Washington: Superoxide-producing bacteria form away from sunlight and live in dark places like lake, ocean depths and underground soils, it has been revealed.
All forms of life that breathe oxygen-even ones that can`t be seen with the naked eye, such as bacteria-must fight oxidants to live.
"If they don`t," says scientist Colleen Hansel of the Woods Hole Oceanographic Institution in Massachusetts, "there are consequences: cancer and premature aging in humans, death in microorganisms."
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.
Now researchers have discovered the first light-independent source of superoxide. The key is bacteria common in the depths of the oceans and other dark places.
The bacteria breathe oxygen, just like humans. "And they`re everywhere-literally," Hansel, co-author of a paper said.
The result expands the known sources of superoxide to the 95 percent of Earth`s habitats that are "dark."
In fact, 90 percent of the bacteria tested in the study produced superoxide in the dark.
"Superoxide has been linked with light, such that its production in darkness was a real mystery," 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 said.
"This finding shows that bacteria can produce superoxide in the absence of light," she added.
The bacteria are found "miles beneath the seafloor, in hot fluids coming from underwater volcanoes, in every type of underground soil and throughout deep lake and ocean waters," Hansel said.
The findings are published in the journal Science Express.