A new study is providing evidence that bacteria can fly thousands of miles through the air without depending on people and animals for transport. According to the experts, their new “air bridge” theory may explain how harmful bacteria have the same antibiotic resistance genes in common.
Study senior author Konstantin Severinov is a principal investigator at the Waksman Institute of Microbiology and a professor of Molecular Biology at Rutgers University.
“Our research suggests that there must be a planet-wide mechanism that ensures the exchange of bacteria between faraway places,” said Professor Severinov. “Because the bacteria we study live in very hot water – about 160 degrees Fahrenheit – in remote places, it is not feasible to imagine that animals, birds or humans transport them. They must be transported by air and this movement must be very extensive so bacteria in isolated places share common characteristics.”
The investigation was focused on “molecular memories” that are stored in bacterial DNA, providing a record of when the bacteria encountered viruses. Bacteriophages, which are viruses that infect bacteria, can be found everywhere on the planet that bacteria exist and have a profound influence on microbial populations.
The scientists collected Thermus thermophilus bacteria in hot gravel on Mount Vesuvius and from hot springs in Italy, Chile, and Russia.
After bacterial cells are infected by viruses, they store molecular memories in special regions of bacterial DNA called CRISPR arrays. Cells that survive infections pass the memories as small pieces of viral DNA to their offspring. Scientists can trace the history of the bacterial interaction with viruses by looking at the chronological order of the memories.
The scientists expected that bacteria collected in hot springs thousands of miles apart would have very different memories of virus encounters, even though they were the same species. The scientists also thought that the bacteria would have evolved independently of each other, rapidly becoming very different.
“What we found, however, is that there were plenty of shared memories – identical pieces of viral DNA stored in the same order in the DNA of bacteria from distant hot springs,” explained Professor Severinov. “Our analysis may inform ecological and epidemiological studies of harmful bacteria that globally share antibiotic resistance genes and may also get dispersed by air instead of human travelers.”
Next, the researchers plan to test their air bridge hypothesis by identifying bacteria present in the air at different altitudes and locations around the world.
The study is published in the journal Philosophical Transactions of the Royal Society B.
Image Credit: Yaroslav Ispolatov