Snowflakes carry a core of bacteria

Those beautiful snowflakes drifting out of the sky may have a surprise inside – bacteria.

Atmospheric scientists have long known that under most conditions moisture needs something to cling to in order to condense into snow and rain. A study published Friday in the journal Science shows a large share of those so-called nucleators turn out to be bacteria that can affect plants.

“Bacteria are by far the most active ice nuclei in nature,” said Brent C. Christner, an assistant professor of biological sciences at Louisiana State University.

Christner and colleagues sampled snow from Antarctica, France, Montana and Canada’s Yukon and found that as much as 85% of the nuclei were bacteria, he said. The bacteria finding was most common in France, followed by Montana and the Yukon, and was even present in Antarctica.

The most common bacteria found were Pseudomonas syringae, which can cause disease in several types of plants including tomatoes and beans.

In the past, scientists have tried to eliminate Pseudomonas, Christner said, but now that it turns out to be a major factor in encouraging snow and rain, he wonders if that is a good idea. Eliminating the bacteria might result in less rain or snow, or it might be replaced by other nuclei such as soot and dust.