A team of researchers claims to have been able to film for the first time a bacterium “fishing” the DNA of a dead bacterium. A mechanism that allows – among other things – to transmit their resistance capacity to antibiotics.
This little film is unpublished. Incredible in itself, it could also in the future save many lives. Two Vibrio cholerae (cholera) bacteria are on the table, colored to better visualize them. One of them is alive, the other is dead. The first penetrates the other with an appendix (pilus) and retrieves a piece of DNA of the deceased and integrates it into his own body. This is called horizontal gene transfer. Theorized, but never directly observed, the process has finally been filmed. And that could greatly serve us. The details of the study are published in the journal Nature Microbiology.
A structure 10,000 times thinner than a human hair
“Horizontal gene transfer allows antibiotic resistance to move between bacterial species, but the process has never been observed before, because the structures involved are incredibly small,” says Indiana University biologist Ankur Dalia, lead author of the study. It is important to understand this process because the more we understand how bacteria share DNA, the better our chances of counteracting them. ”
To observe this pilus in action – a kind of bacterial fishing rod 10,000 times thinner than a human hair – researchers say they used a fluorescent dye. Only by isolating the two bacteria was it then possible to observe the first “use” in the second. And the process is incredibly accurate. “It’s like putting on a needle,” says biologist Courtney Ellison, co-author of the study. The size of the hole in the outer membrane is almost identical to the width of a DNA helix bent in half. If there were no pilus to guide him, it would be impossible for the piece of DNA to integrate in the right angle to pass into the second cell.
Thus, when a bacterium dies, it opens and releases its DNA. This microbial appendage then makes it possible to capture pieces of this DNA. If the defunct bacteria had “learned” to resist antibiotics, then this resistance to treatment would be transferred to the “robber” bacterium, which itself will pass it on to its own offspring. This is how antibiotic resistance is spreading, to the point of representing a real danger to human health.
The super-resistant bacteria could indeed kill up to 10 million people a year by 2050, almost as much as cancer, revealed a few weeks ago a study. By optimally apprehending the mechanisms used by these organizations to propagate these resistance to treatment, the researchers put the odds on their side to counter the phenomenon. One step ahead that could save millions of lives in the future.