Some microorganisms form resistant structures called spores when exposed to adverse conditions.  These spores have been found to survive for hundreds and even thousands of years under the proper conditions.  Researchers now believe they have isolated halophilic (salt-loving) bacteria spores that were trapped in brine "bubbles" as the salt in the ancient sea evaporated and formed the bedded evaporite formation from which WIPP was mined.  If true, these organisms are the oldest ever discovered (220-250 million years old).  The previous "record" was from the mid-1990s with detection of bacterial spores in a bee preserved in amber 25–40 million years old*.

Intact salt crystals were carefully collected from the walls of WIPP's air intake shaft at a depth of 569 meters (1867 feet) below the surface.  The nearly pure salt crystals contained fluid inclusions (tiny openings inside the crystals that contain a mixture of saturated brine and nitrogen).  After thoroughly sterilizing the surface of the crystals, researchers drilled into and removed fluid from a tiny inclusion (less than 10 microlitres).  The fluid was then inoculated into a growth medium under carefully controlled conditions.  The new bacteria then grew from these spores, and complete gene sequences of the 16S ribosomal DNA subsequently showed that the organism is related to present-day species as part of the lineage of Bacillus marismortui. 

Drs. Russell Vreeland and William Rosenzweig of West Chester University, Pennsylvania, and Dr. Dennis Powers, a Consulting Geologist in Anthony, Texas published a paper in the October 19, 2000 issue of the journal Nature.  Their research continues to study the new organism and compare it with its present-day relatives.

Visit the researcher's home page at West Chester University.

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* Cano, R. J. & Borucki, M. Revival and identification of bacterial spores in 25 to 40 million year old Dominican amber. Science 268, 1060-1064 (1995).