The known smell of beer is because of the aroma compounds produced by common brewer’s yeast. Recently, researchers stated in the ‘Cell Reports’ journal that they discovered why yeast (S. Cerevisiae), produce that smell. The scent magnetizes fruit flies, which eventually repay the yeast by diffusing their cells in the environment.

Certainly, yeast lacks a single aroma gene due to which it fails to produce their distinctive odor and that’s why they don’t have the ability to attract fruit flies.

Kevin Verstrepen of KU Leuven and VIB in Belgium stated that, “Yeast and flies, two apparently discrete species have developed an obscure symbiosis based on smell. Flies can feed on the yeast, and ultimately yeast benefits from the movement of flies.”

Verstrepen, a graduate student, who first got an idea that how yeast cells contribute to the flavor of of beer and wine. He found that the yeast cells make numerous pleasing aroma compounds similar to those produced by ripening fruits. Particularly, one gene in yeast known as ATF1 for alcohol acetyl transferase was actually responsible for the sharing of those impulsive compounds.

Verstrepen further stated that, “As I returned to the lab after a weekend, I found the flask containing smelly yeast is infested with fruit flies and on the other hand, another flask which contained a mutant yeast strain in which the aroma gene was deleted did not contain flies.”

But it wasn’t until years later, when I met two of the fruit fly neurobiologists Emre Yaksi and Bassem Hassan and the story begins.

With the combination of molecular biology, neurobiology and the behavioral tests, the researchers found that the loss of ATF1 actually alters the response of the fruit fly brain to a smell of yeast. Consequently, the flies are less attracted to yeast cells, which eventually resulted in the reduced dispersal of yeast mutant by the flies.

Moreover, the researchers stated that, the findings expose a fascinating aroma-based communication and mutualism between microbes and insects. They further infer that the similar mechanism happens in other plant associated microbes, especially pathogens.

Indeed, the team of researchers has secluded diverse yeast species from the flies bodies in nature to discover that the vast majority of yeast produces aroma compounds. They have isolated several strong aroma-producing yeasts from flowers too.