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KNOXVILLE – Research by a University of Tennessee scientist shows that tiny bacteria that help regulate greenhouse gases survive best in specific water temperatures, a finding with significant implications in the face of global climate change.

The research, conducted by UT assistant professor Erik Zinser, along with colleagues from the Massachusetts Institute of Technology and the University of Hawaii, appeared in the March 24 issue of the journal Science.

Scientists from the team traveled via ship from the United Kingdom to the Falkland Islands in the South Atlantic, taking measurements along the way of a group of bacteria, called Prochlorococcus.

“We wanted to see how the populations of the bacteria might differ at different latitudes, depths and hemispheres,” said Zinser, an assistant professor of microbiology. “The goal was to understand what variables might influence those populations, if at all.”

The team used a molecular process, known as polymerase chain reaction, to determine how many of each type of the bacteria they were finding in different locations. By comparing these amounts to the environments along the ship’s path, Zinser and his colleagues found that water temperature seemed to influence which type of the bacteria was dominant.

The bacteria are photosynthetic, meaning they use the sun’s energy to convert carbon dioxide into oxygen. In doing so, they help control the amount of CO2 in the atmosphere. If they are affected negatively by increasing water temperatures, then they may be less able to regulate the amount of CO2, which could drive the global warming process even further.

They are not found more than 40 degrees north or south of the equator, thriving closer to the equator in warmer waters, said Zinser. They found, though, that near the 40-degree border, a different type of the Prochlorococcus bacteria became dominant.

“At these higher latitudes, the water temperature was lower, and we found that temperature correlated well with which type was dominating,” said Zinser.

After the trip through the Atlantic, the scientists tested their observations in the lab to see if the bacteria found in the warmer waters grew better at higher temperatures and vice-versa. Their analysis showed that different types of bacteria did seem suited for certain temperatures.

“When you put the observations in the ocean together with the lab experiments, the results show that the two dominant groups may have evolved different ideal temperatures in order to thrive in different regions of the ocean,” said Zinser.

He said that the fact that temperature could have such a significant effect on these bacteria is especially relevant in light of their role in controlling the level of carbon dioxide.

Zinser said that more research will be required to examine how these emerging global changes may influence the bacteria in the future.



Jay Mayfield, media relations (865-974-9409, jay.mayfield@tennessee.edu)