Source: NIH

Researchers from Indiana University have managed to capture real-time video of a bacterium reaching out to grab a fragment of cell free DNA for the first time. Their work, which was detailed in Nature Microbiology last month, shows a Vibrio cholerae cell stretching out a pilus to pull in a DNA fragment (shown in red). When the pilus connects with the DNA, it is rapidly withdrawn into the cell and the DNA is threaded through a pore to be incorporated in the bacterial genome.

Horizontal gene transfer has been known about in bacteria for a long time, but this is the first time that researchers have been able to record the mechanism in real-time and in such impressive detail. The driving force behind this incredible activity is that, unlike humans and many other organisms, bacteria reproduce asexually via cell division. Because of this, each new generation will have DNA that is identical to the parent and so they need to have a mechanism that allows them to increase genetic diversity.

The mechanism shown in the new video is one of the ways in which bacteria can do this, harvesting new DNA from the environment around them.

The video, which is the result of a collaboration between researchers at Indiana University, Bloomington and Brooklyn College, was captured by switching out one of the natural amino acids in the pilus fibre with cysteine. The new amino acid could then be tagged with fluorescent dyes that selectively bind to cysteine molecules, allowing the researchers to capture this incredible footage.  

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