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Giant Bacterium Discovered

A single-celled microbe large enough to be seen with the naked eye has been found by researchers sampling ocean dredgings in the South Atlantic.

The bacterium - as big as the period at the end of this sentence - is the largest ever identified.

The microbe, discovered near Namibia, lives by absorbing sulfur and nitrates, and it swells as the chemicals are stored inside its cell walls, researchers report in a study published Friday in the journal Science.

The biggest of the bacteria is 0.75 millimeter, according to a report by Science.

Researchers at the Max Planck Institute for Marine Microbiology, who made the discovery, said the microbes form chain-like colonies that tend to glow from the absorbed nitrates.

"They look like a thin string of pearls," said the scientists, who named the new microbe Thiomargarita namibiensis, which means "Sulfur Pearl of Namibia."

"If the largest Thiomargarita was a blue whale," Science said in a statement, "then an ordinary bacterium would be a bit smaller than a newborn mouse."

In this analogy, the largest previously known bacterium "would be about as big as a lion," about 100 times smaller than Thiomargarita, Science reports. The previous record holder was Epulopiscum fishelsoni, a microbe found in the gut of surgeonfish.

Max Planck researchers said the bacteria live in an environment with high levels of hydrogen sulfide, conditions that are toxic to most other forms of life.

The scientists said Thiomargarita is found in great concentrations in Namibian coastal sediments that contain high levels of toxic sulfide.

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