This is the VOA Special English SCIENCE REPORT.
American scientists have reported finding the oldest living organism. The scientists say the organism - a bacterium - is two-hundred-fifty- million years old. They say it lived long before ancient creatures called dinosaurs appeared.
Russell Vreeland of West Chester University in Pennsylvania and his team announced the discovery. The publication Nature reported their findings.
Professor Vreeland and his team discovered the bacterium in the southwestern United States. They found it near Carlsbad, New Mexico, in an ancient piece of salt. The salt crystal came from a thick underground rock formation. Ancient remains and radiation show that the rock formation is two-hundred-fifty-million years old.
The scientists suggest the area was a large salt lake millions of years ago. The organism was found in a tiny amount of fluid inside a salt crystal. The scientists believe the bacterium was trapped inside the crystal and survived until the present. They believe the bacterium formed a spore in the salt crystal. A spore is an extremely small structure that can grow into an organism. Spores are well known for their long lives. In recent years, scientists have found living bacteria in a can of meat one-hundred-eighteen years old. They found a kind of yeast, or fungus in a bottle of ale more than one-hundred-sixty years old. Scientists even have found bacterial spores in an insect trapped in a piece of amber. The insect was estimated to be at least twenty-five-million years old.
However, some scientists have disputed claims of ancient bacteria discoveries. They suggested the way the bacteria were treated influenced the findings. The American scientists say they used extreme care to clean the surface of the salt crystal. They removed the fluid from inside the crystal. When the fluid was mixed with nutrients, the bacterium appeared.
Professor Vreeland says the bacterium is about two times older than the oldest reported organism. He says tests showed no sign of it being harmful or a cause of disease. The tests showed the bacterium belongs to a common group of bacteria found in soil, water and dust.
Some scientists say the age of the bacterium supports the idea that organisms can survive long enough to travel between planets on meteorites.
This VOA Special English SCIENCE REPORT was written by George Grow.