Bacteria can gain novel traits, like antibiotic resistance, by sharing DNA with one another through processes cumulatively termed horizontal gene transfer.
One major mechanism of horizontal gene transfer is called natural transformation, a process by which a bacterium can take up free DNA from the environment and then integrate that DNA into its genome. Bacteria take up DNA from the environment using long hair-like surface appendages called pili (see “DNA-reeling bacteria yield new insight on how superbugs acquire drug resistance” and “IU scientists watch bacteria 'harpoon' DNA to speed their evolution”).
In a new study, published in the journal Cell, IU researchers focus on characterizing how bacteria can integrate this DNA into their genome after taking it up from the environment. This work was led by Ankur Dalia, an assistant professor in the Indiana University College of Arts and Sciences' Department of Biology.
Attempting to better understand DNA integration, the Dalia lab developed new methods to directly observe this process in real time in single bacterial cells under the microscope. Specifically, they developed a number of fluorescent "reporters" to tell exactly (1) when cells were trying to integrate DNA (see Video 1), (2) when cells succeeded at integrating this DNA, and (3) when the new DNA that they integrated was expressed during the process.