Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Deaths in the family cause bacteria to flee

30.06.2010
The deaths of nearby relatives has a curious effect on the bacterium Caulobacter crescentus -- surviving cells lose their stickiness.

Indiana University Bloomington biologists report in an upcoming issue of Molecular Microbiology that exposure to the extracellular DNA (eDNA) released by dying neighbors stops the sticky holdfasts of living Caulobacter from adhering to surfaces, preventing cells from joining bacterial biofilms. Less sticky cells are more likely to escape established colonies, out to where conditions may be better.

Harmless Caulobacter live in nutrient-poor, aqueous environments like lakes, rivers, and even tap water. Like many other bacteria, Caulobacter form biofilms, aggregations of cells held in place by a sticky matrix produced by the bacteria themselves. Bacteria in biofilms are more resistant to predators and to antibiotics, and are less affected by environmental stress. However, if environmental conditions worsen, it becomes advantageous for the bacteria to get away.

That presents a special problem for Caulobacter. In 2006, microbiologist Yves Brun, the project's principal investigator, and Brown University colleagues learned that the sugar-protein glue the bacteria use to attach themselves to the biofilm matrix is the strongest adhesive known in nature. Once a cell joins the collective, it is stuck there.

Caulobacter solves the problem of getting stuck in poor conditions by producing a clone of itself through cell replication. The mother cell heroically stays behind. But the daughter cell, called the "swarmer," starts out life with a flagellum, allowing it to move through water. The daughter has the option of swimming away from its mother and its relatives in the biofilm, or of settling in the same biofilm where it was born.

"It appears that a product of cell death can help these swarmer cells sense their environment and determine if this is a good place to settle," said IU Bloomington postdoctoral fellow Cécile Berne, the paper's lead author.

As is often the case in science, the discovery was a result of serendipity.

"We initially noticed that by mixing two crowded cultures of the bacterium, we would get less biofilm formation," Berne said. "This got us thinking about the fact that throughout the living world, high population density stimulates dispersal. We set out to test whether bacteria were producing something that allowed them to switch between these two very different states of bacterial life, staying put in a biofilm or dispersing to colonize new surfaces. We found that eDNA released by dead cells as they lyse, or blow up, was binding directly to the holdfast of the newborn swarmer cells and making it less sticky. It's kind of like having a sticky substance on your fingertip and covering it with dust -- once the holdfast is coated with eDNA, it can't stick to a new surface, so the cell will be more likely to swim away."

The researchers don't know for certain whether the escape behavior of swarmer cells is a result of happenstance -- a happy accident that the holdfasts and eDNA interact -- or whether the interaction represents an active process that has been modified and fine-tuned through natural selection. Irrespective, more cells will die in worse environments, producing more eDNA, and stimulating more dispersal of the swarmer cells.

"Responding to relatives' eDNA makes a lot of sense for a bacterium because the DNA will be almost identical," Brun said. "What may be good for one bacterial species may be bad for another and vice versa. So you would not want to respond to DNA from another species, which has a different sequence than your and your siblings' DNA. What better way to sense whether the environment is bad for your species or your type than to be sensitive to the deaths of your close relatives? Generally, biofilms are good for bacteria. But when your siblings are starting to die around you, you know it's time to find a better place to live."

But a major mystery remains, says postdoctoral fellow David Kysela, a co-author of the paper.

"How does Caulobacter discriminate between its siblings' DNA and other DNA in the environment?" Kysela asked. "Clearly there's something special about Caulobacter DNA, since swimming cells ignore DNA from unrelated species. Everything we've seen so far indicates that something about the particular sequence of Caulobacter DNA is responsible, but we're still digging. A lot of bacterial species use a similar holdfast to stick to surfaces and form biofilms. It will be interesting to see if these species also respond to their own DNA."

Ongoing funding to Yves Brun from the National Institutes of Health helped support the project.

To speak with Berne, Brun, or Kysela, please contact David Bricker, University Communications, at 812-856-9035 or brickerd@indiana.edu.

"A bacterial extracellular DNA inhibits settling of motile progeny cells within a biofilm," by Cécile Berne, David T. Kysela, and Yves V. Brun, Molecular Microbiology (online; iss. TBD)

David Bricker | EurekAlert!
Further information:
http://www.indiana.edu

Further reports about: Caulobacter DNA Molecular Target bacterial species microbiology

More articles from Life Sciences:

nachricht Symbiotic bacteria: from hitchhiker to beetle bodyguard
28.04.2017 | Johannes Gutenberg-Universität Mainz

nachricht Nose2Brain – Better Therapy for Multiple Sclerosis
28.04.2017 | Fraunhofer-Institut für Grenzflächen- und Bioverfahrenstechnik IGB

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Fighting drug resistant tuberculosis – InfectoGnostics meets MYCO-NET² partners in Peru

28.04.2017 | Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

 
Latest News

Wireless power can drive tiny electronic devices in the GI tract

28.04.2017 | Medical Engineering

Ice cave in Transylvania yields window into region's past

28.04.2017 | Earth Sciences

Nose2Brain – Better Therapy for Multiple Sclerosis

28.04.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>