The team used an innovative DNA test to catalog the bacteria in air samples taken from the Texas cities of San Antonio and Austin. Surprisingly, they found a widely varied bacterial population that rivals the diversity found in soil. They also found naturally occurring relatives of microbes that could be used in bioterrorist attacks -- although many of these relatives are harmless.
"Before this study, no one had a sense of the diversity of the microbes in the air," says lead author Gary Andersen of Berkeley Lab's Earth Sciences Division.
The research, which will be published this week in the online early edition of the Proceedings of the National Academy of Sciences, serves two purposes. It paves the way for regional bacterial censuses that will help a Department of Homeland Security bioterrorism surveillance program differentiate between normal and suspicious fluctuations in airborne pathogens. It will also help scientists establish a baseline of airborne microbes, which they can use to track how climate change affects bacterial populations.
"We want to determine the background levels of airborne pathogens and other microbes because only very limited work has been conducted on cataloging organisms in the air," says Andersen. "This work underscores how much we don't know about airborne bacterial populations, or where the bacteria come from."
In the past, scientists relied on bacterial cultures to determine what microbes are present in an air sample. In this method, the culture media is exposed to the sample, and whatever grows is counted. Unfortunately, this approach leaves out all of the organisms that can't survive i
Source:DOE/Lawrence Berkeley National Laboratory