Fruit Flies & Beer—The Other Organism Obsessed with Oktoberfest

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It's October, which to most means it's time to break out the steins and German beers to celebrate the festival of Oktoberfest. But when you're drinking your brew and you whiff that intoxicating familiar "fresh beer smell", you're actually smelling an evolutionary trick that has helped a common bacteria thrive. Thanks to fruit flies, no less!

Discovering quite an unlikely and yet unbelievably effective messaging pathway between the common brewer's yeast found in beer and the fruit flies that swarm around it, researchers from Belgium were able to add a bit of evolutionary history to that of the Oktoberfest folklore. Publishing their results in the latest issue of the journal Cell Reports, the researchers led by professor Kevin Verstrepen found that much like ripening fruits, yeast cells developed a way of producing pleasant and appetizing aroma compounds that effectively draw in flies to disperse the yeast cells in the environment.

"Two seemingly unrelated species, yeasts and flies, have developed an intricate symbiosis based on smell" Verstrepen says. "The flies can feed on the yeasts, and the yeasts benefit from the movement of the flies."

Teaming up with fruit fly neurobiologists Bassem Hassan and Emre Yaksi, the team was able show that the brains of the fruit fly were activated by chemical compounds attributed to the aromas put off by beer, and as was expected, mutant yeast beer that lacked the gene encoding for the compound was far less attractive to the fruit fly candidates. In turn, mutant yeast strains found that their dispersal and growth in range was abysmal in comparison to their aromatic counterparts.

While the research only investigated the relationship between fruit flies and brewer's yeast, to find an evolutionary overlap that created a unique smelling symbiosis between two species, the researchers indicate that the discovery may have implications far beyond the brewing and the bars. The research may suggest that the lives and histories of microbes and insects may be far more intertwined than previous research led us to believe.

"Our results uncover the molecular details of an intriguing aroma-based communication and mutualism between microbes and their insect vectors" Verstrepen says. "Similar mechanisms may exist in other microbes, including microbes on flowering plants and pathogens.