Competition between two sibling colonies of the Paenibacillus > dendritiformis bacteria grown side by side. The cells on the inner edges of the two colonies are dead. As bacteria become increasingly resistant to antibiotics, creating indestructible superbugs, bacterial infection has …
Prof. Eshel Ben-Jacob, a scientist at Tel Aviv University, discovered that if he exposed a colony of bacteria to the same chemical signals that the bacteria produce to fight off competition, they would end up killing each other.
“Our studies suggest this is a new way to fight off bacteria,” says Ben-Jacob, an award-winning scientist from TAU’s School of Physics and Astronomy. “This strategy seems very promising — it’s highly unlikely that the bacteria will develop resistance to a compound that they themselves produce.”
Cannibalism in bacteria caused by stress
Cannibalism among bacteria, says Ben-Jacob, is a strange cooperative behavior elicited under stress. In response to stressors such as starvation, heat shock and harmful chemicals, the bacteria reduce their population with a chemical that kills sister cells in the colony.
“It works in much the same way that organisms reduce production of some of their cells when under starvation,” says Ben-Jacob. “But what’s most interesting among bacteria is that they appear to develop a rudimentary form of social intelligence, reflected in a sophisticated and delicate chemical dialogue conducted to guarantee that only a fraction of the cells are killed.”
Ben-Jacob’s research, published this month in the journal Proceedings of the National Academy of Science, was carried out in collaboration with a group of scientists from Texas University, led by Prof. Harry Swinney and his post-doctoral fellow Dr. Avraham Be’er, formerly of Tel Aviv University.
The problem of bacteria becoming resistant to antibiotics is of growing concern worldwide. In 2005, in the United States alone, nearly 19,000 people died after being infected with virulent drug-resistant bacteria in hospitals and nursing homes, according to a government study published in The Journal of the American Medical Association. It’s a figure that exceeds those attributed to HIV-AIDS, Parkinson’s disease, or emphysema annually.
New drugs may take years and a small fortune to develop, but even when these are introduced, it only takes a year for bacteria to develop a resistance to it.
In the TAU-Texas University research, scientists investigated what happens when two sibling colonies of bacteria – Paenibacillus dendritiformis , (a special strain of social bacteria discovered by Ben-Jacob) – are grown side by side on a hard surface with limited nutrients. Surprisingly, the two colonies not only inhibited each other from growing into the territory between them but induced the death of those cells close to the border, researchers found.
Bacteria have more intelligence than we think
Even more interesting to the scientists was the discovery that cell death stopped when they blocked the exchange of chemical messages between the two colonies. “It looks as if a message from one colony initiates population reduction in the cells across the gap. Each colony simultaneously turns away from the course that will bring both into confrontation,” says Ben-Jacob, who is also working to find treatments for neurological disorders such as epilepsy, Alzheimer’s and Parkinson’s disease using nano-technology.
Bacteria, Ben-Jacob says, know how to glean information from the environment, talk with each other, distribute tasks and generate collective memory. He believes that bacterial social intelligence, conveyed through advanced chemical language, allows bacteria to turn their colonies into massive “brains” that process information, learning from past experience to solve unfamiliar problems and better cope with new challenges.
It’s a discovery that he believes offers new hope for fighting both the bacterial infections of today and the super-super-bugs of the future.
“If we want to survive the challenges posed by bacteria, we must first recognize that bacteria are not the simple, solitary creatures of limited capabilities they were long believed to be,” concludes Ben-Jacob, who is now investigating practical applications for his current research findings.