More Wine, Less Smoke Please

Life is too short to drink bad wine. ARS researchers are helping American grape growers and winemakers save wine grapes impacted by wildfires by finding a natural solution to remove the unpleasant flavors caused by smoke taint – a multibillion dollar problem in the U.S. wine industry.  

Smoke taint occurs when wine grapes are exposed to high levels of smoke in a vineyard and absorb volatile compounds from the smoke. The leaves and grapes attach sugars to the smoke compounds and store them, which results in unpleasant flavors in the wine, often described as tasting “smoky” or “ashy”. Consequently, most grapes exposed to wildfire smoke become unsuitable for making wine. 

In a research study, researchers from the ARS Plant Gene Expression Center in Albany, CA, and their collaborators found that Gordonia alkanivorans, a bacterium that can occur naturally on grape leaves, is able to break down guaiacol, one of the main phenols responsible for smoke taint in wine. Phenols are naturally occurring chemical compounds that are responsible for much of the flavor and color in wine.

“We found two strains of the same species of Gordonia alkanivorans that can use guaiacol as their only food source,” said Devin Coleman-Derr, ARS Research Molecular Biologist. 

The researchers sequenced the strains’ genomes and studied which genes were active when Gordonia alkanivorans were given access to guaiacol. They found that a gene called guaA produced an enzyme that was key to breaking down guaiacol into a harmless compound. Furthermore, the guaA enzyme broke down only guaiacol and not the other phenols. 

According to Coleman-Derr, even though guaiacol is just one of several phenols potentially responsible for smoke taint, the findings show that using bacteria as a biotechnological tool in treating smoke taint is a potential solution. 

“This research provides a roadmap for finding bacteria and other microbes that can target other problematic chemicals in or on plants,” said Coleman-Derr. 

The research was done in collaboration with University of California, Merced’s Department of Molecular and Cell Biology, Oak Ridge National Laboratory’s Biosciences Division, and Washington State University’s Viticulture and Enology Program. – by Jessica Ryan, ARS Office of Communications

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