LSU scientist finds evidence of 'rain-making' bacteria

Could have implications for climate and understanding dissemination of agricultural pathogens

Brent Christner, LSU assistant professor of biological sciences, collecting precipitation samples in Antarctica. Click here for more information.

BATON ROUGE – Brent Christner, LSU professor of biological sciences, in partnership with colleagues in Montana and France, recently found evidence that rain-making bacteria are widely distributed in the atmosphere. These biological particles could factor heavily into the precipitation cycle, affecting climate, agricultural productivity and even global warming. Christner and his colleagues will publish their results in the prestigious journal “Science” on Feb. 29.

Christner’s team examined precipitation from global locations and demonstrated that the most active ice nuclei – a substrate that enhances the formation of ice – are biological in origin. This is important because the formation of ice in clouds is required for snow and most rainfall. Dust and soot particles can serve as ice nuclei, but biological ice nuclei are capable of catalyzing freezing at much warmer temperatures. If present in clouds, biological ice nuclei may affect the processes that trigger precipitation.

The concept of rain-making bacteria isn’t far-fetched. Cloud seeding with silver iodide or dry ice has been done for more than 60 years. Many ski resorts use a commercially available freeze-dried preparation of ice-nucleating bacteria to make snow when the temperature is just a few degrees below freezing.

“My colleague David Sands from Montana State University proposed the concept of ‘bioprecipitation’ over 25 years ago and few scientists took it seriously, but evidence is beginning to accumulate that supports this idea,” said Christner.