Social bacteria

http://www.nsf.gov/discoveries/disc_summ.jsp?cntn_id=129976

"Social" bacteria that work together to hunt for food and survive under harsh conditions

December 20, 2013

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some bacteria are quite social, chief among them Myxococcus xanthus, a soil-dwelling bacterium that organizes itself into multi-cellular, three-dimensional structures made up of thousands of cells that work together to hunt for food and survive under harsh conditions.

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Myxococcus xanthus is "predatory," meaning it eats other microbes, although it is not harmful to humans. It is of great interest to researchers because of its self-made complex spatial formations, some even visible to the naked eye, and because it can kill efficiently and digest a wide range of microbial species.

"Their three-dimensional structures contain hundreds of thousands of bacteria, plus extra cellular material that holds the bacteria together like glue," says the National Science Foundation (NSF)-funded computational biologist,

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"The most primitive form of life is single-cell life," Igoshin says. "The next step up would be going from single cells to multicellular organisms. These bacteria are somewhat in the middle."

When food is plentiful, these bacteria move in coordinated swarms, called ripples, often containing thousands of cells, which secrete enzymes into the environment to kill their prey and digest it outside their structure before taking in the resulting nutrients.

"M. xanthus has the ability to produce some powerful antibiotics that kill other species and enzymes that chew up the prey proteins into small segments," Igoshin says. "Single cells can't produce enough of these antibiotics or enzymes to effectively kill their prey, which is why they hunt together as a group."

But when food is scarce, M. xanthus takes another shape, forming itself into mounds of spores called fruiting bodies, where they can survive for a long time, sometimes for many years, until conditions improve and they can germinate again. "A single spore wouldn't survive," he says. "They need to be together."

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http://www.wired.co.uk/magazine/archive/2013/11/start/bacteria

Nov. 8, 2013
by Madhumita Venkataramanan

These 600 billion soil bacteria, known as Paenibacillus vortex are one of the most elaborately structured bacterial communities in nature. "These bacteria have a great social life, they work like a team, using chemicals to communicate in a very sophisticated way," says biophysicist Eshel Ben-Jacob, who captured these images in his lab at Tel Aviv University.

Recently, he found these swarms have a social intelligence similar to that of humans. The bacteria use algae as a 'tool' to produce food; they transport algae towards light-rich places, where the algae produce biofuel. They also move fungal spores to locations where the spores can germinate and put out roots. "The bacteria use these roots to cross into places they could otherwise never get to," says Ben-Jacob.

His team also found that the microbes can adapt to environmental dangers (such as antibiotics), distribute tasks, make collective decisions about risk and hoard food. "Compared to disease-causing bacteria, who live comfortably in humans, these bacteria have to survive in much more complex ecosystems," Ben-Jacob says. "Just think how much smarter that makes them."