United States Department of Agriculture (USDA) researchers have identified a naturally occurring bacterium that can break down key compounds responsible for smoke taint in wine grapes. The development, scientists say, could help growers and winemakers salvage crops affected by wildfire exposure.
Scientists with the USDA’s Agricultural Research Service (ARS) and collaborators reported that Gordonia alkanivorans, a bacterium found on grape leaves, can degrade guaiacol—one of the primary phenols linked to the smoky and ashy flavors that render smoke-exposed grapes unsuitable for winemaking.
Smoke taint occurs when grapes absorb volatile compounds from wildfire smoke. The plant binds these compounds with sugars and stores them in the fruit, which later releases undesirable flavors during fermentation.
This has become a multibillion-dollar issue for the US wine industry as wildfires become more frequent and intense.
In the study, researchers from the ARS Plant Gene Expression Center in Albany, California, sequenced two types of Gordonia alkanivorans and analyzed their guaiacol metabolism.
“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 team identified a gene, guaA, that encodes an enzyme that converts guaiacol into a harmless compound. The enzyme specifically targets guaiacol without affecting other phenols, which also contribute to the wine’s flavor and color profile.
Researchers said the findings demonstrate the potential of using microbes as a targeted, biological approach to mitigating the issue.
“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 involved collaboration with the University of California, Merced; Oak Ridge National Laboratory; and Washington State University’s Viticulture and Enology Program.
*All images are referential.
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