‘Broadband’ Networks of Viruses May Help Bacteria Evolve Faster

Bacteria have a sneaky evolutionary advantage: their own version of the internet for swapping survival solutions. It’s a living network of viruses that can shuttle genetic information between unrelated cells. Known as transduction, this process is one of the ways that bacteria can bypass the generation-by-generation plodding of vertical inheritance and instead share information horizontally, enabling genes slowly shaped by natural selection to enter a new population in an instant.
Scientists have known this transduction network must influence bacterial evolution across the sweep of centuries, but they presumed its short-term impact might be limited because transduction events seemed rare. A study published last week in Science, however, discovered a new mechanism of transduction that occurs 1,000 times more often, and that may accelerate bacterial evolution to a similar degree. Transduction may in fact be a central force in bacterial evolution.

“We had assumed that transduction occurred at rates analogous to dial-up internet,” said John Chen, an assistant professor of microbiology and immunology at the National University of Singapore and a lead co-author on this study. “But it appears that in some cases, transduction rates are more akin to broadband.” Their results not only suggest that transduction makes horizontal gene transfer much more common, but also that this bacterial internet might have been shaped by selection for the benefit of both bacteria and the viruses called bacteriophages.

A bacteriophage resembles a lunar landing module crossed with a spider, like something out of an arachnophobic astronaut’s nightmare. It lands on a bacterium, pierces the cell membrane and injects its DNA into the cell. From there, the virus hijacks the host’s cellular machinery to make copies of itself, which then bust out of the cell to infect other bacteria. On rare occasions, bits of bacterial DNA get packaged in the phage capsules instead and get added to the genomes of subsequently infected bacteria. This genetic transfer is known as general transduction

Read More:https://www.quantamagazine.org/broadband-networks-of-viruses-may-help-bacteria-evolve-faster-20181016/