Almost 80 percent of the air we breathe consists of nitrogen. All living things need the gas to build proteins and other materials, but only a few organisms can actually convert nitrogen from the air into a form we can absorb. Now researchers from Michigan State University have found a new group of these so-called nitrogen fixers in bacteria. "Spirochetes are a large group of bacteria in which nitrogen fixation had never been recognized before," co-author John Breznak says.

The researchers discovered the spirochetes' nitrogen-fixing ability by looking at termites. These insects can't convert nitrogen themselves, and their diet is very low in it. But Breznak's team extracted spirochetes from the termites' guts and grew the bacteria in the laboratory. Further analysis revealed that the bacteria contained the genes for nitrogen fixation and carried out the fixation process as well.

"Given the ubiquity of spirochetes in freshwater and marine habitats, our work reveals that spirochetes are newly discovered participants in this globally important process," Breznak says. He hopes that their findings, which were published on Friday in Science, will show that microbes are an important part of the ecosystem. "Microbes can contribute to animal nutrition and health, not just cause disease," he says.