Evolution of hyperswarming bacteria could develop anti-biofilm therapies

August 15, 2013
Credit: Cell Reports, van Ditmarsch et al.

The evolution of hyperswarming, pathogenic bacteria might sound like the plot of a horror film, but such bugs really have repeatedly evolved in a lab, and the good news is that they should be less of a problem to us than their less mobile kin. That's because those hyperswarmers, adorned with multiple whipping flagella, are also much worse at sticking together on surfaces in hard-to-treat biofilms. They might even help us figure out a way to develop anti-biofilm therapies for use in people with cystic fibrosis or other conditions, say researchers who report their findings in Cell Reports on August 15th.

The findings are also a textbook example of real-time experimental evolution. What's more, says Joao Xavier of Memorial Sloan Kettering Cancer Center, they are a "unique example of strikingly parallel ."

In other words, the evolution that he and his team witnessed was repeatable, all the way down to the molecular level.

The researchers didn't set out with the goal to evolve hyperswarmers, but they did passage Pseudomonas aeruginosa on special plates over a period of days. On those plates, bacteria that could spread out had an advantage in harvesting nutrients from the surface, and within a matter of days, some of those bacteria started hyperswarming.

Credit: Cell Reports, van Ditmarsch et al.

Investigation of the bacteria showed that P. aeruginosa gained its hyperswarming ability through a single in a flagellar synthesis regulator (FleN). As a result, the bacteria, which usually have one single flagellum, were locked into a multi-flagellated state. They became better at moving around to cover a surface, but much worse at forming densely packed, surface-attached biofilm communities. All told, the researchers saw this new ability independently arise 20 times.

"The fact that the molecular adaptations were the same in independent lineages suggests evolution may be, to some extent, predictable," says Xavier.

This video is not supported by your browser at this time.
Part 1: Swarming by the ancestral (wild type) strain, Pseudomonas aeruginosa PA14, shows the typical branching pattern of swarming colonies. Part 2: Swarming by a hyperswarmer mutant, clone #10, shows a very distinct phenotype without branching. Part 3: Repulsion assay for hyperswarmer clone #5 shows that the colony is still repelled by the presence of a immotile strain (flgK-), although less than the wild type or other hyperswarmer clones. Credit: Cell Reports, van Ditmarsch et al.

The findings may be very important because biofilms are a major problem in clinical settings. Infectious biofilms are hard to remove and difficult to kill with antibiotics. Drugs that target FleN or that otherwise make bacteria better at spreading out and worse at settling down could leave them more vulnerable to antibiotics and easier to get rid of.

Explore further: Viruses help scientists battle pathogenic bacteria and improve water supply

More information: Cell Reports, van Ditmarsch et al.: "Convergent evolution of hyperswarming leads to impaired biofilm formation in pathogenic bacteria." dx.doi.org/10.1016/j.celrep.2013.07.026

Related Stories

Study reveals secrets of bacterial slime

April 12, 2013

(Phys.org) —Newcastle University scientists have revealed the mechanism that causes a slime to form, making bacteria hard to shift and resistant to antibiotics.

Bacteria in drinking water are key to keeping it clean

August 14, 2013

Research at the University of Sheffield, published in the latest issue of Water Science and Technology: Water Supply, points the way to more sophisticated and targeted methods of ensuring our drinking water remains safe to ...

Recommended for you

Researchers design first artificial ribosome

July 29, 2015

Researchers at the University of Illinois at Chicago and Northwestern University have engineered a tethered ribosome that works nearly as well as the authentic cellular component, or organelle, that produces all the proteins ...

Studies reveal details of error correction in cell division

July 29, 2015

Cell biologists led by Thomas Maresca at the University of Massachusetts Amherst, with collaborators elsewhere, report an advance in understanding the workings of an error correction mechanism that helps cells detect and ...

Researchers discover new type of mycovirus

July 29, 2015

Researchers, led by Dr Robert Coutts, Leverhulme Research Fellow from the School of Life and Medical Sciences at the University of Hertfordshire, and Dr Ioly Kotta-Loizou, Research Associate at Imperial College, have discovered ...

Stressed out plants send animal-like signals

July 29, 2015

University of Adelaide research has shown for the first time that, despite not having a nervous system, plants use signals normally associated with animals when they encounter stress.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.