Watch A Killer Cholera Bacteria Fish For New DNA Using A Tiny Spear

Gone fishing... for genetic material. Ankur Dalia, Indiana University

Bacteria have a sneaky weapon up their sleeves in the ongoing war with humans: the ability to snatch pieces of DNA from the surrounding environment and use it to evolve new traits rapidly, such as antibiotic resistance.

For the first time, biologists at Indiana University have imaged a cholera-causing bacteria performing this nifty little task. Essentially, it's like the bacteria shoots out a harpoon and reels the DNA fragments in, just like fishing.

Check it out in the video below.

The bacterium in question is Vibrio cholerae, the microbe that causes cholera, an infectious and deadly disease that infects millions of people each year. As reported in the journal Nature Microbiology, the video shows a pilus, an arm-like appendage over 10,000 times thinner than a human hair, fling out of a bacterium to catch DNA floating around. 

"It's like threading a needle," study first author Courtney Ellison explained in a statement. "The size of the hole in the outer membrane is almost the exact width of a DNA helix bent in half, which is likely what is coming across. If there weren't a pilus to guide it, the chance the DNA would hit the pore at just the right angle to pass into the cell is basically zero."

It was only possible to image this crafty maneuver thanks to technology recently developed by Indiana University that allows researchers to “paint” the bacterium's pilus and free-floating DNA fragments with special glowing dyes.

Scientists call this process "horizontal gene transfer", as opposed to the usual “vertical gene transfer” like you see between parents and their offspring. Using this transfer, it's possible to exchange genetic material between different species. Horizontal gene transfer can even transfer genetic material from bacteria to fungi, fungi to fungi, bacteria to plants, plant to plant, human to protozoan, and even bacteria to animal.

Generally speaking, this method of gene transfer has massively shaped the web of life. It works rapidly and therefore can result in evolutionary change quickly. It's one of the main ways in which many bacteria have evolved to become resistant to antibiotics so swiftly in the past few decades.

So, as you can imagine, the more we understand about it, the better. 

"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," added senior author Ankur Dalia, an assistant professor in the IU Bloomington College of Arts and Sciences' Department of Biology.

"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," he added.

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