A team of Missouri S&T students recently created a breathalyzer using cultured yeast cells and an E. coli-infested bacterium that changes colors in response to the presence of sugar. But they weren’t trying to gross each other out with creepy inventions. They were participating in a competition at MIT last November.

The International Genetically Engineered Machine competition, or iGEM, pits 37 teams of university students against one another in the quest to develop genetically engineered machines designed to make living cells perform specific tasks not typically found in nature.

In the case of the breathalyzer, the students used their knowledge of biochemical reactions to make the yeast cells produce a visual response to the presence of ethanol. Then they engineered a device that could display an individual’s blood alcohol level.

“The iGEM students are learning skills that will have applications in the development of biosensors,” says David J. Westenberg, associate professor of biological sciences at Missouri S&T and one of the team’s advisors.