Even remote bacterial species around the globe share genetic material – including genes that lead to antibiotic-resistant bacteria – but how is this possible? Researchers at Rutgers University have a compelling new hypothesis.
A Rutgers University study suggests that microbes use natural currents as “air bridges,” allowing them to travel around the world. This “air bridge” hypothesis provides critical insight as to how bacteria, including antibiotic-resistant bacteria varieties, share genetic material. Currently, more than two million people annually become infected with antibiotic-resistant bacteria, a condition that is difficult, if not impossible, to treat.1
The Rutgers University study, led by researcher Konstantin Severinov, studied the “molecular memories” of bacteria after viral encounters, since the resulting memories would then be stored in bacterial DNA. As reported in Philosophical Transactions of the Royal Society B, the research team collected heated Thermus thermophilus bacteria from remote hot springs in three global locations: Italy, Chile and Russia.
In virus-infected bacterial cells (bacteriophages), molecular memories remain within special areas of bacterial DNA known as CRISPR arrays. Cells that survive infections pass these memories – small pieces of viral DNA – to offspring. The sequence of these memories permits researchers to review the history of bacterial-viral interactions.
The Rutgers researchers initially assumed that bacteria from the same species living thousands of miles apart would have different memories of viral encounters. Instead, says Severinov, “there were plenty of shared memories – identical species of viral DNA stored in the same order in the DNA of bacteria from distant hot springs.” As a result, the scientists have proposed a global bacterial exchange via an “air bridge” to explain this commonality – a hypothesis that may “also inform ecological and epidemiological studies of harmful bacteria that globally share antibiotic resistant genes and may also get dispersed by air instead of human travelers,” adds Severinov.
“Since the bacteria we study live in very hot water – 71 degrees Celsius – in remote places, it is not feasible to imagine that animals, birds or humans transport them,” Severinov explained. “They must be transported by air, and this movement must be very extensive so bacteria in isolated places share common characteristics.”
To obtain further evidence for the research team’s “air bridge” hypothesis, the researchers’ next steps include acquiring global air samples at different altitudes and identifying bacterial species there, including the molecular memories of these bacteria. Planes, drones and research balloons will need to be accessed.