Single-celled fungus yeast is essential to humans, a linchpin in the production of bread, beer, wine, and biofuels, among many applications.

Now, biologists at the University of Iowa have found that a new type of genetic variation in yeast can improve ethanol production. In a recent study, the biologists report from experiments that yeast strains with certain alleles of a key gene are more efficient at fermentation. An allele is one of several forms of a gene, usually arising through mutation, that is responsible for hereditary variation.

The key yeast gene is MED15. The biologists, led by Jan Fassler, professor in the Department of Biology, found that yeast used to make wine has different alleles of MED15, and that they were better at fermentation than strains of yeast used in the lab, or presumably in other domestication niches.

“While the yeast used to make bread and the yeast used to make wine are part of the same family, the different versions of genes like MED15 can help explain why a yeast used to make bread would be suboptimal when making wine,” Fassler says.

The findings may help scientists who seek to engineer a better yeast strain to make wine more efficiently or to produce more bioethanol for fuel.

The results were published online on Oct. 18 in the journal Frontiers of Microbiology.

David Cooper, Yishuo Jiang, and Sydney Skuodas, are contributing authors who were graduate students at the time of the study, while contributing author Luying Wang was an undergraduate student.