Early in his career, biological scientist Steven Finkel taught students how to destroy what he now spends his days trying to understand.

In the 1990s, during a postdoc at Harvard Medical School, future doctors were taught how the body works — from the circulatory system to the kidneys and the liver. But when it came to microbes, the message was simple: Destroy them. “The primary interest was to teach students how to kill them,” says Finkel, “because medicine considered them only as disease organisms.”

Today, thanks in part to Finkel’s research into how microbes survive and thrive in environments including the gut, the scientific perspective has radically changed. We now recognize that the teeming worlds inside our bodies — simultaneously alien and intimately close — are crucial to our health and well-being.

“Everyone’s digestive system has a unique resident community of hundreds of bacterial species,” says Finkel, professor of biological sciences and college dean of graduate and professional education. These trillions of microbes may influence everything from our weight to our mood. They not only provide essential vitamins and help train the immune system — some may even provide certain neurotransmitters like dopamine and serotonin, potentially influencing how we feel.

Understanding the Gut Microbiome

Finkel suggests the gut microbiome may wield even more power over us than we realize. “Our bodies are curating our microbiome,” he says. “But our microbiome might also be curating us, by making us do certain things.” For example, there is evidence that some bacteria in the gut can contribute to cravings for foods that are high in fat and sugar.

As well as helping to shape our dietary preferences, the gut microbiome, when unbalanced, can make us ill. An unhealthy microbiome can trigger or exacerbate conditions such as irritable bowel syndrome, diabetes and cardiovascular disease. Yet, researchers still don’t fully understand how this microbial universe operates. “Everyone’s gut is their own universe,” says Finkel, “and we are far from having a complete understanding of how bacteria in the gut interact with each other, and how they interact with each human host.”

Finkel’s lab is working to uncover how microbial communities function — and sometimes fail. He and his team analyze stool samples, cultivate bacteria and study how microbes breathe, eat, grow and die. One of their more surprising discoveries: Gut microbes produce electricity. Bacteria might even communicate using electrical signals. These communication networks may be essential to microbiome health — and when disrupted, Finkel suggests, the resulting “power outages” might contribute to disease.

“We knew that electricity-producing microbes exist in natural environments and even in some sewage treatment plants,” he says. “But no one had previously connected the dots and realized this phenomenon might also be occurring in the human gut.”

Understanding how gut microbiomes function could someday allow scientists to shape them for our benefit. Although the booming probiotic supplement industry promises such benefits, Finkel notes that, at present, more research will be required to make the supplements reliable. We still don’t know enough, he says, to assess the state of someone’s gut microbiome — let alone tailor individualized treatments.

Improving our understanding of the gut microbiome’s composition and activity could one day make personalized treatments possible. “I wouldn’t be surprised if in five to 10 years,” says Finkel, “diagnostics will enable us to assess the state of the gut microbiome and possibly correlate it with a particular disease or health outcome.”

Steve Finkel photo caption: Recently elected a Fellow of the American Association for the Advancement of Science, biological scientist Steven Finkel is exploring the teeming ecosystem inside our gut microbiome.