Microorganisms Discovered in Middle and Upper Troposphere

The latest study published in the journal Proceedings of the National Academy of Sciences is the first to document the presence of microorganisms in the middle and upper troposphere.

Large amounts of bacteria found four to six miles above the Earth's surface interest the atmospheric scientists, as these microorganisms could play an influential role in the formation of clouds and may also have the potential to alter weather and climatic conditions. The bacteria traversing such great distances could be used for disease transmission models.

Researchers from the Georgia Institute of Technology took air samples using a filter system onboard a NASA DC-8 jet that were taken as part of NASA's Genesis and Rapid Intensification Processes (GRIP) program which aimed at studying low and high altitude air masses that were connected with tropical storms. The sampling was done over land and ocean, including the Caribbean Sea and parts of the Atlantic Ocean. The sampling was done before, during and after hurricanes Earl and Karl in 2010.

"We did not expect to find so many microorganisms in the troposphere, which is considered a difficult environment for life," Kostas Konstantinidis, an assistant professor in the School of Civil and Environmental Engineering at the Georgia Institute of Technology said in a press statement. "There seems to be quite a diversity of species, but not all bacteria make it into the upper troposphere."

On analyzing the filter samples using genomic techniques that included polymerase chain reaction (PCR) and gene sequencing, they noticed that most of the microorganism were marine bacteria and the air samples over land had territorial bacteria. Bacteria were found in abundance when compared to fungi.

According to the researchers, hurricanes had a significant impact on the distribution and dynamics of microorganism populations.

According to Athanasios Nenes, a professor in the Georgia Tech School of Earth and Atmospheric Sciences and School of Chemical and Biomolecular Engineering, lack of dust and other materials and the presence of a small number of microorganisms boosts the formation of ice at such an altitude. And if they help in the formation of ice, they could affect the surrounding clouds.

Further studies are required to know what sort of bacteria survive these altitudes and also the role these microorganisms play. Researchers plan on investigating whether any metabolic functions are being carried out by these microorganisms in the troposphere.