A new University of Michigan study has overturned a century-old assumption about one of the most common bacteria living in our lungs.
Prevotella melaninogenica — a species that accounts for roughly 10% of the microbial population in healthy lungs and up to 13% on average in people with respiratory disease — has long been classified as an obligate anaerobe, a microbe supposedly incapable of surviving in the presence of oxygen. That never quite squared with where it actually lives.
The team, led by asthma researcher Ariangela Kozik at U-M Medical School, cultured P. melaninogenica under increasing levels of oxygen. They found the upper threshold for growth sits between 5% and 8% oxygen — and that the bacteria could briefly survive levels as high as 21%, the concentration in ordinary air.
Using a new real-time sensor platform and RNA sequencing, the researchers also found that Prevotella appears to consume oxygen and cope with oxidative stress and DNA damage differently than other aerobic bacteria.
"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," Kozik said.
The ability to exist in the presence of oxygen may lie along a spectrum rather than a clear-cut binary, the researchers argue. Better understanding how these microbes behave in the lung could clarify their role in conditions like asthma and COPD — and eventually help drive more targeted therapies. The work is published in the Journal of Bacteriology.
