Modern Bacteria Can Add DNA from Creatures Long-Dead to Its Own

From a bacteria’s perspective the environment is one big DNA waste yard. Researchers have now 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 itself.

Furthermore old DNA is not limited to only returning microbes to earlier states. Damaged DNA can also create new combinations of already functional sequences. You can compare it to a bunch of bacteria which poke around a trash pile looking for fragments they can use. Occasionally they hit some ‘second-hand gold’, which they can use right away. At other times they run the risk of cutting themselves up. It goes both ways. This discovery has a number of consequences partially because there is a potential risk for people when pathogen bacteria or multi-resistant bacteria exchange small fragments of ‘dangerous’ DNA e.g. at hospitals, in biological waste and in waste water.



In the grand perspective the bacteria’s uptake of short DNA represents a fundamental evolutionary process that only needs a growing cell consuming DNA pieces. A process that possibly is a kind of original type of gene-transfer or DNA-sharing between bacteria. The results show how genetic evolution can happen in jerks in small units. The meaning of this is great for our understanding of how microorganisms have exchanged genes through the history of life. The new results also support the theories about gene-transfer as a decisive factor in life’s early evolution.

Søren Overballe-Petersen explains: "This is one of the most exciting perspectives of our discovery. Computer simulations have shown that even early bacteria on Earth had the ability to share DNA – but it was hard to see how it could happen. Now we suggest how the first bacteria exchanged DNA. It is not even a mechanism developed to this specific purpose but rather as a common process, which is a consequence of living and dying."