Evolution of hyperswarming bacteria could develop anti-biofilm therapies

Aug 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: How steroid hormones enable plants to grow

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

add to favorites email to friend print save as pdf

Related Stories

Study reveals secrets of bacterial slime

Apr 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

Aug 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 t ...

Recommended for you

Researchers discover new strategy germs use to invade cells

4 hours ago

The hospital germ Pseudomonas aeruginosa wraps itself into the membrane of human cells: A team led by Dr. Thorsten Eierhoff and Junior Professor Dr. Winfried Römer from the Institute of Biology II, members of the Cluster ...

Progress in the fight against harmful fungi

4 hours ago

A group of researchers at the Max F. Perutz Laboratories has created one of the three world's largest gene libraries for the Candida glabrata yeast, which is harmful to humans. Molecular analysis of the Candida ...

How steroid hormones enable plants to grow

Aug 19, 2014

Plants can adapt extremely quickly to changes in their environment. Hormones, chemical messengers that are activated in direct response to light and temperature stimuli help them achieve this. Plant steroid ...

Surviving the attack of killer microbes

Aug 19, 2014

The ability to find food and avoid predation dictates whether most organisms live to spread their genes to the next generation or die trying. But for some species of microbe, a unique virus changes the rules ...

Histones and the mystery of cell proliferation

Aug 19, 2014

Before cells divide, they create so much genetic material that it must be wound onto spools before the two new cells can split apart. These spools are actually proteins called histones, and they must multiply ...

User comments : 0