May 3, 2013 — Breathing oxygen ... can be hazardous to your health?
Indeed, our bodies aren't perfect. They make mistakes, among them producing toxic chemicals, called oxidants, in cells. We fight these oxidants naturally, and by eating foods rich in antioxidants such as blueberries and dark chocolate.
These same oxidants also exist in the environment. But neutralizing environmental oxidants such as superoxide was a worry only for organisms that dwell in sunlight -- in habitats that cover a mere 5 percent of the planet.
That was the only place where such environmental oxidants were thought to exist.
The bacteria breathe oxygen, just like humans. "And they're everywhere -- literally," says Hansel, co-author of a paper reporting the results and published in this week's issue of the journal Science Express.
"Superoxide has been linked with light, such that its production in darkness was a real mystery," says Deborah Bronk of the National Science Foundation's (NSF) Division of Ocean Sciences, which co-funded the research with NSF's Division of Earth Sciences.
The number of these bacteria in a thimble of seawater or soil is greater than the human population of San Francisco. And they're all releasing large amounts of superoxide.
"That's a paradigm shift that will transform our understanding of the chemistry of the oceans, as well as of lakes and underground soils," says Hansel, "and of the life forms that live in and depend on them."
Co-authors of the paper are Julia Diaz and Chantal Mendes of Harvard University, Peter Andeer and Tong Zhang of Woods Hole Oceanographic Institution and Bettina Voelker of the Colorado School of Mines.
- J. M. Diaz, C. M. Hansel, B. M. Voelker, C. M. Mendes, P. F. Andeer, T. Zhang. Widespread Production of Extracellular Superoxide by Heterotrophic Bacteria. Science, 2013; DOI: 10.1126/science.1237331
Note: If no author is given, the source is cited instead.