Wildfires are becoming more frequent and severe on the U.S. West Coast—a region that produces the vast majority of the country’s wine. The resulting smoke has proven to be a costly problem for winemakers, tainting billions of dollars’ worth of product with an unwanted smoky flavor.
Fortunately, scientists may have found a clever solution. In a new study published Wednesday in the journal Plos One, researchers led by Claudia Castro of the U.S. Department of Agriculture’s Agricultural Research Service identified two strains of Gordonia alkanivorans that break down guaiacol—a compound in wildfire smoke that taints the flavor of wine.
The team honed in on the specific genes that give the bacteria this ability, opening the door to biotechnologies that could combat the effects of wildfire smoke contamination.
“Smoke taint in wine has caused significant economic losses for the wine industry in recent years,” the study states. “For example, California and Oregon lost $3.7 billion due to smoke taint in 2020. As a result, the wine industry is in dire need of new technology to help alleviate this challenging biochemical problem.”
Harnessing the power of a grape plant’s microbiome
Burning plant matter emits guaiacol and other volatile phenols, or aromatic organic compounds. When wine grapes absorb these phenols, they get released during the winemaking process, giving the finished product a smoky, ashy taste known as “smoke taint.”
Previous studies have shown that certain species of soil-dwelling bacteria can break down guaiacol, but few have explored whether the bacteria present in the microbiome of grape plants have this ability. To investigate this, Castro and her colleagues harvested leaves from chardonnay and cabernet grape plants, then tested them for guaiacol-eating bacteria.
The researchers identified two strains of G. alkanivorans that use guaiacol as their sole carbon source. Then, they sequenced their genomes, identifying the suite of genes that allows them to perform this function. When they deleted one of these genes—called guaA—from the DNA of G. alkanivorans cells, the bacterium was no longer able to break down guaiacol, confirming that they found the genetic key to microbial guaiacol degradation.
A path to new solutions
While the researchers don’t outline any specific ways the wine industry could harness these bacteria—or the guaA gene itself—to protect grapes from wildfire smoke contamination, there are several types of solutions that could stem from the findings.
For one, applying the bacteria directly to wine grape plants after smoke exposure may reduce the amount of guaiacol absorbed into the fruit. Researchers could also develop ways to encourage the growth of these bacteria and strengthen the plants’ natural defenses. Alternatively, wine producers could introduce these microbes during the winemaking process to break down guaiacol before they bottle the finished product.
It will require further research to develop practical solutions and ensure they are safe for the plants, agricultural workers, and wine consumers. This study outlines one promising potential avenue for addressing smoke taint. As global temperatures rise and wildfires become increasingly common in the western U.S., the future of the nation’s wine industry will depend on innovative solutions to smoke contamination.