Can bacteria release free DNA into their environment?

Question

[Natural transformation AKA natural competence](https://en.wikipedia.org/wiki/Transformation_%28genetics%29#Natural_transformation) involves the uptake of DNA into a competent bacterium (for horizontal gene transfer or as a food source). My question is about where this extracellular DNA can come from. Typically this "free" DNA originates from lysed bacterial cells. Are there instances where DNA is released *without* lysis that other bacteria can uptake via natural transformation? *Note:* I am not interested in [bacterial conjugation](https://en.wikipedia.org/wiki/Bacterial_conjugation) because I'm specifically interested in extracellular DNA that can be internalised by competent bacteria.

Answer 1

Yes, bacteria can release DNA into their environment without actually bursting open or dying.

While mostly it is believed that extracellular DNA comes from lysed (broken-open) bacterial cells, which is definitely common. However, some bacteria can actively release DNA through more controlled processes.

One example is the release of small membrane vesicles. These are tiny bubble-like structures released by bacteria that can carry DNA, proteins, and other molecules into the environment. The DNA inside these vesicles can later be taken up by other competent bacteria.

Bacteria also release extracellular DNA during biofilm formation. Biofilms are communities of bacteria that stick to surfaces, and the released DNA helps hold the biofilm together almost like a biological “glue.” At the same time, nearby bacteria may take up some of this DNA through natural transformation.

Another interesting example occurs in species like Streptococcus pneumoniae. Some bacteria become competent and release enzymes that lyse neighboring cells, freeing DNA into the environment while the competent cells themselves remain alive and able to absorb that DNA.

So, extracellular DNA is not always just a byproduct of dead bacteria. In many cases, bacteria actively contribute DNA to their surroundings as part of communication, adaptation, and horizontal gene transfer.

An easy way to think about it:

Sometimes bacteria share DNA intentionally, rather than only releasing it when they die.