March 27, 2009 -- Just like humans effortlessly suck up oxygen and breathe out carbon dioxide, some bacteria take in toxic metals and release non-toxic versions. With that natural ability, these microbes have caught the eye of scientists who'd like to put them to work cleaning up nuclear waste sites. A new study brings that goal one step closer to reality. Researchers have identified and located two proteins that give certain bacteria the power to detoxify dangerous metals, including uranium, chromium and technetium. "This was a big step," said Brian Lower, a microbiologist at The Ohio State University in Columbus. "These microorganisms are commonly occurring. If we can harness their abilities to clean up these sites, that would be one way to help prevent harm to the ecosystem, the water supply, and ourselves." Lower and colleagues studied a bacterium called Shewanella oneidensis. About 20 years ago, Shewanella was one of the first groups of microorganisms found to metabolize toxic metals. Ever since, scientists have been trying to figure out how they do it. Related Content:
To investigate, Lower's team used a new technique called antibody-recognition force microscopy. Based on the proteins they suspected they'd find, the researchers put protein-matching antibodies at the tip of a probe. Then, they used the probe to scan the surfaces of individual Shewanella. When the antibodies found a match, a microscope zeroed in and took high-resolution images. The images confirmed what the scientists had expected to find: Both of the proteins they looked for were there, and both proteins -- both types of enzymes -- were sitting on the outside of the bacteria's cell as well as in an ooze-like material that comes out of the cell. In the human body, enzymes stay inside cells, because that's where biological processes happen. But the minerals in metals are insoluble, which means they can't easily penetrate a cell membrane. Shewanella gets around this problem by putting their metal-digesting enzymes outward. The new findings, reported in the journal Applied and Environmental Microbiology, give some insight into the history of life on Earth, Lower said. Shewanella probably represent one of the earliest forms of respiration. "These organisms may give us a glimpse of what life was like before oxygen existed," he told Discovery News. The work also opens up the tantalizing possibility that some day, scientists will be able to use Shewanella for remediation by, for example, engineering bacteria that produce more of their proteins and then dumping the microbes on contaminated sites. Get More NewsSpiders, Scorpions Among World's Oldest CreaturesMany creepy crawlies have been on Earth much longer than previously believed.Blood-Sucking Vampire Bats Sing DuetsWhite-winged vampire bats "harmonize" with separated roost mates.Oldest Hebrew Writing Possibly FoundAncient inscriptions on a 3,000-year-old pottery shard could make history.Rare, Prehistoric-Age Reptile Found in N.Z.A tuatara has been spotted on the New Zealand mainland for the first time in 200 years.Iceman Has No Living RelativesOetzi, the 5,300 year-old frozen mummy, left no living genetic legacy.SLIDE SHOW: Landscapes of TerrorWhat makes a place feel scary? There are scientific explanations.It's Official: People Are Warming the PolesHumans are conclusively to blame for polar warming, say scientists.Eight-Armed Animal Preceded DinosaursWhat may be one of Earth's first animals was no bigger than a coaster and had eight arms.Phoenicians Live on in People's GenesOne in 17 Mediterranean men may be descended from ancient Phoenicians.Pesticides, Fertilizers Linked to Frog DeclineA pesticide is found to promote parasites among amphibians.Hubble Telescope Taking Photos AgainThe Hubble Space Telescope is once again snapping stunning photos of the universe.Andean Mummy Hairs Show Hallucinogen UseScientists find direct evidence of hallucinogenic drug use among ancient Andeans.Opals on Mars Reveal Planet's Long Wet PastOpals found on Mars suggest the planet has been wet for much longer. |
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