Study: Snow, rain loaded with sky-high bacteria


Catching snowflakes on the tongue might never be the same.

Research being published tomorrow in Science magazine finds that snow and rain may form mostly on bacteria in the clouds — germs that attack tomatoes, green beans and other plants.

In some samples, as much as 85% of the ice nuclei were Pseudomonas syringae bacteria (photo), which cause plant diseases, microbiologist Brent Christner at Louisiana State University told the Associated Press.

His team sampled snow from Antarctica, France, Montana and the Yukon. The study found the bacteria in 20 samples of snow from around the world and subsequent research has also found it in summer rainfall in Louisiana.

Where are the bacteria most common? France, followed by Montana, the Yukon and Antarctica, though to a lesser degree.

Christner offered a caution about the origins of the microbes: "Just because we find an ice nucleator in rain or snow doesn't mean it originated in a cloud; it could be scavenged during precipitation."

Scientists have sought ways to eliminate this bacterium. Now they wonder about the effect of achieving that goal. Would there be less rain or snow, or would soot and dust be the major generators of precipitation?

"The question is, are they a good guy or a bad guy," Christner said, "and I don't have the answer to that."

Read more about the empirical evidence at Scientific American and LiveScience.


(Photo of downtown Oswego, N.Y., by Gary Walts, The Post-Standard, via AP)

Posted by Michael Winter at 06:13 PM/ET, February 28, 2008 in Health/Science, Research | Permalin