Even bacteria use social networks

Jul 19, 2013 by Dan Krotz
Even bacteria use social networks
This model shows the role of vesicles, vesicle chains, and membrane tubes in M. xanthus biofilms. The scientists believe these connections help cells exchange signals and material. Credit: Auer lab

The next time your Facebook stream is filled with cat videos, think about Myxococcus xanthus. The single-cell soil bacterium also uses a social network. But forget silly distractions. M. xanthus relies on its connections to avoid getting eaten and to score its next meal.

That's the latest insight from a team of Berkeley Lab scientists. Using several imaging techniques, they saw for the first time that M. xanthus are connected by a network of chain-like membranes.

The scientists believe M. xanthus uses its network to quietly transfer proteins and other from one to another. This could enable the bacteria to coordinate social activities—such as evading bacterial enemies and snaring prey—without revealing its location.

"The network could be a mode of stealth communication," says Manfred Auer of Berkeley Lab's Life Sciences Division. "M. xanthus faces stiff competition and has a lot of enemies, so it pays to keep a low profile."

Although the research focused on M. xanthus, it could shed light on how other bacteria work together to pull off important processes, such as breaking down for biofuel production or cleaning up underground toxins. It could also lead to that stop by knocking out their communication systems.

This video is not supported by your browser at this time.

The work is published online in the journal Environmental Microbiology.

M. xanthus is already well known for its ability to self organize. Its highly coordinated behaviors include moving as a group and encircling its favorite foods, such as E. coli. This is a big part of what makes the bacteria so successful and ubiquitous. Pick up a handful of soil, and chances are you're holding M. xanthus.

Scientists have long known that when M. xanthus cells glom together in a stable biofilm, the area surrounding the cells is packed with spherical called vesicles. Scientists believed M. xanthus secretes these vesicles to communicate with one another. They thought the vesicles drift like messages in a bottle until other M. xanthus cells chance upon them.

But Auer and colleagues found that the vesicles form a much more targeted way of keeping in touch. They used a range of imaging techniques, including 3-D focused ion beam scanning electron microscopy, to study M. xanthus in a biofilm.

They saw that the bacteria send out chains of vesicles, like pearls strung together on a necklace. Some M. xanthus cells send out tubes made of vesicles. The chains and tubes connect every cell to several other cells. It's a microscopic intranet.

Even bacteria use social networks
Slice-through cryo-electron tomographic reconstruction of isolated vesicle chains reveals that each vesicle chain is made up of vesicles of a similar size. The scientists found that vesicle size can vary between different vesicle chains, suggesting a tight control of vesicle chain formation. Credit: Auer lab

"If M. xanthus simply shed chemical signals, then other bacteria would be able to detect it. But this network allows M. xanthus cells to only communicate with other M. xanthus cells," says Auer.

These vesicle chains and tubes had never been seen before. In addition, previously observed connections between bacterial cells had been dismissed as artifacts of sample preparation. But the Berkeley Lab approach is almost artifact free because the samples are flash frozen before they're imaged. And the cell-to-cell connections were seen via several imaging techniques such as cryo electron microscopy and cryo tomography.

There were more surprises. The scientists found that vesicle chains contain two proteins that are known to be transferrable from cell to cell when cells are touching. They think these proteins travel through the chains as cargo carriers. They also discovered that vesicle chain fractions have the ability to kill E. coli.

Next, the scientists want to study how the vesicle chains' composition changes when M. xanthus interacts with foe versus food.

Explore further: Researchers successfully clone adult human stem cells

More information: onlinelibrary.wiley.com/doi/10.1111/1462-2920.12187/abstract

Related Stories

Predatory bacterial swarm uses rippling motion to reach prey

Oct 29, 2008

Like something from a horror movie, the swarm of bacteria ripples purposefully toward their prey, devours it and moves on. Researchers at the University of Iowa are studying this behavior in Myxococcus xanthus (M. xanthus), a bact ...

An sRNA controls a bacterium's social life

May 20, 2010

For the first time, biologists have directly shown how spontaneous mutation of a small RNA (sRNA) regulatory molecule can provide an evolutionary advantage. Reporting in this week's Science, Indiana University Bloomington scient ...

For this microbe, cousins not particularly welcome

Jan 06, 2010

(PhysOrg.com) -- A bacterial species that depends on cooperation to survive is discriminating when it comes to the company it keeps. Scientists from Indiana University Bloomington and Netherlands' Centre for ...

Recommended for you

Researchers successfully clone adult human stem cells

Apr 18, 2014

(Phys.org) —An international team of researchers, led by Robert Lanza, of Advanced Cell Technology, has announced that they have performed the first successful cloning of adult human skin cells into stem ...

Researchers develop new model of cellular movement

Apr 18, 2014

(Phys.org) —Cell movement plays an important role in a host of biological functions from embryonic development to repairing wounded tissue. It also enables cancer cells to break free from their sites of ...

For resetting circadian rhythms, neural cooperation is key

Apr 17, 2014

Fruit flies are pretty predictable when it comes to scheduling their days, with peaks of activity at dawn and dusk and rest times in between. Now, researchers reporting in the Cell Press journal Cell Reports on April 17th h ...

User comments : 0

More news stories

Researchers successfully clone adult human stem cells

(Phys.org) —An international team of researchers, led by Robert Lanza, of Advanced Cell Technology, has announced that they have performed the first successful cloning of adult human skin cells into stem ...

NASA's space station Robonaut finally getting legs

Robonaut, the first out-of-this-world humanoid, is finally getting its space legs. For three years, Robonaut has had to manage from the waist up. This new pair of legs means the experimental robot—now stuck ...

Ex-Apple chief plans mobile phone for India

Former Apple chief executive John Sculley, whose marketing skills helped bring the personal computer to desktops worldwide, says he plans to launch a mobile phone in India to exploit its still largely untapped ...

Filipino tests negative for Middle East virus

A Filipino nurse who tested positive for the Middle East virus has been found free of infection in a subsequent examination after he returned home, Philippine health officials said Saturday.

Egypt archaeologists find ancient writer's tomb

Egypt's minister of antiquities says a team of Spanish archaeologists has discovered two tombs in the southern part of the country, one of them belonging to a writer and containing a trove of artifacts including reed pens ...