NEW BRUNSWICK, N.J. — Airborne bacteria can travel thousands of miles all over the world, according to a new study by Rutgers researchers and other scientists. This finding refutes a previous belief made by experts in this area, which posited that bacteria latches onto people and animals, and spreads around the world in that fashion.
This new theory, called the “air bridge” hypothesis, sheds light on how pathogenic bacteria spread and share antibiotic-resistant genes.
“Our research suggests that there must be a planet-wide mechanism that ensures the exchange of bacteria between faraway places,” says senior author Konstantin Severinov, a professor of molecular biology and biochemistry in the School of Arts and Sciences at Rutgers, in a media release. “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.”
Severinov and his team say that bacterial cells infected by viruses have what they refer to as “molecular memories” stored in special regions of bacterial DNA. The cells that survive viral infections pass the memories to their offspring as small bits of viral DNA. By examining the order of these memories, scientists can trace the history of bacterial interactions with viruses over time.
For their study, they collected the bacteria Thermus thermophilus from hot gravel on Mount Vesuvius and hot springs on Mount Etna in Italy. They also used bacteria from several other locations around the world in South America and Northern Asia.
The authors predicted that bacteria of the same species living in these hot springs from different parts of the world would have unique molecular memories of their own encounters with viruses. They figured that bacteria would continue to evolve rapidly, but into different species.
“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,” explains 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.”
Moving forward, Sevrinov hopes to test the air bridge hypothesis by sampling air at different altitudes and locations around the world, then identifying the bacteria there — and their memories.
The study was published in Philosophical Transactions of the Royal Society B.