incorporating old DNA

Bacteria incorporate pieces of old DNA in their own genome, scientists discover

What DNA fragments --- some thousands of years old --- from biological waste and wastewater have hospital bacteria incorporated?

November 19, 2013

Illustration of bacteria that take up DNA fragments from their surroundings. Some of the grasped DNA fragments attach to the bacteria’s own DNA and are incorporated. (Credit: Katrine Harving Holm).

From a bacteria’s perspective, the environment is one big DNA waste yard. Now researchers from Denmark and Norway have shown that bacteria can take up small as well as large pieces of old DNA from this scrapheap and include it in their own genome.

This discovery may have major consequences both in connection with resistance to antibiotics in hospitals and in our perception of the evolution of life itself.

Our surroundings contain large amounts of strongly fragmented and damaged DNA, which is being degraded. Some of it may be thousands of years old.

Laboratory experiments with microbes and various kinds of DNA have shown that bacteria take up very short and damaged DNA from the environment and passively integrate it in their own genome.

Furthermore, this mechanism has also been shown to work with a modern bacteria’s uptake of 43.000 years old mammoth DNA.

The results were just published in Proceedings of the National Academy of Sciences (open access).