The Microbiome Code Breaker

Microbe maven is exploring the chemistry of our bodies’ bacteria

The human microbiome is full of mysteries, and Emily P. Balskus is out to solve them. Take the case of trimethylamine. For more than 100 years, scientists had known that bacteria living in our gut convert the essential nutrient choline to trimethylamine. That trimethylamine bacterial by-product has been linked to diseases both common, such as heart disease, and rare, such as the metabolic disorder known as fish malodor syndrome.

But scientists had no idea about the underlying genetics of this process or which enzyme was cleaving choline’s C–N bond to generate trimethylamine. Balskus, a chemist at Harvard University, decided to track down the biochemical culprit. In 2012, her lab identified the gene cluster responsible for the reaction as well as the glycyl radical enzyme that does the chopping. It turns out that this kind of chemistry had never been seen before from enzymes in this family. Now scientists are wondering if they can target the enzyme to curb heart disease.

When microbiologists began to study the human microbiome, they focused on the kinds of bacteria populating our bodies, Balskus explains. But the real secret to understanding and manipulating the human microbiome isn’t about what these organisms are so much as it is about what they do. By identifying and targeting those biochemical processes, scientists might then begin to manipulate them. “And this,” Balskus says, “presents an enormous opportunity for chemists.”—Beth Halford