91av

A “LAZARUS” bacterium which thrived millions of years before dinosaurs walked
the Earth has been brought back to life. Biologists are astonished that the
250-million-year-old bug could be revived, suggesting that if conditions are
right, bacterial spores might survive indefinitely.

It also adds weight to the controversial notion that life was scattered
throughout the cosmos by comets. The theory, put forward in 1981 by astronomer
Fred Hoyle, suggests that comets “seeded” life on Earth.

Provisionally named Bacillus permians to denote the geological
period from which it originates, the born-again bacterium is unknown to science.
“It is alive and, to the best of anyone’s knowledge, there’s no other organism
that’s been around that long,” says Russell Vreeland, the scientist who isolated
the bacterium. Its nearest “ancient” rivals are bacterial babes by comparison,
just 25 to 40 million years old
(91av, 17 May 1997, p 7).

Vreeland and his colleagues at West Chester University in Pennsylvania
isolated the ancient bacterium from the Salado salt formation at Carlsbad, New
Mexico, an underground cavern used for storing nuclear waste. While the salt
crystals were forming 250 million years ago, bacterial spores in a drop of water
became trapped in a cavity in the salt—a feature known as an inclusion.
“The inclusion looks like a cube within a cube,” says Vreeland. Geologists dated
the layer where the crystal was found—560 metres down in a shaft leading
to the repository—at 250 million years old.

Under scrupulously sterile conditions, Vreeland liberated the spores from
their hibernation. He extracted the 3-microlitre inclusion and squirted it onto
growth medium. The spores grew into familiar rod-shaped bacillus bacteria. “I
think the cell wall is a little thicker than in normal bacillus bacteria,” he
says. Vreeland is now comparing the genes of the ancient bug with those of two
contemporary relatives: Bacillus marismortui, from the Dead Sea, and
Virgibacillus pantothenticus.

John Parkes, a geomicrobiologist at the University of Bristol, says that
survival of such ancient spores is astonishing. “All the laws of chemistry tell
you that the complex molecules in the spores should have degraded to very simple
compounds such as carbon dioxide,” he says.

Parkes says that before people start jumping to conclusions, they should wait
until someone else finds similar bacteria from the same salt formation. But if
it is proven that spores can survive this long, he wonders, why should they die
at all? “Where else are these dormant organisms waiting to be reawakened?”