, which provides state-of-the art equipment for characterizing gene products. Van Vuuren has also been able to make exacting comparisons between his genetically modified yeasts and normal yeast cells thanks to the CFI’s $60,844 investment to upgrade UBC’s DNA Microarray Core Facility.

“It’s a fantastic facility,” says van Vuuren. “Without it, I would have had to send my work to someone else to do.”