HU discovers how bacteria 'chat'

Evidence indicates that bacteria seldom behave as isolated organisms.

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October 25, 2007 22:53
1 minute read.
HU discovers how bacteria 'chat'

bacteria 224.88. (photo credit: Hebrew University of J'lem)

The discovery by Hebrew University-Hadassah Medical School researchers of a communication factor that makes it possible for bacteria to "talk to each other" and causes their death could lead to development of a new class of antibiotics. In an article to be published Friday in the prestigious journal Science, the Jerusalem scientists describe the communication factor that is produced by the intestinal bacteria Escherichia coli. The factor, secreted by the bacteria, serves as a communication signal between single bacterial cells. Bacteria are traditionally considered unicellular organisms, but increasing experimental evidence indicates that bacteria seldom behave as isolated organisms. Instead, they are members of a community in which the isolated organisms communicate among themselves, thereby manifesting some multicellular behavior. The research was carried out by a group headed by Prof. Hanna Engelberg-Kulka of the medical school's department of molecular biology. It includes PhD student Ilana Kolodkin-Gal, Dr. Ronen Hazan and Dr. Ariel Gaathon. The communication factor, called extracellular death factor (EDF), enables the activation of a built-in "suicide module" that is located on the bacterial chromosome and is responsible for bacterial cell death under stressful conditions. While suicidal cell death is counterproductive for the individual bacterial cell, it becomes effective for the bacterial community as a whole by the simultaneous action of a group of cells that are signaled by EDF. Under stressful conditions in which the EDF is activated, a major subpopulation within the bacterial culture dies, allowing the survival of the population as a whole. Understanding how the EDF functions may provide a lead for a new and more efficient class of antibiotics that specifically trigger bacterial cell death in the intestine bacteria E. coli and probably in many other bacteria, including those pathogens that also carry the "suicide module." Given the growing resistance of bacteria to existing antibiotics, this would be a blessing. The discovered communication factor is a novel biological molecule, Engelberg-Kulka said. It is a small-protein chain (peptide) produced by the bacteria. The chemical characterization of the new communication factor was particularly difficult for the researchers because it is present in the bacterial culture in minute amounts, and the factor decomposes under the conditions that are routinely used during standard chemical characterization methods.


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