A University of Michigan study has upended a century-old belief about how bacteria survive in the lungs, potentially opening new doors for treating asthma, COPD (chronic obstructive pulmonary disease), and other chronic respiratory diseases. Scientists have long assumed that Prevotella melaninogenica, a bacterium commonly found in the respiratory tract, could not survive in the presence of oxygen. But new research shows this bacterium is far more adaptable than previously thought.

What Did Scientists Discover About Lung Bacteria?

Researchers at the University of Michigan exposed cultures of Prevotella melaninogenica to progressively higher concentrations of oxygen and measured their growth and survival. The results were striking: the bacteria were able to grow at oxygen concentrations between 5 and 8 percent and briefly survived exposure to levels as high as 21 percent, which is the oxygen level in normal air.

Using advanced real-time sensor technology and RNA sequencing, the team also found evidence that Prevotella may consume oxygen and respond to oxidative stress and DNA damage differently from other aerobic bacteria. This suggests the bacterium has survival mechanisms that scientists never appreciated before.

"Prevotella has all of these mechanisms to allow it to survive in oxygenated environments that previously were not appreciated for this organism at all, changing what we thought we knew," said Ariangela Kozik, Assistant Professor of Internal Medicine at the University of Michigan Medical School.

Ariangela Kozik, Assistant Professor of Internal Medicine, University of Michigan Medical School

Why Does This Matter for People With Respiratory Disease?

Prevotella melaninogenica is not just a rare curiosity. The bacterium makes up roughly 10 percent of microbial populations in healthy lungs and as much as 13 percent on average in people with respiratory disease, including asthma and COPD. Understanding how this bacterium actually functions in the lungs could help researchers develop more targeted treatments for these conditions.

Kozik, who specializes in asthma research, notes that Prevotella occurs at different levels in the respiratory tracts of both healthy people and those with chronic lung disease. The fact that it thrives in oxygen-rich environments raises fundamental questions about its role in health and disease.

How Will This Discovery Change Respiratory Disease Research?

• Rethinking Bacterial Classification: Scientists may need to abandon the traditional categories they have used to classify bacteria as either obligate anaerobes (unable to survive with oxygen) or aerobic organisms. Kozik suggests that a bacterium's ability to tolerate oxygen may fall along a spectrum rather than fitting neatly into these binary categories.
• Understanding Immune Response: Kozik's laboratory plans to investigate how the immune system responds to Prevotella and examine lung bacteria more closely to determine how these microbes interact with the body and what signals they send to the immune system.
• Developing Targeted Therapies: A clearer picture of how the body's microbiomes function could eventually contribute to more targeted therapies for chronic lung diseases, moving beyond one-size-fits-all treatment approaches.

"We need to work to look at the bacterial community and ask, how does this community function currently? What metabolites are they making, what signals are they sending to the immune system? How's the immune system responding to it? How does this activity differ in health versus in the context of chronic lung diseases?" explained Kozik.

Ariangela Kozik, Assistant Professor of Internal Medicine, University of Michigan Medical School

The research was published in the Journal of Bacteriology on July 14, 2026, and represents a significant shift in how scientists understand the microbial communities living in human lungs. More than 35 trillion bacteria live throughout the human body, forming microbiomes in the gut, mouth, lungs, skin, and urogenital tract, and researchers increasingly recognize that these microbial communities are connected to both health and disease.

For people living with asthma, COPD, or other chronic respiratory conditions, this discovery suggests that future treatments may be able to target specific bacterial interactions rather than simply trying to eliminate all bacteria. As Kozik noted, much about what individual microbes do and how they survive remains unknown, but this study represents an important step toward filling that knowledge gap.