Researchers looking for alternatives to fossil fuels say they may have found an unlikely ally in certain strains of wine yeast. Their discovery could lead to clean energy sources that make economic sense.
Scientists have been exploring biofuels for decades now, hoping to find a replacement for gasoline. The problem has often been developing a biofuel that is price competitive with good old unleaded. For example, in Brazil, which produces a third of the world's bioethanol, glucose is obtained from sugar cane and fermented into ethanol. In the world's largest bioethanol producer, the United States, starch is harvested from corn for bioethanol.
The problem is that both are popular crops for food. Corn-based ethanol is not economically efficient and only survives thanks to government subsidies. And one famous study showed that the amount of emissions produced by corn and sugar cane ethanol production were similar to those produced by oil.
An alternative to corn, sugar cane and other crops are wild grasses and inedible plant parts, like switchgrass and corn stover. But a great deal of the sugar in such plants comes in the form of xylose, and there is currently no known strain of yeast found that can convert xylose to ethanol efficiently enough to compete with corn and sugar.
Scientists at the department of genetics at Stanford University published a study in June in the Public Library of Science periodical Genetics that focused on finding an efficient yeast to break down xylose into a usable biofuel. According to one of the scientists working on the project, Gavin Sherlock, the team was able to identify 38 strains of yeast that can convert xylose into ethanol. All 38 are strains of yeast for winemaking.
"We were able to identify the gene responsible for this ability, which carries out one of the steps by which cells use this sugar," Sherlock said. "We found that this gene exists widely in wine yeasts, though there are certainly many strains that do not have it."
Despite the allure of wine-yeast-created biofuel, Sherlock says there are still challenges. "I think it is possible that yeast strains derived from wine yeasts may at some point in the future be used for production of ethanol from green plant material," he said. "But that is likely several years off, as the effect that we observed was very modest."
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