Bacterial find supports theory life fell to Earth

Records have been smashed on what ranks as the oldest living creature yet discovered. US researchers have revived bacteria that spent the past 250 million years in suspended animation, trapped in a lump of rock salt.

The remarkable find adds weight to theories that life literally fell to Earth after drifting across space for uncounted millions of years.

It raises questions about where else ancient bacterial life might be lurking on this planet. It enhances the possibility that perhaps Mars or even the moon might harbour dormant bacteria.

The previous "oldest living creature" record was also held by a bacterium, a strain of Bacillus sphaericus. It was isolated from an extinct bee that was trapped in 2530 million-year-old amber.

The new find is also a strain of Bacillus, with DNA analysis showing it to be a relative of B. marisomortui, another salt-loving bacterium that plies the brackish waters of the Dead Sea.

The new bacteria were found by Dr Russell Vreeland of West Chester University, Pennsylvania, and colleagues. His findings are published this morning in the journal Nature.

The bacteria's survival can be attributed to the fact that they existed in a dormant state, a totally inactive yet viable form known as a bacterial spore. When under serious environmental pressure - for example trapped in an evaporating salt pan in increasingly salty conditions - some bacteria, including Bacillus, can produce spores. Once better conditions return they regenerate into their normal bacterial form.

Bacterial spores have been recovered from a 118-year-old can of meat, and a yeast has been cultured from a 166-year-old bottle of porter, writes geomicrobiologist, Dr John Parkes of Bristol University in an accompanying news-and-views report. Once revived, this same yeast was used to reproduce the original beer.

This new Bacillus species, so far designated B 2-9-3, was retrieved from a salt deposit in Texas, from a depth of 569 metres. The theory goes that this salt-tolerant bacterium became trapped in an evaporating salt water pool and formed spores.

If bacteria are tough enough to survive this kind of rough treatment over so long a time then perhaps the old "panspermia" theories have something in them. They hold that life began somewhere out there in space and then was distributed out across the universe. This "seeded" any planets hospitable enough to support bacterial life and of course what better location than the nice warm, salty, mineral-rich seas of the early Earth.

The search is now on to identify and revive even older bacteria. Who knows, maybe you have been sprinkling ancient bacteria over your spuds and carrots all these years and didn't even realise it?