For The First Time, Scientists Have Caught Bacteria “Fishing” For DNA From Their Dead Friends

Bacteria are slippery little suckers. They evolve rapidly, developing resistance to antibiotics and therefore becoming increasingly difficult to deal with. Now, for the first time, researchers have caught on film one of the mechanisms the microbes use for this speedy evolution.

Two Vibrio cholerae bacteria – the pathogen responsible for cholera – sit under a microscope, glowing a vivid green. As we watch, a tendril snakes forth from one of the bacterium, harpooning a piece of DNA and carrying it back to its body.

That appendage is called a pili, and the process whereby the bacteria incorporates the new genetic material from a different organism into its own DNA to expedite its evolution is called horizontal gene transfer.

And this is the first time scientists have directly observed a bacterium using a pilus to effect this gene transfer; it’s a mechanism that has been hypothesised for decades.

“Horizontal gene transfer is an important way that antibiotic resistance moves between bacterial species, but the process has never been observed before, since the structures involved are so incredibly small,” said biologist Ankur Dalia of Indiana University Bloomington.

“It’s important to understand this process, since the more we understand about how bacteria share DNA, the better our chances are of thwarting it.”

Exactly how bacteria used their pili to snare DNA remained elusive, partially because of the extremely small scales involved. A pilus is over 10,000 times thinner than a human hair, which means it’s very difficult to observe.

What the team did – and the reason those bacteria glow with an eerie green light – is develop a new method of painting both the pili and the DNA with fluorescent dye. When they stuck the whole kit and kaboodle under a microscope, they were able to see the process with their own eyes for the first time.

Watch the video and read more here or read the scientific paper published in Nature Microbiology