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Bacteria can grow, travel in clouds
UPI, Tue 9 Jan 2001

A team of Austrian scientists has discovered
What they say is the first evidence
That bacteria can not only exist
But can also grow and reproduce in cloud water.

Brigit Sattler of the University of Innsbruck and colleagues are now trying to characterize the bacteria, but Sattler told United Press International she "can't exclude" the possibility these bacteria may cause disease.

The Austrian team found the bacteria in cloud droplets at altitudes of approximately 10,000 feet (3,100 meters), and at temperatures between 14 and 32 degrees Fahrenheit (minus 10 and 0 degrees Celsius).

The findings will be reported in the January 15 issue of Geophysical Research Letters, published by the American Geophysical Union in Washington. Sattler is just "It could be possible they are pathogenic. But the fact is that bacteria from the ground and water can be brought into the atmosphere by wind or sea spray, " she said.

Researchers have long known that air currents can carry bacteria, but scientists were never certain if they were actually active and capable of reproducing in the air. At least some of the bacteria are specialized to survive in the cold -- some are found in snow, for example. Sattler said she wants to find out the mechanisms the bacteria use to survive in such an environment and to learn more about their metabolism as well as their role in that environment.

One of the researchers, Hans Puxbaum, an atmospheric chemist at the Technical University of Vienna, noted the bacteria stop reproducing when the temperature reaches around 60 degrees Fahrenheit (15 degrees Celsius). Puxbaum also said the bacteria may well play a role in the weather formation, acting as nuclei around which water can freeze and fall to Earth as snow or ice.

The research team became interested in looking for bacteria in such an inhospitable environment after analyzing snow in alpine glaciers, added Puxbaum. In those studies, the scientists found hydrocarbons whose presence could not be explained by man-made or atmospheric processes, but instead were characteristic of bacteria. (Reported by Harvey Black in Madison, Wisc.) --