Super-resolution microscopy observes previously unknown arrangement of bacterial plasmids

Researchers at the University of Arkansas (Fayetteville, AK) and collaborators used super-resolution microscopy to observe a previously unknown arrangement of bacterial plasmids—small, circular DNA molecules that commonly carry genes responsible for antibiotic resistance.

The discovery sheds light on how bacteria maintain plasmids of which the bacteria make many copies, explains Yong Wang, assistant professor of physics at the University of Arkansas and co-author of the study. For the bacteria to maintain their antibiotic resistance, he says, they need to maintain these plasmids—so knowing more about how the plasmids are maintained could lead to potential way to interfere with the resistance to antibiotics.

Wang collaborated with two colleagues at the University of Toronto (Canada), where he was a postdoctoral research fellow before he joined the University of Arkansas faculty in January 2016. The team combined quantitative super-resolved fluorescence microscopy, which improves the spatial resolution of optical microscopy from 200 nm to 10–20 nm, with single-molecule fluorescence techniques and statistical physics/modeling.

With their approach, the research team observed that the plasmids were arranged into two populations. Some plasmids formed large clusters, while the majority of plasmids were randomly distributed in the bacteria. Now, Wang says that he and his students are exploring the origins, as well as the temporal evolution, of the observed arrangement of plasmids.

Full details of the work appear in the Biophysical Journal; for more information, please visit http://dx.doi.org/10.1016/j.bpj.2016.06.033.