The microbiome is popularly understood to be the community of bacteria that live and work in our guts and on our skin. But, in fact, those bacteria have a lot of neighbors—including unsung members of the fungal kingdom.

“Everybody talks about the bacteria, but very few investigators look at the fungal side: You also have healthy and not-so-healthy concentrations of fungi on every exposed surface of your body, inside and out,” says David Underhill, PhD, the Janis and William Wetsman Family Chair in Inflammatory Bowel Disease.

Why are these organisms—mainly known for molds and mushrooms—such uncharted territory? Fungal cells are more difficult to study than bacterial cells, which may be more popular subjects because they’re more abundant in our bodies. But Underhill’s lab is looking at ways to manipulate the fungome in animal models to improve human health. His team is studying whether the nature of the fungome in the gut can affect inflammatory bowel disease or even asthma.

“Bacteria in your microbiome influence diverse areas of health—everything from digestion, immune response, reactions to cancer therapy, and even behavioral activities,” he says. “With the discovery of fungi in the microbiome as well, there’s the potential that fungi also influence these processes.”